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Re: [ekg_club] postextrasystolic pause

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  • Klaus Skrudland
    Niklah - I m not sure what you mean when you refer to unreliable P wave detection...? The problem here was just that the bigeminy concealed the base
    Message 1 of 17 , Feb 1, 2009
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      Niklah - 
      I'm not sure what you mean when you refer to unreliable P wave detection...? The problem here was just that the bigeminy concealed the base rate/normal interval. I agree, you can't claim a pause to be compensatory nor noncompensatory unless you know the normal intervals. That is established also through the formula that Paul mentioned. 

      And when it comes to paper speed.. I'm sorry if I confuse you. I'd wish the opposite..! I live in Norway, and here there standard 12 lead paper speed is 50 mm/s. I do not know why. Or to put it another way, I can't undetstand why you guys would want to use 25mm/s. When running 50mm/s, it is much easier to spot P waves, to measure intervals and to look for those tiny little things that often tip the diagnosis in the right direction.. 

      :-)

      klaus

      On Sun, Feb 1, 2009 at 4:59 AM, Nikiah Nudell <medicnick@...> wrote:

      Klaus - I have seen this same pattern a number of times as well in EGMs where you do not have reliable Pwave detection. Its tricky... and we've written about them before.
       
      I don't think you can claim it to be "compensatory" unless you actually know the basal intervals.
       
      Also, I think you are messing with our minds with 50mm/s strips. Is there any particular reason why you use this speed?
       
      Thanks,
      Nick

      On Sat, Jan 31, 2009 at 18:00, Klaus Skrudland <lapsklaus@...> wrote:

      Paul - 


      It's a pleasure discussing these matters with someone with as much insight on the issue as you. You're perfectly right, the problem is that there is no normal interval or no base rate. And you're correct, this is exactly what I have been banging my head against the wall over. 

      For now, I've run out of clues on this one.. and as you say, the formula unfortunately cannon be used towards solving for X..  There might be other mathematical relationships between the coupling interval and the pause that could reveal eventual atrial reset, but that is unknown to me.. 

      Anyway, such discussions as this is very fun anyhow.. My brain got kick started too, thanks for participating..! I'll let you (and the rest of the world) know if I come across anything on this..

      The ECG that this problem is derived from is by the way presented in my blog right here: 

       As you can see, I am trying to establish the ectopic origin of the premature contractions, using different approaches. And when I wanted to look at the postextrasystolic pause and apply the formula mentioned... I couldn't..! :-)

      Thanks! Klaus

      On Sat, Jan 31, 2009 at 11:24 PM, <PMATERAMD@...> wrote:

      hi again klaus,
      basically you want to know if we can determine on an ecg wether or not an ecg showing atrial bigeminy reveals a compensatory pause(ie atrial reset) or non-compensatory pause(ie no atrial reset),
      hmmmm ,  .., that's a good one,
       
      because there is no "normal" interval or known nsr rate, ... that complicates the issue, i would think that on surface ecgs there is not enough "data", ie, we dont have the base rate (so we cant interpolate the N_int) and/or base normal interval (N_int) , ..., as you know mathematically we usually would only need 2 of the 3 components of the formula to calculate the third but we are not solving for X, we are performing a relational equation to determine if the left side is = to right or if left side is > than right, ... i will need to roll this one around for a while more, let me know if you come across a viable answer / theory,
      great question, gets the old neurons kick started, thanks,
      Paul
      Paul Matera, MD, FAEP, FAAIM, EMTP
      Clinical Medicine, Emergency Services, Clinical Electrocardiography, Medical Education
      Director Emeritus - Critical Care Units/Emergency Medicine, Providence Hospital, DC
      Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR Team
      Clinical Associate Professor - Medicine and Health Care Science, GWU, DC
       
      In a message dated 1/31/2009 1:36:05 P.M. Eastern Standard Time, lapsklaus@... writes:

      Thanks a lot, Paul. I appreciate your help, but I'm already familiar with that formula. I've written about it and demonstrated it often in my blog (ecgblog.wordpress.com). I'm glad you mention it though, because I've been trying to apply this formula on an EKG that I have, and I can't figure out which interval to use as N_int. The strip shows an atrial bigeminal rhythm, and actually only shows coupling intervals and postextrasystolic pauses. 



      Any ideas?



      With PACs the pause is normally noncompensatory. 

      On Sat, Jan 31, 2009 at 6:50 PM, <PMATERAMD@...> wrote:

      if you just want a simple format to calculate odds of compensatory v non-compensatory you can use the formulas below that help give you the answer, my prior comments were directed so we can all think through what is happening and why

      C_int + P_ex > 2 x N_int = Non-compensatory, pause is longer than the normal interval however not long enough for the coupling interval and the compensatory pause to be 2X the length of the normal interval 

      C_int + P_ex = 2 x N_int = Compensatory, pause is long and the distance between the two normal beats is twice as long the normal interval in the underlying rhythm
       
      where:
       
      Coupling interval = C_int = The interval PP or RR between a normal sinus beat and premature beat
       
      Postextrasystole pause = P_ex = The following pause after a premature beat
       
      Normal interval = N_int = The interval , PP or RR
       
      hope this helps some
       
      Paul
       
       
      Paul Matera, MD

       

       
      In a message dated 1/31/2009 11:20:25 A.M. Eastern Standard Time, lapsklaus@... writes:

      Paul - 

      I do know the Ashman Phenomenon and the underlying mechamisms you describe, but this doesn't help me answer my initial question. Ashman beats usually occur during afib, due to changes in refractory times, and the aberrantly conducted complexes are usually seen after a long-short cycle. The criteria for Ashman Phenomenon were well described by Charles Fisch, and are called the Fisch Criteria if I remember correctly.

      Anyhow, my question was how one can differentiate between compensatory and noncompensatory extrasystolic pauses in a bigeminal pattern during sinus rhythm, since there is no "normal" PP interval to measure by. 

      I agree that it is essential to understand cellular physiology, etc. I like to think that I understand these things very well, but still I can't quite figure out the above. You seem to be skilled at this field, can you help me with an answer? :-)


      On Sat, Jan 31, 2009 at 4:29 PM, <PMATERAMD@...> wrote:

      now we can muddy the waters a little more, ashman's phenomenon is similar to what you are discussing ....knowing how and why this occurs, especially since this phenom occurs after a "normal" beat has already occurred, all this goes back to one of my recent prior posts, i urge all colleagues here that do not fully understand cellular physiology, ie, resting potential, refractory period, excitability, automaticity, all based on sodium in, potassium out, electron charging, all controlled by calcium channels/02/pH, ..., as i said if you understand these issue, understanding the outcome, ie the ecg, is easier,
      stay safe,
      Paul
      Paul Matera, MD, FAEP, FAAIM, EMTP
      Clinical Medicine, Emergency Services, Clinical Electrocardiography, Medical Education
      Director Emeritus - Critical Care Units/Emergency Medicine, Providence Hospital, DC
      Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR Team
      Clinical Associate Professor - Medicine and Health Care Science, GWU, DC
       
      In a message dated 1/30/2009 8:45:34 P.M. Eastern Standard Time, lapsklaus@... writes:

      Niklah -

      I have understood that:
      A compensatory postextrasystolic pause occurs when a premature impulse spreads without depolarizing the atria, and thereby without resetting the SA Node. With a PVC, the early depolarization is normally isolated within the ventricular conduction tissue and therefore the SA Node is oblivious to the occured event and will continue pacing in a timely fashion. By definition, AV dissociation is present at the time the PVC occurs, and therefore the next sinus beat will appear precicely on time. On a surface EKG the coupling interval + the pause will be twice the length of the normal sinus interval.

      Although, a PVC can produce a non-compensatory pause by resetting the SA node via retrograde (VA) conduction to the atria. In comparison, a PAC will normally activate the whole atria including the SA Node, and sinoatrial pacing will therefore be reset. Until the SA Node generates a new impulse, there will be a pause. This pause is not a multiple of the normal interval, and is called non-compensatory when seen on a surface EKG.

      klaus


      On Sat, Jan 31, 2009 at 2:31 AM, Nikiah Nudell <medicnick@...> wrote:

      Klaus what is your physiologic definition of a compensatory pause?

       

      From: ekg_club@yahoogroups.com [mailto:ekg_club@yahoogroups.com] On Behalf Of Klaus Skrudland
      Sent: Friday, January 30, 2009 19:29
      To: ekg_club@yahoogroups.com
      Subject: [ekg_club] postextrasystolic pause

       

      Just an academic question here about the postextrasystolic pause with premature beats. I'm hoping someone can help.

      I've got a strip showing atrial bigeminy, and although PACs usually reset the SA Node and therefore present with noncompensatory pauses, I'd like to prove this. In atrial bigeminy, there is no normal sinus interval, as each sinus beat is followed by a PAC.

      My question is therefore: Can the postextrasystolic pause be determined in a bigeminal rhythm?


      To explain this a bit more thorough:

      To establish whether a postextrasystolic pause is compensatory or noncompensatory, one needs to look at the length of the normal interval and compare it to the added length of the coupling interval and the postextrasystolic pause.

      Compensatory pause: Coupling interval length + postex. pause length = 2 x normal interval (sinus cycle length)
      Noncompensatory pause: Coupling interval length + postex. pause length < 2 x normal interval (sinus cycle length)

      In a bigeminal rhythm, there is no normal interval, so how can I determine whether the pauses are compensatory or not?

      Anyone who can help?


      - klaus




       


      From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.




      --
      Mvh,
      Klaus Nilsen Skrudland

      http://www.sykepleieforum.no
      http://www.lapsklaus.com
      http://ecgblog.wordpress.com
      + 47 99 38 67 55



      From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.




      --
      Mvh,
      Klaus Nilsen Skrudland

      http://www.sykepleieforum.no
      http://www.lapsklaus.com
      http://ecgblog.wordpress.com
      + 47 99 38 67 55

       
       



      From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.



      --
      Mvh,
      Klaus Nilsen Skrudland

      http://www.sykepleieforum.no
      http://www.lapsklaus.com
      http://ecgblog.wordpress.com
      + 47 99 38 67 55





      --
      Mvh,
      Klaus Nilsen Skrudland

      http://www.sykepleieforum.no
      http://www.lapsklaus.com
      http://ecgblog.wordpress.com
      + 47 99 38 67 55
    • PMATERAMD@aol.com
      on this issue of paper speed and subsequently mV amplitude, as you know the US std is 25mm/sec and 10mm/mV, I often ask for 12 leads and 3 lead rhythm
      Message 2 of 17 , Feb 1, 2009
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        on this issue of paper speed and subsequently mV amplitude, as you know the US std is 25mm/sec  and 10mm/mV,   I often ask for 12 leads and 3 lead rhythm strips the be run at 50mm/sec and 20mm/mV  which helps magnify and bring out subtle "p", allows more accurate intervals, etc, just be sure the ecg is clearly marked as 50mm , or you will get a call from the next consultant asking why your pt with a heart rate of 30 isnt being treated ,
         
        paul
         
        In a message dated 2/1/2009 8:02:39 A.M. Eastern Standard Time, lapsklaus@... writes:

        Niklah - 

        I'm not sure what you mean when you refer to unreliable P wave detection... ? The problem here was just that the bigeminy concealed the base rate/normal interval. I agree, you can't claim a pause to be compensatory nor noncompensatory unless you know the normal intervals. That is established also through the formula that Paul mentioned. 

        And when it comes to paper speed.. I'm sorry if I confuse you. I'd wish the opposite..! I live in Norway, and here there standard 12 lead paper speed is 50 mm/s. I do not know why. Or to put it another way, I can't undetstand why you guys would want to use 25mm/s. When running 50mm/s, it is much easier to spot P waves, to measure intervals and to look for those tiny little things that often tip the diagnosis in the right direction.. 

        :-)

        klaus

        On Sun, Feb 1, 2009 at 4:59 AM, Nikiah Nudell <medicnick@gmail. com> wrote:

        Klaus - I have seen this same pattern a number of times as well in EGMs where you do not have reliable Pwave detection. Its tricky... and we've written about them before.
         
        I don't think you can claim it to be "compensatory" unless you actually know the basal intervals.
         
        Also, I think you are messing with our minds with 50mm/s strips. Is there any particular reason why you use this speed?
         
        Thanks,
        Nick

        On Sat, Jan 31, 2009 at 18:00, Klaus Skrudland <lapsklaus@gmail. com> wrote:

        Paul - 


        It's a pleasure discussing these matters with someone with as much insight on the issue as you. You're perfectly right, the problem is that there is no normal interval or no base rate. And you're correct, this is exactly what I have been banging my head against the wall over. 

        For now, I've run out of clues on this one.. and as you say, the formula unfortunately cannon be used towards solving for X..  There might be other mathematical relationships between the coupling interval and the pause that could reveal eventual atrial reset, but that is unknown to me.. 

        Anyway, such discussions as this is very fun anyhow.. My brain got kick started too, thanks for participating. .! I'll let you (and the rest of the world) know if I come across anything on this..

        The ECG that this problem is derived from is by the way presented in my blog right here: 

         As you can see, I am trying to establish the ectopic origin of the premature contractions, using different approaches. And when I wanted to look at the postextrasystolic pause and apply the formula mentioned... I couldn't..! :-)

        Thanks! Klaus

        On Sat, Jan 31, 2009 at 11:24 PM, <PMATERAMD@aol. com> wrote:

        hi again klaus,
        basically you want to know if we can determine on an ecg wether or not an ecg showing atrial bigeminy reveals a compensatory pause(ie atrial reset) or non-compensatory pause(ie no atrial reset),
        hmmmm ,  .., that's a good one,
         
        because there is no "normal" interval or known nsr rate, ... that complicates the issue, i would think that on surface ecgs there is not enough "data", ie, we dont have the base rate (so we cant interpolate the N_int) and/or base normal interval (N_int) , ..., as you know mathematically we usually would only need 2 of the 3 components of the formula to calculate the third but we are not solving for X, we are performing a relational equation to determine if the left side is = to right or if left side is > than right, ... i will need to roll this one around for a while more, let me know if you come across a viable answer / theory,
        great question, gets the old neurons kick started, thanks,
        Paul
        Paul Matera, MD, FAEP, FAAIM, EMTP
        Clinical Medicine, Emergency Services, Clinical Electrocardiography , Medical Education
        Director Emeritus - Critical Care Units/Emergency Medicine, Providence Hospital, DC
        Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR Team
        Clinical Associate Professor - Medicine and Health Care Science, GWU, DC
         
        In a message dated 1/31/2009 1:36:05 P.M. Eastern Standard Time, lapsklaus@gmail. com writes:

        Thanks a lot, Paul. I appreciate your help, but I'm already familiar with that formula. I've written about it and demonstrated it often in my blog (ecgblog.wordpress. com). I'm glad you mention it though, because I've been trying to apply this formula on an EKG that I have, and I can't figure out which interval to use as N_int. The strip shows an atrial bigeminal rhythm, and actually only shows coupling intervals and postextrasystolic pauses. 



        Any ideas?



        With PACs the pause is normally noncompensatory. 

        On Sat, Jan 31, 2009 at 6:50 PM, <PMATERAMD@aol. com> wrote:

        if you just want a simple format to calculate odds of compensatory v non-compensatory you can use the formulas below that help give you the answer, my prior comments were directed so we can all think through what is happening and why

        C_int + P_ex > 2 x N_int = Non-compensatory, pause is longer than the normal interval however not long enough for the coupling interval and the compensatory pause to be 2X the length of the normal interval 

        C_int + P_ex = 2 x N_int = Compensatory, pause is long and the distance between the two normal beats is twice as long the normal interval in the underlying rhythm
         
        where:
         
        Coupling interval = C_int = The interval PP or RR between a normal sinus beat and premature beat
         
        Postextrasystole pause = P_ex = The following pause after a premature beat
         
        Normal interval = N_int = The interval , PP or RR
         
        hope this helps some
         
        Paul
         
         
        Paul Matera, MD

         

         
        In a message dated 1/31/2009 11:20:25 A.M. Eastern Standard Time, lapsklaus@gmail. com writes:

        Paul - 

        I do know the Ashman Phenomenon and the underlying mechamisms you describe, but this doesn't help me answer my initial question. Ashman beats usually occur during afib, due to changes in refractory times, and the aberrantly conducted complexes are usually seen after a long-short cycle. The criteria for Ashman Phenomenon were well described by Charles Fisch, and are called the Fisch Criteria if I remember correctly.

        Anyhow, my question was how one can differentiate between compensatory and noncompensatory extrasystolic pauses in a bigeminal pattern during sinus rhythm, since there is no "normal" PP interval to measure by. 

        I agree that it is essential to understand cellular physiology, etc. I like to think that I understand these things very well, but still I can't quite figure out the above. You seem to be skilled at this field, can you help me with an answer? :-)


        On Sat, Jan 31, 2009 at 4:29 PM, <PMATERAMD@aol. com> wrote:

        now we can muddy the waters a little more, ashman's phenomenon is similar to what you are discussing ....knowing how and why this occurs, especially since this phenom occurs after a "normal" beat has already occurred, all this goes back to one of my recent prior posts, i urge all colleagues here that do not fully understand cellular physiology, ie, resting potential, refractory period, excitability, automaticity, all based on sodium in, potassium out, electron charging, all controlled by calcium channels/02/ pH, ..., as i said if you understand these issue, understanding the outcome, ie the ecg, is easier,
        stay safe,
        Paul
        Paul Matera, MD, FAEP, FAAIM, EMTP
        Clinical Medicine, Emergency Services, Clinical Electrocardiography , Medical Education
        Director Emeritus - Critical Care Units/Emergency Medicine, Providence Hospital, DC
        Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR Team
        Clinical Associate Professor - Medicine and Health Care Science, GWU, DC
         
        In a message dated 1/30/2009 8:45:34 P.M. Eastern Standard Time, lapsklaus@gmail. com writes:

        Niklah -

        I have understood that:
        A compensatory postextrasystolic pause occurs when a premature impulse spreads without depolarizing the atria, and thereby without resetting the SA Node. With a PVC, the early depolarization is normally isolated within the ventricular conduction tissue and therefore the SA Node is oblivious to the occured event and will continue pacing in a timely fashion. By definition, AV dissociation is present at the time the PVC occurs, and therefore the next sinus beat will appear precicely on time. On a surface EKG the coupling interval + the pause will be twice the length of the normal sinus interval.

        Although, a PVC can produce a non-compensatory pause by resetting the SA node via retrograde (VA) conduction to the atria. In comparison, a PAC will normally activate the whole atria including the SA Node, and sinoatrial pacing will therefore be reset. Until the SA Node generates a new impulse, there will be a pause. This pause is not a multiple of the normal interval, and is called non-compensatory when seen on a surface EKG.

        klaus


        On Sat, Jan 31, 2009 at 2:31 AM, Nikiah Nudell <medicnick@gmail. com> wrote:

        Klaus what is your physiologic definition of a compensatory pause?

         

        From: ekg_club@yahoogroup s.com [mailto:ekg_club@yahoogroup s.com] On Behalf Of Klaus Skrudland
        Sent: Friday, January 30, 2009 19:29
        To: ekg_club@yahoogroup s.com
        Subject: [ekg_club] postextrasystolic pause

         

        Just an academic question here about the postextrasystolic pause with premature beats. I'm hoping someone can help.

        I've got a strip showing atrial bigeminy, and although PACs usually reset the SA Node and therefore present with noncompensatory pauses, I'd like to prove this. In atrial bigeminy, there is no normal sinus interval, as each sinus beat is followed by a PAC.

        My question is therefore: Can the postextrasystolic pause be determined in a bigeminal rhythm?


        To explain this a bit more thorough:

        To establish whether a postextrasystolic pause is compensatory or noncompensatory, one needs to look at the length of the normal interval and compare it to the added length of the coupling interval and the postextrasystolic pause.

        Compensatory pause: Coupling interval length + postex. pause length = 2 x normal interval (sinus cycle length)
        Noncompensatory pause: Coupling interval length + postex. pause length < 2 x normal interval (sinus cycle length)

        In a bigeminal rhythm, there is no normal interval, so how can I determine whether the pauses are compensatory or not?

        Anyone who can help?


        - klaus




         


        From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.




        --
        Mvh,
        Klaus Nilsen Skrudland

        http://www.sykeplei eforum.no
        http://www.lapsklau s.com
        http://ecgblog. wordpress. com
        + 47 99 38 67 55



        From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.




        --
        Mvh,
        Klaus Nilsen Skrudland

        http://www.sykeplei eforum.no
        http://www.lapsklau s.com
        http://ecgblog. wordpress. com
        + 47 99 38 67 55

         
         



        From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.



        --
        Mvh,
        Klaus Nilsen Skrudland

        http://www.sykeplei eforum.no
        http://www.lapsklau s.com
        http://ecgblog. wordpress. com
        + 47 99 38 67 55





        --
        Mvh,
        Klaus Nilsen Skrudland

        http://www.sykeplei eforum.no
        http://www.lapsklau s.com
        http://ecgblog. wordpress. com
        + 47 99 38 67 55



        From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.
      • Klaus Skrudland
        Exactly... so 50 mm/s should be the international standard! ;-)Go Norway! :) ... -- Mvh, Klaus Nilsen Skrudland http://www.sykepleieforum.no
        Message 3 of 17 , Feb 1, 2009
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          Exactly... so 50 mm/s should be the international standard! ;-)
          Go Norway! :)

          On Sun, Feb 1, 2009 at 2:15 PM, <PMATERAMD@...> wrote:

          on this issue of paper speed and subsequently mV amplitude, as you know the US std is 25mm/sec  and 10mm/mV,   I often ask for 12 leads and 3 lead rhythm strips the be run at 50mm/sec and 20mm/mV  which helps magnify and bring out subtle "p", allows more accurate intervals, etc, just be sure the ecg is clearly marked as 50mm , or you will get a call from the next consultant asking why your pt with a heart rate of 30 isnt being treated ,
           
          paul
           
          In a message dated 2/1/2009 8:02:39 A.M. Eastern Standard Time, lapsklaus@... writes:

          Niklah - 

          I'm not sure what you mean when you refer to unreliable P wave detection...? The problem here was just that the bigeminy concealed the base rate/normal interval. I agree, you can't claim a pause to be compensatory nor noncompensatory unless you know the normal intervals. That is established also through the formula that Paul mentioned. 

          And when it comes to paper speed.. I'm sorry if I confuse you. I'd wish the opposite..! I live in Norway, and here there standard 12 lead paper speed is 50 mm/s. I do not know why. Or to put it another way, I can't undetstand why you guys would want to use 25mm/s. When running 50mm/s, it is much easier to spot P waves, to measure intervals and to look for those tiny little things that often tip the diagnosis in the right direction.. 

          :-)

          klaus

          On Sun, Feb 1, 2009 at 4:59 AM, Nikiah Nudell <medicnick@...> wrote:

          Klaus - I have seen this same pattern a number of times as well in EGMs where you do not have reliable Pwave detection. Its tricky... and we've written about them before.
           
          I don't think you can claim it to be "compensatory" unless you actually know the basal intervals.
           
          Also, I think you are messing with our minds with 50mm/s strips. Is there any particular reason why you use this speed?
           
          Thanks,
          Nick

          On Sat, Jan 31, 2009 at 18:00, Klaus Skrudland <lapsklaus@...> wrote:

          Paul - 


          It's a pleasure discussing these matters with someone with as much insight on the issue as you. You're perfectly right, the problem is that there is no normal interval or no base rate. And you're correct, this is exactly what I have been banging my head against the wall over. 

          For now, I've run out of clues on this one.. and as you say, the formula unfortunately cannon be used towards solving for X..  There might be other mathematical relationships between the coupling interval and the pause that could reveal eventual atrial reset, but that is unknown to me.. 

          Anyway, such discussions as this is very fun anyhow.. My brain got kick started too, thanks for participating..! I'll let you (and the rest of the world) know if I come across anything on this..

          The ECG that this problem is derived from is by the way presented in my blog right here: 

           As you can see, I am trying to establish the ectopic origin of the premature contractions, using different approaches. And when I wanted to look at the postextrasystolic pause and apply the formula mentioned... I couldn't..! :-)

          Thanks! Klaus

          On Sat, Jan 31, 2009 at 11:24 PM, <PMATERAMD@...> wrote:

          hi again klaus,
          basically you want to know if we can determine on an ecg wether or not an ecg showing atrial bigeminy reveals a compensatory pause(ie atrial reset) or non-compensatory pause(ie no atrial reset),
          hmmmm ,  .., that's a good one,
           
          because there is no "normal" interval or known nsr rate, ... that complicates the issue, i would think that on surface ecgs there is not enough "data", ie, we dont have the base rate (so we cant interpolate the N_int) and/or base normal interval (N_int) , ..., as you know mathematically we usually would only need 2 of the 3 components of the formula to calculate the third but we are not solving for X, we are performing a relational equation to determine if the left side is = to right or if left side is > than right, ... i will need to roll this one around for a while more, let me know if you come across a viable answer / theory,
          great question, gets the old neurons kick started, thanks,
          Paul
          Paul Matera, MD, FAEP, FAAIM, EMTP
          Clinical Medicine, Emergency Services, Clinical Electrocardiography, Medical Education
          Director Emeritus - Critical Care Units/Emergency Medicine, Providence Hospital, DC
          Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR Team
          Clinical Associate Professor - Medicine and Health Care Science, GWU, DC
           
          In a message dated 1/31/2009 1:36:05 P.M. Eastern Standard Time, lapsklaus@... writes:

          Thanks a lot, Paul. I appreciate your help, but I'm already familiar with that formula. I've written about it and demonstrated it often in my blog (ecgblog.wordpress.com). I'm glad you mention it though, because I've been trying to apply this formula on an EKG that I have, and I can't figure out which interval to use as N_int. The strip shows an atrial bigeminal rhythm, and actually only shows coupling intervals and postextrasystolic pauses. 



          Any ideas?



          With PACs the pause is normally noncompensatory. 

          On Sat, Jan 31, 2009 at 6:50 PM, <PMATERAMD@...> wrote:

          if you just want a simple format to calculate odds of compensatory v non-compensatory you can use the formulas below that help give you the answer, my prior comments were directed so we can all think through what is happening and why

          C_int + P_ex > 2 x N_int = Non-compensatory, pause is longer than the normal interval however not long enough for the coupling interval and the compensatory pause to be 2X the length of the normal interval 

          C_int + P_ex = 2 x N_int = Compensatory, pause is long and the distance between the two normal beats is twice as long the normal interval in the underlying rhythm
           
          where:
           
          Coupling interval = C_int = The interval PP or RR between a normal sinus beat and premature beat
           
          Postextrasystole pause = P_ex = The following pause after a premature beat
           
          Normal interval = N_int = The interval , PP or RR
           
          hope this helps some
           
          Paul
           
           
          Paul Matera, MD

           

           
          In a message dated 1/31/2009 11:20:25 A.M. Eastern Standard Time, lapsklaus@... writes:

          Paul - 

          I do know the Ashman Phenomenon and the underlying mechamisms you describe, but this doesn't help me answer my initial question. Ashman beats usually occur during afib, due to changes in refractory times, and the aberrantly conducted complexes are usually seen after a long-short cycle. The criteria for Ashman Phenomenon were well described by Charles Fisch, and are called the Fisch Criteria if I remember correctly.

          Anyhow, my question was how one can differentiate between compensatory and noncompensatory extrasystolic pauses in a bigeminal pattern during sinus rhythm, since there is no "normal" PP interval to measure by. 

          I agree that it is essential to understand cellular physiology, etc. I like to think that I understand these things very well, but still I can't quite figure out the above. You seem to be skilled at this field, can you help me with an answer? :-)


          On Sat, Jan 31, 2009 at 4:29 PM, <PMATERAMD@...> wrote:

          now we can muddy the waters a little more, ashman's phenomenon is similar to what you are discussing ....knowing how and why this occurs, especially since this phenom occurs after a "normal" beat has already occurred, all this goes back to one of my recent prior posts, i urge all colleagues here that do not fully understand cellular physiology, ie, resting potential, refractory period, excitability, automaticity, all based on sodium in, potassium out, electron charging, all controlled by calcium channels/02/pH, ..., as i said if you understand these issue, understanding the outcome, ie the ecg, is easier,
          stay safe,
          Paul
          Paul Matera, MD, FAEP, FAAIM, EMTP
          Clinical Medicine, Emergency Services, Clinical Electrocardiography, Medical Education
          Director Emeritus - Critical Care Units/Emergency Medicine, Providence Hospital, DC
          Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR Team
          Clinical Associate Professor - Medicine and Health Care Science, GWU, DC
           
          In a message dated 1/30/2009 8:45:34 P.M. Eastern Standard Time, lapsklaus@... writes:

          Niklah -

          I have understood that:
          A compensatory postextrasystolic pause occurs when a premature impulse spreads without depolarizing the atria, and thereby without resetting the SA Node. With a PVC, the early depolarization is normally isolated within the ventricular conduction tissue and therefore the SA Node is oblivious to the occured event and will continue pacing in a timely fashion. By definition, AV dissociation is present at the time the PVC occurs, and therefore the next sinus beat will appear precicely on time. On a surface EKG the coupling interval + the pause will be twice the length of the normal sinus interval.

          Although, a PVC can produce a non-compensatory pause by resetting the SA node via retrograde (VA) conduction to the atria. In comparison, a PAC will normally activate the whole atria including the SA Node, and sinoatrial pacing will therefore be reset. Until the SA Node generates a new impulse, there will be a pause. This pause is not a multiple of the normal interval, and is called non-compensatory when seen on a surface EKG.

          klaus


          On Sat, Jan 31, 2009 at 2:31 AM, Nikiah Nudell <medicnick@...> wrote:

          Klaus what is your physiologic definition of a compensatory pause?

           

          From: ekg_club@yahoogroups.com [mailto:ekg_club@yahoogroups.com] On Behalf Of Klaus Skrudland
          Sent: Friday, January 30, 2009 19:29
          To: ekg_club@yahoogroups.com
          Subject: [ekg_club] postextrasystolic pause

           

          Just an academic question here about the postextrasystolic pause with premature beats. I'm hoping someone can help.

          I've got a strip showing atrial bigeminy, and although PACs usually reset the SA Node and therefore present with noncompensatory pauses, I'd like to prove this. In atrial bigeminy, there is no normal sinus interval, as each sinus beat is followed by a PAC.

          My question is therefore: Can the postextrasystolic pause be determined in a bigeminal rhythm?


          To explain this a bit more thorough:

          To establish whether a postextrasystolic pause is compensatory or noncompensatory, one needs to look at the length of the normal interval and compare it to the added length of the coupling interval and the postextrasystolic pause.

          Compensatory pause: Coupling interval length + postex. pause length = 2 x normal interval (sinus cycle length)
          Noncompensatory pause: Coupling interval length + postex. pause length < 2 x normal interval (sinus cycle length)

          In a bigeminal rhythm, there is no normal interval, so how can I determine whether the pauses are compensatory or not?

          Anyone who can help?


          - klaus




           


          From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.




          --
          Mvh,
          Klaus Nilsen Skrudland

          http://www.sykepleieforum.no
          http://www.lapsklaus.com
          http://ecgblog.wordpress.com
          + 47 99 38 67 55



          From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.




          --
          Mvh,
          Klaus Nilsen Skrudland

          http://www.sykepleieforum.no
          http://www.lapsklaus.com
          http://ecgblog.wordpress.com
          + 47 99 38 67 55

           
           



          From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.



          --
          Mvh,
          Klaus Nilsen Skrudland

          http://www.sykepleieforum.no
          http://www.lapsklaus.com
          http://ecgblog.wordpress.com
          + 47 99 38 67 55





          --
          Mvh,
          Klaus Nilsen Skrudland

          http://www.sykepleieforum.no
          http://www.lapsklaus.com
          http://ecgblog.wordpress.com
          + 47 99 38 67 55



          From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.




          --
          Mvh,
          Klaus Nilsen Skrudland

          http://www.sykepleieforum.no
          http://www.lapsklaus.com
          http://ecgblog.wordpress.com
          + 47 99 38 67 55
        • Nikiah Nudell
          Klaus, By standard practice we use Pwaves as the primary/initial rythm determinant. Think about all the rythms that are based on sinus activity. If you can t
          Message 4 of 17 , Feb 1, 2009
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            Klaus,
            By standard practice we use Pwaves as the primary/initial rythm
            determinant. Think about all the rythms that are based on sinus
            activity.

            If you can't see Pwaves and the QRS is not wide, how do you tell the
            difference between sinus tach, junctional tach, atrial flutter, SVT,
            WPW, etc?

            Some of the other rules like compensatory pauses are also challenging
            unless you have long strips or a normal to compare to.

            With RV apex leads (EGM) what is a normal QRS width/shape and what's
            not? Bundle branch blocks too. I'm not aware of any published rules
            for these, are you?

            Often ectopic beats in RV apex look nearly identical to the normal
            beats. It all depends on the site of initiation. I'm most familiar
            with RVA EGMs -sorry- but am learning that we sometimes take things
            for granted in 12leads.

            Maybe EKGs in Norway are hypothermic? :-)

            BTW, I'm starting to think atrial bigeminy is not uncommon although
            not many ECG examples have been identified here before recent weeks.

            Cheers,
            Nick

            On 02/01/2009, Klaus Skrudland <lapsklaus@...> wrote:
            > Niklah - I'm not sure what you mean when you refer to unreliable P wave
            > detection...? The problem here was just that the bigeminy concealed the base
            > rate/normal interval. I agree, you can't claim a pause to be compensatory
            > nor noncompensatory unless you know the normal intervals. That is
            > established also through the formula that Paul mentioned.
            >
            > And when it comes to paper speed.. I'm sorry if I confuse you. I'd wish the
            > opposite..! I live in Norway, and here there standard 12 lead paper speed is
            > 50 mm/s. I do not know why. Or to put it another way, I can't undetstand why
            > you guys would want to use 25mm/s. When running 50mm/s, it is much easier to
            > spot P waves, to measure intervals and to look for those tiny little things
            > that often tip the diagnosis in the right direction..
            >
            > :-)
            >
            > klaus
            >
            > On Sun, Feb 1, 2009 at 4:59 AM, Nikiah Nudell <medicnick@...> wrote:
            >
            >> Klaus - I have seen this same pattern a number of times as well in EGMs
            >> where you do not have reliable Pwave detection. Its tricky... and we've
            >> written about them before.
            >>
            >> I don't think you can claim it to be "compensatory" unless you actually
            >> know the basal intervals.
            >>
            >> Also, I think you are messing with our minds with 50mm/s strips. Is there
            >> any particular reason why you use this speed?
            >>
            >> Thanks,
            >> Nick
            >>
            >> On Sat, Jan 31, 2009 at 18:00, Klaus Skrudland <lapsklaus@...>wrote:
            >>
            >>> Paul -
            >>>
            >>> It's a pleasure discussing these matters with someone with as much
            >>> insight
            >>> on the issue as you. You're perfectly right, the problem is that there is
            >>> no
            >>> normal interval or no base rate. And you're correct, this is exactly what
            >>> I
            >>> have been banging my head against the wall over.
            >>>
            >>> For now, I've run out of clues on this one.. and as you say, the formula
            >>> unfortunately cannon be used towards solving for X.. There might be
            >>> other
            >>> mathematical relationships between the coupling interval and the pause
            >>> that
            >>> could reveal eventual atrial reset, but that is unknown to me..
            >>>
            >>> Anyway, such discussions as this is very fun anyhow.. My brain got kick
            >>> started too, thanks for participating..! I'll let you (and the rest of
            >>> the
            >>> world) know if I come across anything on this..
            >>>
            >>> The ECG that this problem is derived from is by the way presented in my
            >>> blog right here:
            >>>
            >>> http://ecgblog.wordpress.com/2009/01/31/atrial-unimorph-bigeminy-with-left-axis-deviation/
            >>>
            >>> As you can see, I am trying to establish the ectopic origin of the
            >>> premature contractions, using different approaches. And when I wanted to
            >>> look at the postextrasystolic pause and apply the formula mentioned... I
            >>> couldn't..! :-)
            >>>
            >>> Thanks! Klaus
            >>>
            >>> On Sat, Jan 31, 2009 at 11:24 PM, <PMATERAMD@...> wrote:
            >>>
            >>>> hi again klaus,
            >>>> basically you want to know if we can determine on an ecg wether or not
            >>>> an
            >>>> ecg showing atrial bigeminy reveals a compensatory pause(ie atrial
            >>>> reset) or
            >>>> non-compensatory pause(ie no atrial reset),
            >>>> hmmmm , .., that's a good one,
            >>>>
            >>>> because there is no "normal" interval or known nsr rate, ... that
            >>>> complicates the issue, i would think that on surface ecgs there is not
            >>>> enough "data", ie, we dont have the base rate (so we cant interpolate
            >>>> the
            >>>> N_int) and/or base normal interval (N_int) , ..., as you know
            >>>> mathematically
            >>>> we usually would only need 2 of the 3 components of the formula to
            >>>> calculate
            >>>> the third but we are not solving for X, we are performing a relational
            >>>> equation to determine if the left side is = to right or if left side is
            >>>> >
            >>>> than right, ... i will need to roll this one around for a while more,
            >>>> let me
            >>>> know if you come across a viable answer / theory,
            >>>> great question, gets the old neurons kick started, thanks,
            >>>> Paul
            >>>> *Paul Matera, MD, FAEP, FAAIM, EMTP*
            >>>> Clinical Medicine, Emergency Services, Clinical Electrocardiography,
            >>>> Medical Education
            >>>> Director Emeritus - Critical Care Units/Emergency Medicine, Providence
            >>>> Hospital, DC
            >>>> Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR Team
            >>>> Clinical Associate Professor - Medicine and Health Care Science, GWU, DC
            >>>>
            >>>> In a message dated 1/31/2009 1:36:05 P.M. Eastern Standard Time,
            >>>> lapsklaus@... writes:
            >>>>
            >>>> Thanks a lot, Paul. I appreciate your help, but I'm already familiar
            >>>> with that formula. I've written about it and demonstrated it often in my
            >>>> blog (ecgblog.wordpress.com). I'm glad you mention it though, because
            >>>> I've been trying to apply this formula on an EKG that I have, and I
            >>>> can't
            >>>> figure out which interval to use as N_int. The strip shows an atrial
            >>>> bigeminal rhythm, and actually only shows coupling intervals and
            >>>> postextrasystolic pauses.
            >>>>
            >>>> Take a look here:
            >>>> http://ecgblog.files.wordpress.com/2009/01/atrial_bigeminy_a.jpg
            >>>>
            >>>> Any ideas?
            >>>>
            >>>>
            >>>>
            >>>> With PACs the pause is normally noncompensatory.
            >>>>
            >>>> On Sat, Jan 31, 2009 at 6:50 PM, <PMATERAMD@...> wrote:
            >>>>
            >>>>> if you just want a simple format to calculate odds of compensatory v
            >>>>> non-compensatory you can use the formulas below that help give you the
            >>>>> answer, my prior comments were directed so we can all think through
            >>>>> what is
            >>>>> happening and why
            >>>>>
            >>>>> C_int + P_ex > 2 x N_int = Non-compensatory, pause is longer than the
            >>>>> normal interval however not long enough for the coupling interval and
            >>>>> the
            >>>>> compensatory pause to be 2X the length of the normal interval
            >>>>> C_int + P_ex = 2 x N_int = Compensatory, pause is long and the distance
            >>>>> between the two normal beats is twice as long the normal interval in
            >>>>> the
            >>>>> underlying rhythm
            >>>>>
            >>>>> where:
            >>>>>
            >>>>> Coupling interval = C_int =* *The interval PP or RR between a normal
            >>>>> sinus beat and premature beat
            >>>>> **
            >>>>> Postextrasystole pause = P_ex = The following pause after a premature
            >>>>> beat
            >>>>> **
            >>>>> Normal interval = N_int = The interval , PP or RR
            >>>>>
            >>>>> hope this helps some
            >>>>>
            >>>>> Paul
            >>>>>
            >>>>>
            >>>>> Paul Matera, MD
            >>>>>
            >>>>>
            >>>>>
            >>>>> In a message dated 1/31/2009 11:20:25 A.M. Eastern Standard Time,
            >>>>> lapsklaus@... writes:
            >>>>>
            >>>>> Paul -
            >>>>> I do know the Ashman Phenomenon and the underlying mechamisms you
            >>>>> describe, but this doesn't help me answer my initial question. Ashman
            >>>>> beats
            >>>>> usually occur during afib, due to changes in refractory times, and the
            >>>>> aberrantly conducted complexes are usually seen after a long-short
            >>>>> cycle.
            >>>>> The criteria for Ashman Phenomenon were well described by Charles
            >>>>> Fisch, and
            >>>>> are called the Fisch Criteria if I remember correctly.
            >>>>>
            >>>>> Anyhow, my question was how one can differentiate between compensatory
            >>>>> and noncompensatory extrasystolic pauses in a bigeminal pattern during
            >>>>> sinus
            >>>>> rhythm, since there is no "normal" PP interval to measure by.
            >>>>>
            >>>>> I agree that it is essential to understand cellular physiology, etc. I
            >>>>> like to think that I understand these things very well, but still I
            >>>>> can't
            >>>>> quite figure out the above. You seem to be skilled at this field, can
            >>>>> you
            >>>>> help me with an answer? :-)
            >>>>>
            >>>>>
            >>>>> On Sat, Jan 31, 2009 at 4:29 PM, <PMATERAMD@...> wrote:
            >>>>>
            >>>>>> now we can muddy the waters a little more, ashman's phenomenon is
            >>>>>> similar to what you are discussing ....knowing how and why this
            >>>>>> occurs,
            >>>>>> especially since this phenom occurs after a "normal" beat has already
            >>>>>> occurred, all this goes back to one of my recent prior posts, i urge
            >>>>>> all
            >>>>>> colleagues here that do not fully understand cellular physiology, ie,
            >>>>>> resting potential, refractory period, excitability, automaticity, all
            >>>>>> based
            >>>>>> on sodium in, potassium out, electron charging, all controlled by
            >>>>>> calcium
            >>>>>> channels/02/pH, ..., as i said if you understand these issue,
            >>>>>> understanding
            >>>>>> the outcome, ie the ecg, is easier,
            >>>>>> stay safe,
            >>>>>> Paul
            >>>>>> *Paul Matera, MD, FAEP, FAAIM, EMTP*
            >>>>>> Clinical Medicine, Emergency Services, Clinical Electrocardiography,
            >>>>>> Medical Education
            >>>>>> Director Emeritus - Critical Care Units/Emergency Medicine, Providence
            >>>>>> Hospital, DC
            >>>>>> Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR
            >>>>>> Team
            >>>>>> Clinical Associate Professor - Medicine and Health Care Science, GWU,
            >>>>>> DC
            >>>>>>
            >>>>>> In a message dated 1/30/2009 8:45:34 P.M. Eastern Standard Time,
            >>>>>> lapsklaus@... writes:
            >>>>>>
            >>>>>> Niklah -
            >>>>>>
            >>>>>> I have understood that:
            >>>>>> A compensatory postextrasystolic pause occurs when a premature impulse
            >>>>>> spreads without depolarizing the atria, and thereby without resetting
            >>>>>> the SA
            >>>>>> Node. With a PVC, the early depolarization is normally isolated within
            >>>>>> the
            >>>>>> ventricular conduction tissue and therefore the SA Node is oblivious
            >>>>>> to the
            >>>>>> occured event and will continue pacing in a timely fashion. By
            >>>>>> definition,
            >>>>>> AV dissociation is present at the time the PVC occurs, and therefore
            >>>>>> the
            >>>>>> next sinus beat will appear precicely on time. On a surface EKG the
            >>>>>> coupling
            >>>>>> interval + the pause will be twice the length of the normal sinus
            >>>>>> interval.
            >>>>>>
            >>>>>> Although, a PVC can produce a non-compensatory pause by resetting the
            >>>>>> SA node via retrograde (VA) conduction to the atria. In comparison, a
            >>>>>> PAC
            >>>>>> will normally activate the whole atria including the SA Node, and
            >>>>>> sinoatrial
            >>>>>> pacing will therefore be reset. Until the SA Node generates a new
            >>>>>> impulse,
            >>>>>> there will be a pause. This pause is not a multiple of the normal
            >>>>>> interval,
            >>>>>> and is called non-compensatory when seen on a surface EKG.
            >>>>>>
            >>>>>> klaus
            >>>>>>
            >>>>>>
            >>>>>> On Sat, Jan 31, 2009 at 2:31 AM, Nikiah Nudell
            >>>>>> <medicnick@...>wrote:
            >>>>>>
            >>>>>>> Klaus what is your physiologic definition of a compensatory pause?
            >>>>>>>
            >>>>>>>
            >>>>>>>
            >>>>>>> *From:* ekg_club@yahoogroups.com [mailto:ekg_club@yahoogroups.com]
            >>>>>>> *On
            >>>>>>> Behalf Of *Klaus Skrudland
            >>>>>>> *Sent:* Friday, January 30, 2009 19:29
            >>>>>>> *To:* ekg_club@yahoogroups.com
            >>>>>>> *Subject:* [ekg_club] postextrasystolic pause
            >>>>>>>
            >>>>>>>
            >>>>>>>
            >>>>>>> Just an academic question here about the postextrasystolic pause with
            >>>>>>> premature beats. I'm hoping someone can help.
            >>>>>>>
            >>>>>>> I've got a strip showing atrial bigeminy, and although PACs usually
            >>>>>>> reset the SA Node and therefore present with noncompensatory pauses,
            >>>>>>> I'd
            >>>>>>> like to prove this. In atrial bigeminy, there is no normal sinus
            >>>>>>> interval,
            >>>>>>> as each sinus beat is followed by a PAC.
            >>>>>>>
            >>>>>>> My question is therefore: Can the postextrasystolic pause be
            >>>>>>> determined in a bigeminal rhythm?
            >>>>>>>
            >>>>>>>
            >>>>>>> To explain this a bit more thorough:
            >>>>>>>
            >>>>>>> To establish whether a postextrasystolic pause is compensatory or
            >>>>>>> noncompensatory, one needs to look at the length of the normal
            >>>>>>> interval and
            >>>>>>> compare it to the added length of the coupling interval and the
            >>>>>>> postextrasystolic pause.
            >>>>>>>
            >>>>>>> Compensatory pause: Coupling interval length + postex. pause length =
            >>>>>>> 2 x normal interval (sinus cycle length)
            >>>>>>> Noncompensatory pause: Coupling interval length + postex. pause
            >>>>>>> length
            >>>>>>> < 2 x normal interval (sinus cycle length)
            >>>>>>>
            >>>>>>> In a bigeminal rhythm, there is no normal interval, so how can I
            >>>>>>> determine whether the pauses are compensatory or not?
            >>>>>>>
            >>>>>>> Anyone who can help?
            >>>>>>>
            >>>>>>>
            >>>>>>> - klaus
            >>>>>>>
            >>>>>>>
            >>>>>>
            >>>>>>
            >>>>>> --
            >>>>>> Mvh,
            >>>>>> Klaus Nilsen Skrudland
            >>>>>>
            >>>>>> http://www.sykepleieforum.no
            >>>>>> http://www.lapsklaus.com
            >>>>>> http://ecgblog.wordpress.com
            >>>>>> + 47 99 38 67 55
            >>>>>>
            >>>>>>
            >>>>>>
            >>>>>>
            >>>>>> ------------------------------
            >>>>>> From Wall Street to Main Street and everywhere in between, stay
            >>>>>> up-to-date with the latest
            >>>>>> news<http://aol.com/?ncid=emlcntaolcom00000023>
            >>>>>> .
            >>>>>>
            >>>>>>
            >>>>>
            >>>>>
            >>>>> --
            >>>>> Mvh,
            >>>>> Klaus Nilsen Skrudland
            >>>>>
            >>>>> http://www.sykepleieforum.no
            >>>>> http://www.lapsklaus.com
            >>>>> http://ecgblog.wordpress.com
            >>>>> + 47 99 38 67 55
            >>>>>
            >>>>>
            >>>>> ------------------------------
            >>>>> From Wall Street to Main Street and everywhere in between, stay
            >>>>> up-to-date with the latest
            >>>>> news<http://aol.com/?ncid=emlcntaolcom00000023>
            >>>>> .
            >>>>>
            >>>>>
            >>>>
            >>>>
            >>>> --
            >>>> Mvh,
            >>>> Klaus Nilsen Skrudland
            >>>>
            >>>> http://www.sykepleieforum.no
            >>>> http://www.lapsklaus.com
            >>>> http://ecgblog.wordpress.com
            >>>> + 47 99 38 67 55
            >>>>
            >>>>
            >>>> **
            >>>>
            >>>>
            >>>>
            >>>> ------------------------------
            >>>> From Wall Street to Main Street and everywhere in between, stay
            >>>> up-to-date with the latest
            >>>> news<http://aol.com/?ncid=emlcntaolcom00000023>
            >>>> .
            >>>>
            >>>
            >>>
            >>>
            >>> --
            >>> Mvh,
            >>> Klaus Nilsen Skrudland
            >>>
            >>> http://www.sykepleieforum.no
            >>> http://www.lapsklaus.com
            >>> http://ecgblog.wordpress.com
            >>> + 47 99 38 67 55
            >>>
            >>>
            >>
            >>
            >
            >
            >
            > --
            > Mvh,
            > Klaus Nilsen Skrudland
            >
            > http://www.sykepleieforum.no
            > http://www.lapsklaus.com
            > http://ecgblog.wordpress.com
            > + 47 99 38 67 55
            >

            --
            Sent from my mobile device
          • Klaus Skrudland
            Yes, I do know why you need to see P waves to differentiate rhythms... I just didn t know why you mentioned P wave detection in the discussion about the
            Message 5 of 17 , Feb 1, 2009
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              Yes, I do know why you need to see P waves to differentiate rhythms... I just didn't know why you mentioned P wave detection in the discussion about the postextrasystolic pause with atrial bigeminy. The P waves were clearly visible, it was the missing normal interval that was the problem. Anyway, that problem is to remain unsolved for now.

              With postextrasystolic pauses, you do not necessary need a long strip. If the strip contains a normal (ie. sinus cycle) interval interrupted by a premature beat, then the type of pause can be determined. Comparing with an older strip from the same patient will not help you with this, as the "normal" interval (ie. a normal sinus cycle) will always vary. You need to measure the normal interval in the same strip as the premature beat. 

              Atrial arrhythmias are very common, and so is both PACs, atrial bigeminy and trigeminy. They are also usually easy to identify, using simple rules. 

              klaus

              On Sun, Feb 1, 2009 at 2:21 PM, Nikiah Nudell <medicnick@...> wrote:

              Klaus,
              By standard practice we use Pwaves as the primary/initial rythm
              determinant. Think about all the rythms that are based on sinus
              activity.

              If you can't see Pwaves and the QRS is not wide, how do you tell the
              difference between sinus tach, junctional tach, atrial flutter, SVT,
              WPW, etc?

              Some of the other rules like compensatory pauses are also challenging
              unless you have long strips or a normal to compare to.

              With RV apex leads (EGM) what is a normal QRS width/shape and what's
              not? Bundle branch blocks too. I'm not aware of any published rules
              for these, are you?

              Often ectopic beats in RV apex look nearly identical to the normal
              beats. It all depends on the site of initiation. I'm most familiar
              with RVA EGMs -sorry- but am learning that we sometimes take things
              for granted in 12leads.

              Maybe EKGs in Norway are hypothermic? :-)

              BTW, I'm starting to think atrial bigeminy is not uncommon although
              not many ECG examples have been identified here before recent weeks.

              Cheers,
              Nick



              On 02/01/2009, Klaus Skrudland <lapsklaus@...> wrote:
              > Niklah - I'm not sure what you mean when you refer to unreliable P wave
              > detection...? The problem here was just that the bigeminy concealed the base
              > rate/normal interval. I agree, you can't claim a pause to be compensatory
              > nor noncompensatory unless you know the normal intervals. That is
              > established also through the formula that Paul mentioned.
              >
              > And when it comes to paper speed.. I'm sorry if I confuse you. I'd wish the
              > opposite..! I live in Norway, and here there standard 12 lead paper speed is
              > 50 mm/s. I do not know why. Or to put it another way, I can't undetstand why
              > you guys would want to use 25mm/s. When running 50mm/s, it is much easier to
              > spot P waves, to measure intervals and to look for those tiny little things
              > that often tip the diagnosis in the right direction..
              >
              > :-)
              >
              > klaus
              >
              > On Sun, Feb 1, 2009 at 4:59 AM, Nikiah Nudell <medicnick@...> wrote:
              >
              >> Klaus - I have seen this same pattern a number of times as well in EGMs
              >> where you do not have reliable Pwave detection. Its tricky... and we've
              >> written about them before.
              >>
              >> I don't think you can claim it to be "compensatory" unless you actually
              >> know the basal intervals.
              >>
              >> Also, I think you are messing with our minds with 50mm/s strips. Is there
              >> any particular reason why you use this speed?
              >>
              >> Thanks,
              >> Nick
              >>
              >> On Sat, Jan 31, 2009 at 18:00, Klaus Skrudland <lapsklaus@...>wrote:
              >>
              >>> Paul -
              >>>
              >>> It's a pleasure discussing these matters with someone with as much
              >>> insight
              >>> on the issue as you. You're perfectly right, the problem is that there is
              >>> no
              >>> normal interval or no base rate. And you're correct, this is exactly what
              >>> I
              >>> have been banging my head against the wall over.
              >>>
              >>> For now, I've run out of clues on this one.. and as you say, the formula
              >>> unfortunately cannon be used towards solving for X.. There might be
              >>> other
              >>> mathematical relationships between the coupling interval and the pause
              >>> that
              >>> could reveal eventual atrial reset, but that is unknown to me..
              >>>
              >>> Anyway, such discussions as this is very fun anyhow.. My brain got kick
              >>> started too, thanks for participating..! I'll let you (and the rest of
              >>> the
              >>> world) know if I come across anything on this..
              >>>
              >>> The ECG that this problem is derived from is by the way presented in my
              >>> blog right here:
              >>>
              >>> http://ecgblog.wordpress.com/2009/01/31/atrial-unimorph-bigeminy-with-left-axis-deviation/
              >>>
              >>> As you can see, I am trying to establish the ectopic origin of the
              >>> premature contractions, using different approaches. And when I wanted to
              >>> look at the postextrasystolic pause and apply the formula mentioned... I
              >>> couldn't..! :-)
              >>>
              >>> Thanks! Klaus
              >>>
              >>> On Sat, Jan 31, 2009 at 11:24 PM, <PMATERAMD@...> wrote:
              >>>
              >>>> hi again klaus,
              >>>> basically you want to know if we can determine on an ecg wether or not
              >>>> an
              >>>> ecg showing atrial bigeminy reveals a compensatory pause(ie atrial
              >>>> reset) or
              >>>> non-compensatory pause(ie no atrial reset),
              >>>> hmmmm , .., that's a good one,
              >>>>
              >>>> because there is no "normal" interval or known nsr rate, ... that
              >>>> complicates the issue, i would think that on surface ecgs there is not
              >>>> enough "data", ie, we dont have the base rate (so we cant interpolate
              >>>> the
              >>>> N_int) and/or base normal interval (N_int) , ..., as you know
              >>>> mathematically
              >>>> we usually would only need 2 of the 3 components of the formula to
              >>>> calculate
              >>>> the third but we are not solving for X, we are performing a relational
              >>>> equation to determine if the left side is = to right or if left side is
              >>>> >
              >>>> than right, ... i will need to roll this one around for a while more,
              >>>> let me
              >>>> know if you come across a viable answer / theory,
              >>>> great question, gets the old neurons kick started, thanks,
              >>>> Paul
              >>>> *Paul Matera, MD, FAEP, FAAIM, EMTP*
              >>>> Clinical Medicine, Emergency Services, Clinical Electrocardiography,
              >>>> Medical Education
              >>>> Director Emeritus - Critical Care Units/Emergency Medicine, Providence
              >>>> Hospital, DC
              >>>> Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR Team
              >>>> Clinical Associate Professor - Medicine and Health Care Science, GWU, DC
              >>>>
              >>>> In a message dated 1/31/2009 1:36:05 P.M. Eastern Standard Time,
              >>>> lapsklaus@... writes:
              >>>>
              >>>> Thanks a lot, Paul. I appreciate your help, but I'm already familiar
              >>>> with that formula. I've written about it and demonstrated it often in my
              >>>> blog (ecgblog.wordpress.com). I'm glad you mention it though, because
              >>>> I've been trying to apply this formula on an EKG that I have, and I
              >>>> can't
              >>>> figure out which interval to use as N_int. The strip shows an atrial
              >>>> bigeminal rhythm, and actually only shows coupling intervals and
              >>>> postextrasystolic pauses.
              >>>>
              >>>> Take a look here:
              >>>> http://ecgblog.files.wordpress.com/2009/01/atrial_bigeminy_a.jpg
              >>>>
              >>>> Any ideas?
              >>>>
              >>>>
              >>>>
              >>>> With PACs the pause is normally noncompensatory.
              >>>>
              >>>> On Sat, Jan 31, 2009 at 6:50 PM, <PMATERAMD@...> wrote:
              >>>>
              >>>>> if you just want a simple format to calculate odds of compensatory v
              >>>>> non-compensatory you can use the formulas below that help give you the
              >>>>> answer, my prior comments were directed so we can all think through
              >>>>> what is
              >>>>> happening and why
              >>>>>
              >>>>> C_int + P_ex > 2 x N_int = Non-compensatory, pause is longer than the
              >>>>> normal interval however not long enough for the coupling interval and
              >>>>> the
              >>>>> compensatory pause to be 2X the length of the normal interval
              >>>>> C_int + P_ex = 2 x N_int = Compensatory, pause is long and the distance
              >>>>> between the two normal beats is twice as long the normal interval in
              >>>>> the
              >>>>> underlying rhythm
              >>>>>
              >>>>> where:
              >>>>>
              >>>>> Coupling interval = C_int =* *The interval PP or RR between a normal
              >>>>> sinus beat and premature beat
              >>>>> **
              >>>>> Postextrasystole pause = P_ex = The following pause after a premature
              >>>>> beat
              >>>>> **
              >>>>> Normal interval = N_int = The interval , PP or RR
              >>>>>
              >>>>> hope this helps some
              >>>>>
              >>>>> Paul
              >>>>>
              >>>>>
              >>>>> Paul Matera, MD
              >>>>>
              >>>>>
              >>>>>
              >>>>> In a message dated 1/31/2009 11:20:25 A.M. Eastern Standard Time,
              >>>>> lapsklaus@... writes:
              >>>>>
              >>>>> Paul -
              >>>>> I do know the Ashman Phenomenon and the underlying mechamisms you
              >>>>> describe, but this doesn't help me answer my initial question. Ashman
              >>>>> beats
              >>>>> usually occur during afib, due to changes in refractory times, and the
              >>>>> aberrantly conducted complexes are usually seen after a long-short
              >>>>> cycle.
              >>>>> The criteria for Ashman Phenomenon were well described by Charles
              >>>>> Fisch, and
              >>>>> are called the Fisch Criteria if I remember correctly.
              >>>>>
              >>>>> Anyhow, my question was how one can differentiate between compensatory
              >>>>> and noncompensatory extrasystolic pauses in a bigeminal pattern during
              >>>>> sinus
              >>>>> rhythm, since there is no "normal" PP interval to measure by.
              >>>>>
              >>>>> I agree that it is essential to understand cellular physiology, etc. I
              >>>>> like to think that I understand these things very well, but still I
              >>>>> can't
              >>>>> quite figure out the above. You seem to be skilled at this field, can
              >>>>> you
              >>>>> help me with an answer? :-)
              >>>>>
              >>>>>
              >>>>> On Sat, Jan 31, 2009 at 4:29 PM, <PMATERAMD@...> wrote:
              >>>>>
              >>>>>> now we can muddy the waters a little more, ashman's phenomenon is
              >>>>>> similar to what you are discussing ....knowing how and why this
              >>>>>> occurs,
              >>>>>> especially since this phenom occurs after a "normal" beat has already
              >>>>>> occurred, all this goes back to one of my recent prior posts, i urge
              >>>>>> all
              >>>>>> colleagues here that do not fully understand cellular physiology, ie,
              >>>>>> resting potential, refractory period, excitability, automaticity, all
              >>>>>> based
              >>>>>> on sodium in, potassium out, electron charging, all controlled by
              >>>>>> calcium
              >>>>>> channels/02/pH, ..., as i said if you understand these issue,
              >>>>>> understanding
              >>>>>> the outcome, ie the ecg, is easier,
              >>>>>> stay safe,
              >>>>>> Paul
              >>>>>> *Paul Matera, MD, FAEP, FAAIM, EMTP*
              >>>>>> Clinical Medicine, Emergency Services, Clinical Electrocardiography,
              >>>>>> Medical Education
              >>>>>> Director Emeritus - Critical Care Units/Emergency Medicine, Providence
              >>>>>> Hospital, DC
              >>>>>> Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR
              >>>>>> Team
              >>>>>> Clinical Associate Professor - Medicine and Health Care Science, GWU,
              >>>>>> DC
              >>>>>>
              >>>>>> In a message dated 1/30/2009 8:45:34 P.M. Eastern Standard Time,
              >>>>>> lapsklaus@... writes:
              >>>>>>
              >>>>>> Niklah -
              >>>>>>
              >>>>>> I have understood that:
              >>>>>> A compensatory postextrasystolic pause occurs when a premature impulse
              >>>>>> spreads without depolarizing the atria, and thereby without resetting
              >>>>>> the SA
              >>>>>> Node. With a PVC, the early depolarization is normally isolated within
              >>>>>> the
              >>>>>> ventricular conduction tissue and therefore the SA Node is oblivious
              >>>>>> to the
              >>>>>> occured event and will continue pacing in a timely fashion. By
              >>>>>> definition,
              >>>>>> AV dissociation is present at the time the PVC occurs, and therefore
              >>>>>> the
              >>>>>> next sinus beat will appear precicely on time. On a surface EKG the
              >>>>>> coupling
              >>>>>> interval + the pause will be twice the length of the normal sinus
              >>>>>> interval.
              >>>>>>
              >>>>>> Although, a PVC can produce a non-compensatory pause by resetting the
              >>>>>> SA node via retrograde (VA) conduction to the atria. In comparison, a
              >>>>>> PAC
              >>>>>> will normally activate the whole atria including the SA Node, and
              >>>>>> sinoatrial
              >>>>>> pacing will therefore be reset. Until the SA Node generates a new
              >>>>>> impulse,
              >>>>>> there will be a pause. This pause is not a multiple of the normal
              >>>>>> interval,
              >>>>>> and is called non-compensatory when seen on a surface EKG.
              >>>>>>
              >>>>>> klaus
              >>>>>>
              >>>>>>
              >>>>>> On Sat, Jan 31, 2009 at 2:31 AM, Nikiah Nudell
              >>>>>> <medicnick@...>wrote:
              >>>>>>
              >>>>>>> Klaus what is your physiologic definition of a compensatory pause?
              >>>>>>>
              >>>>>>>
              >>>>>>>
              >>>>>>> *From:* ekg_club@yahoogroups.com [mailto:ekg_club@yahoogroups.com]
              >>>>>>> *On
              >>>>>>> Behalf Of *Klaus Skrudland
              >>>>>>> *Sent:* Friday, January 30, 2009 19:29
              >>>>>>> *To:* ekg_club@yahoogroups.com
              >>>>>>> *Subject:* [ekg_club] postextrasystolic pause
              >>>>>>>
              >>>>>>>
              >>>>>>>
              >>>>>>> Just an academic question here about the postextrasystolic pause with
              >>>>>>> premature beats. I'm hoping someone can help.
              >>>>>>>
              >>>>>>> I've got a strip showing atrial bigeminy, and although PACs usually
              >>>>>>> reset the SA Node and therefore present with noncompensatory pauses,
              >>>>>>> I'd
              >>>>>>> like to prove this. In atrial bigeminy, there is no normal sinus
              >>>>>>> interval,
              >>>>>>> as each sinus beat is followed by a PAC.
              >>>>>>>
              >>>>>>> My question is therefore: Can the postextrasystolic pause be
              >>>>>>> determined in a bigeminal rhythm?
              >>>>>>>
              >>>>>>>
              >>>>>>> To explain this a bit more thorough:
              >>>>>>>
              >>>>>>> To establish whether a postextrasystolic pause is compensatory or
              >>>>>>> noncompensatory, one needs to look at the length of the normal
              >>>>>>> interval and
              >>>>>>> compare it to the added length of the coupling interval and the
              >>>>>>> postextrasystolic pause.
              >>>>>>>
              >>>>>>> Compensatory pause: Coupling interval length + postex. pause length =
              >>>>>>> 2 x normal interval (sinus cycle length)
              >>>>>>> Noncompensatory pause: Coupling interval length + postex. pause
              >>>>>>> length
              >>>>>>> < 2 x normal interval (sinus cycle length)
              >>>>>>>
              >>>>>>> In a bigeminal rhythm, there is no normal interval, so how can I
              >>>>>>> determine whether the pauses are compensatory or not?
              >>>>>>>
              >>>>>>> Anyone who can help?
              >>>>>>>
              >>>>>>>
              >>>>>>> - klaus
              >>>>>>>
              >>>>>>>
              >>>>>>
              >>>>>>
              >>>>>> --
              >>>>>> Mvh,
              >>>>>> Klaus Nilsen Skrudland
              >>>>>>
              >>>>>> http://www.sykepleieforum.no
              >>>>>> http://www.lapsklaus.com
              >>>>>> http://ecgblog.wordpress.com
              >>>>>> + 47 99 38 67 55
              >>>>>>
              >>>>>>
              >>>>>>
              >>>>>>
              >>>>>> ------------------------------
              >>>>>> From Wall Street to Main Street and everywhere in between, stay
              >>>>>> up-to-date with the latest
              >>>>>> news<http://aol.com/?ncid=emlcntaolcom00000023>
              >>>>>> .
              >>>>>>
              >>>>>>
              >>>>>
              >>>>>
              >>>>> --

              >>>>> Mvh,
              >>>>> Klaus Nilsen Skrudland
              >>>>>
              >>>>> http://www.sykepleieforum.no
              >>>>> http://www.lapsklaus.com
              >>>>> http://ecgblog.wordpress.com
              >>>>> + 47 99 38 67 55
              >>>>>
              >>>>>
              >>>>> ------------------------------
              >>>>> From Wall Street to Main Street and everywhere in between, stay
              >>>>> up-to-date with the latest
              >>>>> news<http://aol.com/?ncid=emlcntaolcom00000023>
              >>>>> .
              >>>>>
              >>>>>
              >>>>
              >>>>
              >>>> --

              >>>> Mvh,
              >>>> Klaus Nilsen Skrudland
              >>>>
              >>>> http://www.sykepleieforum.no
              >>>> http://www.lapsklaus.com
              >>>> http://ecgblog.wordpress.com
              >>>> + 47 99 38 67 55
              >>>>
              >>>>
              >>>> **
              >>>>
              >>>>
              >>>>
              >>>> ------------------------------
              >>>> From Wall Street to Main Street and everywhere in between, stay
              >>>> up-to-date with the latest
              >>>> news<http://aol.com/?ncid=emlcntaolcom00000023>
              >>>> .
              >>>>
              >>>
              >>>
              >>>
              >>> --

              >>> Mvh,
              >>> Klaus Nilsen Skrudland
              >>>
              >>> http://www.sykepleieforum.no
              >>> http://www.lapsklaus.com
              >>> http://ecgblog.wordpress.com
              >>> + 47 99 38 67 55
              >>>
              >>>
              >>
              >>
              >
              >
              >
              > --

              > Mvh,
              > Klaus Nilsen Skrudland
              >
              > http://www.sykepleieforum.no
              > http://www.lapsklaus.com
              > http://ecgblog.wordpress.com
              > + 47 99 38 67 55
              >

              --
              Sent from my mobile device




              --
              Mvh,
              Klaus Nilsen Skrudland

              http://www.sykepleieforum.no
              http://www.lapsklaus.com
              http://ecgblog.wordpress.com
              + 47 99 38 67 55
            • Teresa M
              For our ablations, we always run at 50 mm....drives me crazy because everyone in there is so much better at reading that speed and I hate it when everyone
              Message 6 of 17 , Feb 1, 2009
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                For our ablations, we always run at 50 mm....drives me crazy because everyone in there is so much better at reading that speed and I hate it when everyone goes...ahhhhh....thank goodness I have my handy dandy little defib going at my speed that I am used to...:-)

                --- On Sun, 2/1/09, PMATERAMD@... <PMATERAMD@...> wrote:
                From: PMATERAMD@... <PMATERAMD@...>
                Subject: Re: [ekg_club] postextrasystolic pause
                To: ekg_club@yahoogroups.com
                Date: Sunday, February 1, 2009, 7:15 AM

                on this issue of paper speed and subsequently mV amplitude, as you know the US std is 25mm/sec  and 10mm/mV,   I often ask for 12 leads and 3 lead rhythm strips the be run at 50mm/sec and 20mm/mV  which helps magnify and bring out subtle "p", allows more accurate intervals, etc, just be sure the ecg is clearly marked as 50mm , or you will get a call from the next consultant asking why your pt with a heart rate of 30 isnt being treated ,
                 
                paul
                 
                In a message dated 2/1/2009 8:02:39 A.M. Eastern Standard Time, lapsklaus@gmail. com writes:
                Niklah - 
                I'm not sure what you mean when you refer to unreliable P wave detection... ? The problem here was just that the bigeminy concealed the base rate/normal interval. I agree, you can't claim a pause to be compensatory nor noncompensatory unless you know the normal intervals. That is established also through the formula that Paul mentioned. 

                And when it comes to paper speed.. I'm sorry if I confuse you. I'd wish the opposite..! I live in Norway, and here there standard 12 lead paper speed is 50 mm/s. I do not know why. Or to put it another way, I can't undetstand why you guys would want to use 25mm/s. When running 50mm/s, it is much easier to spot P waves, to measure intervals and to look for those tiny little things that often tip the diagnosis in the right direction.. 

                :-)

                klaus

                On Sun, Feb 1, 2009 at 4:59 AM, Nikiah Nudell <medicnick@gmail. com> wrote:
                Klaus - I have seen this same pattern a number of times as well in EGMs where you do not have reliable Pwave detection. Its tricky... and we've written about them before.
                 
                I don't think you can claim it to be "compensatory" unless you actually know the basal intervals.
                 
                Also, I think you are messing with our minds with 50mm/s strips. Is there any particular reason why you use this speed?
                 
                Thanks,
                Nick

                On Sat, Jan 31, 2009 at 18:00, Klaus Skrudland <lapsklaus@gmail. com> wrote:
                Paul - 

                It's a pleasure discussing these matters with someone with as much insight on the issue as you. You're perfectly right, the problem is that there is no normal interval or no base rate. And you're correct, this is exactly what I have been banging my head against the wall over. 

                For now, I've run out of clues on this one.. and as you say, the formula unfortunately cannon be used towards solving for X..  There might be other mathematical relationships between the coupling interval and the pause that could reveal eventual atrial reset, but that is unknown to me.. 

                Anyway, such discussions as this is very fun anyhow.. My brain got kick started too, thanks for participating. .! I'll let you (and the rest of the world) know if I come across anything on this..

                The ECG that this problem is derived from is by the way presented in my blog right here: 

                 As you can see, I am trying to establish the ectopic origin of the premature contractions, using different approaches. And when I wanted to look at the postextrasystolic pause and apply the formula mentioned... I couldn't..! :-)

                Thanks! Klaus

                On Sat, Jan 31, 2009 at 11:24 PM, <PMATERAMD@aol. com> wrote:
                hi again klaus,
                basically you want to know if we can determine on an ecg wether or not an ecg showing atrial bigeminy reveals a compensatory pause(ie atrial reset) or non-compensatory pause(ie no atrial reset),
                hmmmm ,  .., that's a good one,
                 
                because there is no "normal" interval or known nsr rate, ... that complicates the issue, i would think that on surface ecgs there is not enough "data", ie, we dont have the base rate (so we cant interpolate the N_int) and/or base normal interval (N_int) , ..., as you know mathematically we usually would only need 2 of the 3 components of the formula to calculate the third but we are not solving for X, we are performing a relational equation to determine if the left side is = to right or if left side is > than right, ... i will need to roll this one around for a while more, let me know if you come across a viable answer / theory,
                great question, gets the old neurons kick started, thanks,
                Paul
                Paul Matera, MD, FAEP, FAAIM, EMTP
                Clinical Medicine, Emergency Services, Clinical Electrocardiography , Medical Education
                Director Emeritus - Critical Care Units/Emergency Medicine, Providence Hospital, DC
                Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR Team
                Clinical Associate Professor - Medicine and Health Care Science, GWU, DC
                 
                In a message dated 1/31/2009 1:36:05 P.M. Eastern Standard Time, lapsklaus@gmail. com writes:
                Thanks a lot, Paul. I appreciate your help, but I'm already familiar with that formula. I've written about it and demonstrated it often in my blog (ecgblog.wordpress. com). I'm glad you mention it though, because I've been trying to apply this formula on an EKG that I have, and I can't figure out which interval to use as N_int. The strip shows an atrial bigeminal rhythm, and actually only shows coupling intervals and postextrasystolic pauses. 


                Any ideas?



                With PACs the pause is normally noncompensatory. 

                On Sat, Jan 31, 2009 at 6:50 PM, <PMATERAMD@aol. com> wrote:
                if you just want a simple format to calculate odds of compensatory v non-compensatory you can use the formulas below that help give you the answer, my prior comments were directed so we can all think through what is happening and why
                C_int + P_ex > 2 x N_int = Non-compensatory, pause is longer than the normal interval however not long enough for the coupling interval and the compensatory pause to be 2X the length of the normal interval 
                C_int + P_ex = 2 x N_int = Compensatory, pause is long and the distance between the two normal beats is twice as long the normal interval in the underlying rhythm
                 
                where:
                 
                Coupling interval = C_int = The interval PP or RR between a normal sinus beat and premature beat
                 
                Postextrasystole pause = P_ex = The following pause after a premature beat
                 
                Normal interval = N_int = The interval , PP or RR
                 
                hope this helps some
                 
                Paul
                 
                 
                Paul Matera, MD
                 
                 
                In a message dated 1/31/2009 11:20:25 A.M. Eastern Standard Time, lapsklaus@gmail. com writes:
                Paul - 
                I do know the Ashman Phenomenon and the underlying mechamisms you describe, but this doesn't help me answer my initial question. Ashman beats usually occur during afib, due to changes in refractory times, and the aberrantly conducted complexes are usually seen after a long-short cycle. The criteria for Ashman Phenomenon were well described by Charles Fisch, and are called the Fisch Criteria if I remember correctly.

                Anyhow, my question was how one can differentiate between compensatory and noncompensatory extrasystolic pauses in a bigeminal pattern during sinus rhythm, since there is no "normal" PP interval to measure by. 

                I agree that it is essential to understand cellular physiology, etc. I like to think that I understand these things very well, but still I can't quite figure out the above. You seem to be skilled at this field, can you help me with an answer? :-)


                On Sat, Jan 31, 2009 at 4:29 PM, <PMATERAMD@aol. com> wrote:
                now we can muddy the waters a little more, ashman's phenomenon is similar to what you are discussing ....knowing how and why this occurs, especially since this phenom occurs after a "normal" beat has already occurred, all this goes back to one of my recent prior posts, i urge all colleagues here that do not fully understand cellular physiology, ie, resting potential, refractory period, excitability, automaticity, all based on sodium in, potassium out, electron charging, all controlled by calcium channels/02/ pH, ..., as i said if you understand these issue, understanding the outcome, ie the ecg, is easier,
                stay safe,
                Paul
                Paul Matera, MD, FAEP, FAAIM, EMTP
                Clinical Medicine, Emergency Services, Clinical Electrocardiography , Medical Education
                Director Emeritus - Critical Care Units/Emergency Medicine, Providence Hospital, DC
                Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR Team
                Clinical Associate Professor - Medicine and Health Care Science, GWU, DC
                 
                In a message dated 1/30/2009 8:45:34 P.M. Eastern Standard Time, lapsklaus@gmail. com writes:
                Niklah -

                I have understood that:
                A compensatory postextrasystolic pause occurs when a premature impulse spreads without depolarizing the atria, and thereby without resetting the SA Node. With a PVC, the early depolarization is normally isolated within the ventricular conduction tissue and therefore the SA Node is oblivious to the occured event and will continue pacing in a timely fashion. By definition, AV dissociation is present at the time the PVC occurs, and therefore the next sinus beat will appear precicely on time. On a surface EKG the coupling interval + the pause will be twice the length of the normal sinus interval.

                Although, a PVC can produce a non-compensatory pause by resetting the SA node via retrograde (VA) conduction to the atria. In comparison, a PAC will normally activate the whole atria including the SA Node, and sinoatrial pacing will therefore be reset. Until the SA Node generates a new impulse, there will be a pause. This pause is not a multiple of the normal interval, and is called non-compensatory when seen on a surface EKG.

                klaus


                On Sat, Jan 31, 2009 at 2:31 AM, Nikiah Nudell <medicnick@gmail. com> wrote:
                Klaus what is your physiologic definition of a compensatory pause?
                 
                From: ekg_club@yahoogroup s.com [mailto:ekg_club@yahoogroup s.com] On Behalf Of Klaus Skrudland
                Sent: Friday, January 30, 2009 19:29
                To: ekg_club@yahoogroup s.com
                Subject: [ekg_club] postextrasystolic pause
                 
                Just an academic question here about the postextrasystolic pause with premature beats. I'm hoping someone can help.

                I've got a strip showing atrial bigeminy, and although PACs usually reset the SA Node and therefore present with noncompensatory pauses, I'd like to prove this. In atrial bigeminy, there is no normal sinus interval, as each sinus beat is followed by a PAC.

                My question is therefore: Can the postextrasystolic pause be determined in a bigeminal rhythm?


                To explain this a bit more thorough:

                To establish whether a postextrasystolic pause is compensatory or noncompensatory, one needs to look at the length of the normal interval and compare it to the added length of the coupling interval and the postextrasystolic pause.

                Compensatory pause: Coupling interval length + postex. pause length = 2 x normal interval (sinus cycle length)
                Noncompensatory pause: Coupling interval length + postex. pause length < 2 x normal interval (sinus cycle length)

                In a bigeminal rhythm, there is no normal interval, so how can I determine whether the pauses are compensatory or not?

                Anyone who can help?


                - klaus



                 


                From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.



                --
                Mvh,
                Klaus Nilsen Skrudland

                http://www.sykeplei eforum.no
                http://www.lapsklau s.com
                http://ecgblog. wordpress. com
                 + 47 99 38 67 55 


                From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.



                --
                Mvh,
                Klaus Nilsen Skrudland

                http://www.sykeplei eforum.no
                http://www.lapsklau s.com
                http://ecgblog. wordpress. com
                 + 47 99 38 67 55 
                 
                 


                From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.



                --
                Mvh,
                Klaus Nilsen Skrudland

                http://www.sykeplei eforum.no
                http://www.lapsklau s.com
                http://ecgblog. wordpress. com
                 + 47 99 38 67 55 




                --
                Mvh,
                Klaus Nilsen Skrudland

                http://www.sykeplei eforum.no
                http://www.lapsklau s.com
                http://ecgblog. wordpress. com
                 + 47 99 38 67 55 


                From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.

              • Robert Vroman
                I agree that at times 50 mm/s can be beneficial, especially in fast narrow rhythms and when looking for other nuances. When using the LP11 there was the option
                Message 7 of 17 , Feb 1, 2009
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                  I agree that at times 50 mm/s can be beneficial, especially in fast narrow rhythms and when looking for other nuances. When using the LP11 there was the option to change the speed to 50 mm/s which was great. On the LP12 the only option other than 25 mm/s is 12.5 mm/s (at least on ours). I have not figured out the reason for this as it “squishes” everything together. Spreading it out had much more benefit in my opinion.

                   

                  Robert

                   


                  From: ekg_club@yahoogroups.com [mailto: ekg_club@yahoogroups.com ] On Behalf Of Klaus Skrudland
                  Sent: Sunday, February 01, 2009 6:02 AM
                  To: ekg_club@yahoogroups.com
                  Subject: Re: [ekg_club] postextrasystolic pause

                   

                  Niklah - 

                  I'm not sure what you mean when you refer to unreliable P wave detection... ? The problem here was just that the bigeminy concealed the base rate/normal interval. I agree, you can't claim a pause to be compensatory nor noncompensatory unless you know the normal intervals. That is established also through the formula that Paul mentioned. 

                   

                  And when it comes to paper speed.. I'm sorry if I confuse you. I'd wish the opposite..! I live in Norway , and here there standard 12 lead paper speed is 50 mm/s. I do not know why. Or to put it another way, I can't undetstand why you guys would want to use 25mm/s. When running 50mm/s, it is much easier to spot P waves, to measure intervals and to look for those tiny little things that often tip the diagnosis in the right direction.. 

                   

                  :-)

                   

                  klaus

                   

                  On Sun, Feb 1, 2009 at 4:59 AM, Nikiah Nudell <medicnick@gmail. com> wrote:

                  Klaus - I have seen this same pattern a number of times as well in EGMs where you do not have reliable Pwave detection. Its tricky... and we've written about them before.

                   

                  I don't think you can claim it to be "compensatory" unless you actually know the basal intervals.

                   

                  Also, I think you are messing with our minds with 50mm/s strips. Is there any particular reason why you use this speed?

                   

                  Thanks,

                  Nick

                  On Sat, Jan 31, 2009 at 18:00, Klaus Skrudland <lapsklaus@gmail. com> wrote:

                  Paul - 

                   

                  It's a pleasure discussing these matters with someone with as much insight on the issue as you. You're perfectly right, the problem is that there is no normal interval or no base rate. And you're correct, this is exactly what I have been banging my head against the wall over. 

                   

                  For now, I've run out of clues on this one.. and as you say, the formula unfortunately cannon be used towards solving for X..  There might be other mathematical relationships between the coupling interval and the pause that could reveal eventual atrial reset, but that is unknown to me.. 

                   

                  Anyway, such discussions as this is very fun anyhow.. My brain got kick started too, thanks for participating. .! I'll let you (and the rest of the world) know if I come across anything on this..

                   

                  The ECG that this problem is derived from is by the way presented in my blog right here: 

                   

                   As you can see, I am trying to establish the ectopic origin of the premature contractions, using different approaches. And when I wanted to look at the postextrasystolic pause and apply the formula mentioned... I couldn't..! :-)

                   

                  Thanks! Klaus

                   

                  On Sat, Jan 31, 2009 at 11:24 PM, <PMATERAMD@aol. com> wrote:

                  hi again klaus,

                  basically you want to know if we can determine on an ecg wether or not an ecg showing atrial bigeminy reveals a compensatory pause(ie atrial reset) or non-compensatory pause(ie no atrial reset),

                  hmmmm ,  .., that's a good one,

                   

                  because there is no "normal" interval or known nsr rate, ... that complicates the issue, i would think that on surface ecgs there is not enough "data", ie, we dont have the base rate (so we cant interpolate the N_int) and/or base normal interval (N_int) , ..., as you know mathematically we usually would only need 2 of the 3 components of the formula to calculate the third but we are not solving for X, we are performing a relational equation to determine if the left side is = to right or if left side is > than right, ... i will need to roll this one around for a while more, let me know if you come across a viable answer / theory,

                  great question, gets the old neurons kick started, thanks,

                  Paul

                  Paul Matera, MD, FAEP, FAAIM, EMTP
                  Clinical Medicine, Emergency Services, Clinical Electrocardiography , Medical Education
                  Director Emeritus - Critical Care Units/Emergency Medicine, Providence Hospital , DC
                  Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR Team
                  Clinical Associate Professor - Medicine and Health Care Science, GWU , DC

                   

                  In a message dated 1/31/2009 1:36:05 P.M. Eastern Standard Time, lapsklaus@gmail. com writes:

                  Thanks a lot, Paul. I appreciate your help, but I'm already familiar with that formula. I've written about it and demonstrated it often in my blog (ecgblog.wordpress. com). I'm glad you mention it though, because I've been trying to apply this formula on an EKG that I have, and I can't figure out which interval to use as N_int. The strip shows an atrial bigeminal rhythm, and actually only shows coupling intervals and postextrasystolic pauses. 

                   

                   

                  Any ideas?

                   

                   

                   

                  With PACs the pause is normally noncompensatory. 

                  On Sat, Jan 31, 2009 at 6:50 PM, <PMATERAMD@aol. com> wrote:

                  if you just want a simple format to calculate odds of compensatory v non-compensatory you can use the formulas below that help give you the answer, my prior comments were directed so we can all think through what is happening and why

                  C_int + P_ex > 2 x N_int = Non-compensatory, pause is longer than the normal interval however not long enough for the coupling interval and the compensatory pause to be 2X the length of the normal interval 

                  C_int + P_ex = 2 x N_int = Compensatory, pause is long and the distance between the two normal beats is twice as long the normal interval in the underlying rhythm

                   

                  where:

                   

                  Coupling interval = C_int = The interval PP or RR between a normal sinus beat and premature beat

                   

                  Postextrasystole pause = P_ex = The following pause after a premature beat

                   

                  Normal interval = N_int = The interval , PP or RR

                   

                  hope this helps some

                   

                  Paul

                   

                   

                  Paul Matera, MD

                   

                   

                  In a message dated 1/31/2009 11:20:25 A.M. Eastern Standard Time, lapsklaus@gmail. com writes:

                  Paul - 

                  I do know the Ashman Phenomenon and the underlying mechamisms you describe, but this doesn't help me answer my initial question. Ashman beats usually occur during afib, due to changes in refractory times, and the aberrantly conducted complexes are usually seen after a long-short cycle. The criteria for Ashman Phenomenon were well described by Charles Fisch, and are called the Fisch Criteria if I remember correctly.

                   

                  Anyhow, my question was how one can differentiate between compensatory and noncompensatory extrasystolic pauses in a bigeminal pattern during sinus rhythm, since there is no "normal" PP interval to measure by. 

                   

                  I agree that it is essential to understand cellular physiology, etc. I like to think that I understand these things very well, but still I can't quite figure out the above. You seem to be skilled at this field, can you help me with an answer? :-)

                   

                   

                  On Sat, Jan 31, 2009 at 4:29 PM, <PMATERAMD@aol. com> wrote:

                  now we can muddy the waters a little more, ashman's phenomenon is similar to what you are discussing ....knowing how and why this occurs, especially since this phenom occurs after a "normal" beat has already occurred, all this goes back to one of my recent prior posts, i urge all colleagues here that do not fully understand cellular physiology, ie, resting potential, refractory period, excitability, automaticity, all based on sodium in, potassium out, electron charging, all controlled by calcium channels/02/ pH, ..., as i said if you understand these issue, understanding the outcome, ie the ecg, is easier,

                  stay safe,

                  Paul

                  Paul Matera, MD, FAEP, FAAIM, EMTP
                  Clinical Medicine, Emergency Services, Clinical Electrocardiography , Medical Education
                  Director Emeritus - Critical Care Units/Emergency Medicine, Providence Hospital , DC
                  Medical Director/Reserve Officer - Maryland State Police, MNRP/STAR Team
                  Clinical Associate Professor - Medicine and Health Care Science, GWU , DC

                   

                  In a message dated 1/30/2009 8:45:34 P.M. Eastern Standard Time, lapsklaus@gmail. com writes:

                  Niklah -

                  I have understood that:
                  A compensatory postextrasystolic pause occurs when a premature impulse spreads without depolarizing the atria, and thereby without resetting the SA Node. With a PVC, the early depolarization is normally isolated within the ventricular conduction tissue and therefore the SA Node is oblivious to the occured event and will continue pacing in a timely fashion. By definition, AV dissociation is present at the time the PVC occurs, and therefore the next sinus beat will appear precicely on time. On a surface EKG the coupling interval + the pause will be twice the length of the normal sinus interval.

                  Although, a PVC can produce a non-compensatory pause by resetting the SA node via retrograde (VA) conduction to the atria. In comparison, a PAC will normally activate the whole atria including the SA Node, and sinoatrial pacing will therefore be reset. Until the SA Node generates a new impulse, there will be a pause. This pause is not a multiple of the normal interval, and is called non-compensatory when seen on a surface EKG.

                  klaus

                  On Sat, Jan 31, 2009 at 2:31 AM, Nikiah Nudell <medicnick@gmail. com> wrote:

                  Klaus what is your physiologic definition of a compensatory pause?

                   

                  From: ekg_club@yahoogroup s.com [mailto:ekg_club@yahoogroup s.com] On Behalf Of Klaus Skrudland
                  Sent: Friday, January 30, 2009 19:29
                  To: ekg_club@yahoogroup s.com
                  Subject: [ekg_club] postextrasystolic pause

                   

                  Just an academic question here about the postextrasystolic pause with premature beats. I'm hoping someone can help.

                  I've got a strip showing atrial bigeminy, and although PACs usually reset the SA Node and therefore present with noncompensatory pauses, I'd like to prove this. In atrial bigeminy, there is no normal sinus interval, as each sinus beat is followed by a PAC.

                  My question is therefore: Can the postextrasystolic pause be determined in a bigeminal rhythm?


                  To explain this a bit more thorough:

                  To establish whether a postextrasystolic pause is compensatory or noncompensatory, one needs to look at the length of the normal interval and compare it to the added length of the coupling interval and the postextrasystolic pause.

                  Compensatory pause: Coupling interval length + postex. pause length = 2 x normal interval (sinus cycle length)
                  Noncompensatory pause: Coupling interval length + postex. pause length < 2 x normal interval (sinus cycle length)

                  In a bigeminal rhythm, there is no normal interval, so how can I determine whether the pauses are compensatory or not?

                  Anyone who can help?


                  - klaus



                   

                   


                  From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.




                  --
                  Mvh,
                  Klaus Nilsen Skrudland

                  http://www.sykeplei eforum.no
                  http://www.lapsklau s.com
                  http://ecgblog. wordpress. com
                  + 47 99 38 67 55

                   


                  From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.




                  --
                  Mvh,
                  Klaus Nilsen Skrudland

                  http://www.sykeplei eforum.no
                  http://www.lapsklau s.com
                  http://ecgblog. wordpress. com
                  + 47 99 38 67 55

                   

                   

                   


                  From Wall Street to Main Street and everywhere in between, stay up-to-date with the latest news.




                  --
                  Mvh,
                  Klaus Nilsen Skrudland

                  http://www.sykeplei eforum.no
                  http://www.lapsklau s.com
                  http://ecgblog. wordpress. com
                  + 47 99 38 67 55

                   




                  --
                  Mvh,
                  Klaus Nilsen Skrudland

                  http://www.sykeplei eforum.no
                  http://www.lapsklau s.com
                  http://ecgblog. wordpress. com
                  + 47 99 38 67 55

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