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Re: [echocardiography] Continuity

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  • nnaneko@aol.com
    We routinely use the continuity equation for prosthetic valves. We use the LVOT measurement for the equation. Nanci McFarland, RDCS Kaiser, Walnut Creek, CA
    Message 1 of 11 , Sep 30 8:53 PM
      We routinely use the continuity equation for prosthetic valves. We use the
      LVOT measurement for the equation.
      Nanci McFarland, RDCS
      Kaiser, Walnut Creek, CA
    • Paolo Barbier
      I do routinely, and use LVOT internal diameter immediately below valve as in aortic stenosis. I personally think routine use of continuity equation (in all
      Message 2 of 11 , Oct 1, 2001
        I do routinely, and use LVOT internal diameter immediately below valve as
        in aortic stenosis. I personally think routine use of continuity equation
        (in all aortic prosthesis and valve stenoses) is a good way to increase
        personal reproducibility of the method. I perform when possbile valve
        planimetry to compare with the equation. This has imporved over time my
        confidence in the measurement, which has demostrated to be reliable (used
        together with clinical judgement and all the other indirecty echo signs) in
        many difficult situations.

        P. Barbier

        At 15.42 29/09/01 +0100, you wrote:
        > A question for the group, When assessing Ao Valve replacement does
        >anyone use the continuity equation routinely ? If you do ,do you measure
        >LVOT or use the internal diameter of the replacement valve ring ? Thank
        >-you Jane.
        > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
        Dr. Paolo Barbier, MD
        Centro Cardiologico Fondazione Monzino, IRCCS
        20138 Milano, Italy
        Tel: +39 02 58002567 - Fax: +39 02 504667
        email: pbar@... - website: http://www.echobyweb.com
      • Philippe Pibarot
        We routinely use the continuity equation with the LVOT diameter directly measured by 2D echo to estimate the effective orifice area (EOA) of aortic prosthetic
        Message 3 of 11 , Oct 1, 2001
          We routinely use the continuity equation with the LVOT diameter directly measured by 2D echo to estimate the effective orifice area (EOA) of aortic prosthetic valves. A few years ago, we have done a study (reference below) showing that prosthesis size should not be used instead of LVOT diameter during calculation of prosthetic valve EOA. Indeed, the calculation with prosthesis size overtesimated the reference valve EOA (in vitro EOA) by 15+-23 %. In this context, it should be mentioned that there are often important discrepancies between the labeled valve size and the actual outer ring diameter of the prosthesis. Also, surgeons often insert the prosthesis in a supra-annular position in order to insert a larger prosthesis.

          Philippe.

          Reference:
          Pibarot P, Honos GN, Durand LG, Dumesnil JG. Substitution of left ventricular outflow tract diameter with prosthesis size is inadequate for calculation of aortic prosthetic valve area by the continuity equation. J Am Soc Echocardiogr, 1995,8:511-517.

          Jane and Paul Graham wrote:

          A question for the group, When assessing Ao Valve replacement does anyone use the continuity equation routinely ? If you do ,do you measure LVOT or use the internal diameter of the replacement valve ring ? Thank -you Jane.


          Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

          --
          Philippe Pibarot, DVM, PhD, FACC
          Assistant professor, Department of Medicine, Laval University
          Quebec Heart Institute, Laval Hospital
          2725 Chemin Sainte Foy,
          Sainte Foy, G1V-4G5, Quebec, Canada
          Phone: 418-656-8711 Ext 5938   Fax: 418-656-4509
           

        • GersonSL@aol.com
          This is a debate I have had with my director on more than one occasion. If you look at the principle of the continuity equation, one should always use the
          Message 4 of 11 , Oct 1, 2001
            This is a debate I have had with my director on more than one occasion. If
            you look at the principle of the continuity equation, one should always use
            the diameter at the place where you obtain your pulsed wave sample.
            Unfortunately, in many instances the actual pulse sample is not clearly
            defined and the LVOT tract is not round (as required in the "pi r squared"
            portion of the formula). So while I do use the formula, I consider it useful
            for following the same patient more than making an absolute evaluation on the
            first visit.

            And that brings us back to the value of a baseline echocardiogram shortly
            after surgery!

            Gerson S. Lichtenberg, RDCS, APS
            Cardiology Department
            Oak Park Hospital
            Oak Park, Illinois

            In a message dated 9/30/2001 7:38:38 PM, jpg132@... writes:

            << A question for the group,


            When assessing Ao Valve replacement does anyone use the continuity equation
            routinely ? If you do ,do you measure LVOT or use the internal diameter of
            the replacement valve ring ?


            Thank -you


            Jane. >>
          • Mark Harry
            The dimensionless LVOT / AV VTI ratio is a very usefull tool for assessing the systolic performence of any aortic valve. Mark Harry Iowa Heart Center
            Message 5 of 11 , Oct 2, 2001
              The dimensionless LVOT / AV VTI ratio is a very usefull tool for assessing
              the systolic performence of any aortic valve.

              Mark Harry
              Iowa Heart Center

              > ----------
              > From: GersonSL@...
              > Reply To: echocardiography@yahoogroups.com
              > Sent: Monday, October 1, 2001 6:21 PM
              > To: echocardiography@yahoogroups.com
              > Subject: Re: [echocardiography] Continuity
              >
              > This is a debate I have had with my director on more than one occasion. If
              >
              > you look at the principle of the continuity equation, one should always
              > use
              > the diameter at the place where you obtain your pulsed wave sample.
              > Unfortunately, in many instances the actual pulse sample is not clearly
              > defined and the LVOT tract is not round (as required in the "pi r squared"
              >
              > portion of the formula). So while I do use the formula, I consider it
              > useful
              > for following the same patient more than making an absolute evaluation on
              > the
              > first visit.
              >
              > And that brings us back to the value of a baseline echocardiogram shortly
              > after surgery!
              >
              > Gerson S. Lichtenberg, RDCS, APS
              > Cardiology Department
              > Oak Park Hospital
              > Oak Park, Illinois
              >
              > In a message dated 9/30/2001 7:38:38 PM, jpg132@... writes:
              >
              > << A question for the group,
              >
              >
              > When assessing Ao Valve replacement does anyone use the continuity
              > equation
              > routinely ? If you do ,do you measure LVOT or use the internal diameter of
              >
              > the replacement valve ring ?
              >
              >
              > Thank -you
              >
              >
              > Jane. >>
              >
              >
              >
              >
              > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
              >
              >
            • Martin Giles
              It has been suggested that the outflow tract diameter does not change dramatically over time and that as the greatest potential error in the calculation of
              Message 6 of 11 , Oct 2, 2001
                It has been suggested that the outflow tract diameter does not change dramatically over time and that as the greatest potential error in the calculation of valve area is found in this variable we should use a baseline diameter for all subsequent calculations. Does the group have any views on this!
                 
                Martin Giles
                Nottingham
                UK 
                 
                ----- Original Message -----
                Sent: Saturday, September 29, 2001 3:42 PM
                Subject: [echocardiography] Continuity

                A question for the group,
                 
                When assessing Ao Valve replacement does anyone use the continuity equation routinely ? If you do ,do you measure LVOT or use the internal diameter of the replacement valve ring ?
                 
                Thank -you
                 
                Jane.

                Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
              • Mark Harry
                Martin, That assumes that the first measurement was done correctly. We employ 16 sonographers. Some are more skilled than others. I rarely look at the
                Message 7 of 11 , Oct 2, 2001
                  Martin,

                  That assumes that the first measurement was done correctly. We employ 16
                  sonographers. Some are more skilled than others. I rarely look at the
                  previous data until after I have completed my exam. If there is a
                  significant difference I review the original data and attempt to determine
                  why there is a difference and which measurement should be used.

                  Mark Harry
                  Iowa Heart Center


                  > ----------
                  > From: Martin Giles
                  > Reply To: echocardiography@yahoogroups.com
                  > Sent: Tuesday, October 2, 2001 2:01 PM
                  > To: echocardiography@yahoogroups.com
                  > Subject: Re: [echocardiography] Continuity
                  >
                  > It has been suggested that the outflow tract diameter does not change
                  > dramatically over time and that as the greatest potential error in the
                  > calculation of valve area is found in this variable we should use a
                  > baseline diameter for all subsequent calculations. Does the group have any
                  > views on this!
                  >
                  > Martin Giles
                  > Nottingham
                  > UK
                  >
                  > ----- Original Message -----
                  >
                  > From: Jane and Paul Graham
                  > To: echocardiography@yahoogroups.com
                  > Sent: Saturday, September 29, 2001 3:42 PM
                  > Subject: [echocardiography] Continuity
                  >
                  > A question for the group,
                  >
                  > When assessing Ao Valve replacement does anyone use the continuity
                  > equation routinely ? If you do ,do you measure LVOT or use the internal
                  > diameter of the replacement valve ring ?
                  >
                  > Thank -you
                  >
                  > Jane.
                  >
                  > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
                  >
                  >
                  >
                  >
                  > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
                  >
                • Mark Harry
                  When a patient has normal LV function (EF greater than or equal to 55%), we assume a normal cardiac index of 3.0 L/min/M2. We then estimate this patient s
                  Message 8 of 11 , Oct 2, 2001
                    When a patient has normal LV function (EF greater than or equal to 55%), we
                    assume a normal cardiac index of 3.0 L/min/M2. We then estimate this
                    patient's stroke volume by multiplying 3.0 (normal cardiac index) times the
                    patient's body surface area. This gives us the patient's cardiac output.
                    We then multiply the cardiac output by 1000. This gives us an estimated
                    cardiac output in ml/min. Divide the cardiac output by the patient's heart
                    rate. This gives us an estimate of the patient's stroke volume. Dividing
                    this stroke volume by the aortic valve VTI obtained by CW Doppler will give
                    us an estimate of the patient's aortic valve area. Our digital echo
                    reporting package does this automaticlly and we compare this simplified
                    aortic valve area with the Continuity valve area. This has been very
                    helpful when the LVOT diameter and/or VTI data is of questionable quality.

                    (BSA x 3000) ÷ HR = SV SV ÷ AV VTI = AVA

                    Mark Harry
                    Iowa Heart Center

                    > ----------
                    > From: GersonSL@...
                    > Reply To: echocardiography@yahoogroups.com
                    > Sent: Monday, October 1, 2001 6:21 PM
                    > To: echocardiography@yahoogroups.com
                    > Subject: Re: [echocardiography] Continuity
                    >
                    > This is a debate I have had with my director on more than one occasion. If
                    >
                    > you look at the principle of the continuity equation, one should always
                    > use
                    > the diameter at the place where you obtain your pulsed wave sample.
                    > Unfortunately, in many instances the actual pulse sample is not clearly
                    > defined and the LVOT tract is not round (as required in the "pi r squared"
                    >
                    > portion of the formula). So while I do use the formula, I consider it
                    > useful
                    > for following the same patient more than making an absolute evaluation on
                    > the
                    > first visit.
                    >
                    > And that brings us back to the value of a baseline echocardiogram shortly
                    > after surgery!
                    >
                    > Gerson S. Lichtenberg, RDCS, APS
                    > Cardiology Department
                    > Oak Park Hospital
                    > Oak Park, Illinois
                    >
                    > In a message dated 9/30/2001 7:38:38 PM, jpg132@... writes:
                    >
                    > << A question for the group,
                    >
                    >
                    > When assessing Ao Valve replacement does anyone use the continuity
                    > equation
                    > routinely ? If you do ,do you measure LVOT or use the internal diameter of
                    >
                    > the replacement valve ring ?
                    >
                    >
                    > Thank -you
                    >
                    >
                    > Jane. >>
                    >
                    >
                    >
                    >
                    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                    >
                    >
                  • MARTIN, DAVID S. (JSC-SD) (WLS)
                    We have done numerous longitudinal studies (measuring cardiac output among other things) in a relatively normal population. We use the first LVOT measurement
                    Message 9 of 11 , Oct 2, 2001
                      We have done numerous longitudinal studies (measuring cardiac output among other things) in a relatively normal population.  We use the first LVOT measurement throughout for that very reason.  Although that is a somewhat different situation than a patient whose clinical condition may be changing.

                      David S. Martin BBA, RDMS, RDCS, RVT
                      Ultrasound Lead
                      Cardiovascular Laboratory
                      NASA Johnson Space Center
                      Wyle Laboratories
                      281-483-9462
                      dsmartin@...

                      -----Original Message-----
                      [MARTIN, DAVID S. (JSC-SD)]  
                      From: Martin Giles [mailto:martin_giles@...]
                      Sent: Tuesday, October 02, 2001 2:02 PM
                      To: echocardiography@yahoogroups.com
                      Subject: Re: [echocardiography] Continuity

                      It has been suggested that the outflow tract diameter does not change dramatically over time and that as the greatest potential error in the calculation of valve area is found in this variable we should use a baseline diameter for all subsequent calculations. Does the group have any views on this!
                       
                      Martin Giles
                      Nottingham
                      UK 
                       
                      ----- Original Message -----
                      Sent: Saturday, September 29, 2001 3:42 PM
                      Subject: [echocardiography] Continuity

                      A question for the group,
                       
                      When assessing Ao Valve replacement does anyone use the continuity equation routinely ? If you do ,do you measure LVOT or use the internal diameter of the replacement valve ring ?
                       
                      Thank -you
                       
                      Jane.

                      Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

                      Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
                    • Martin Giles
                      As regulars to this forum will know there are often considerable differences in the way various international echo communities use and present echo data! I
                      Message 10 of 11 , Oct 3, 2001
                        As regulars to this forum will know there are often considerable differences
                        in the way various international echo communities use and present echo data!
                        I also find the dimensionless ratio useful but the resulting number is an
                        "echo number" and as such is not always understood by the wider clinical
                        community who are much happier with concepts that they can understand, e.g.
                        gradients and valve area. Is this a problem elsewhere?

                        Martin Giles
                        UK

                        ----- Original Message -----
                        From: "Mark Harry" <mharry@...>
                        To: <echocardiography@yahoogroups.com>
                        Sent: Tuesday, October 02, 2001 5:35 PM
                        Subject: RE: [echocardiography] Continuity


                        > The dimensionless LVOT / AV VTI ratio is a very usefull tool for assessing
                        > the systolic performence of any aortic valve.
                        >
                        > Mark Harry
                        > Iowa Heart Center
                        >
                        > > ----------
                        > > From: GersonSL@...
                        > > Reply To: echocardiography@yahoogroups.com
                        > > Sent: Monday, October 1, 2001 6:21 PM
                        > > To: echocardiography@yahoogroups.com
                        > > Subject: Re: [echocardiography] Continuity
                        > >
                        > > This is a debate I have had with my director on more than one occasion.
                        If
                        > >
                        > > you look at the principle of the continuity equation, one should always
                        > > use
                        > > the diameter at the place where you obtain your pulsed wave sample.
                        > > Unfortunately, in many instances the actual pulse sample is not clearly
                        > > defined and the LVOT tract is not round (as required in the "pi r
                        squared"
                        > >
                        > > portion of the formula). So while I do use the formula, I consider it
                        > > useful
                        > > for following the same patient more than making an absolute evaluation
                        on
                        > > the
                        > > first visit.
                        > >
                        > > And that brings us back to the value of a baseline echocardiogram
                        shortly
                        > > after surgery!
                        > >
                        > > Gerson S. Lichtenberg, RDCS, APS
                        > > Cardiology Department
                        > > Oak Park Hospital
                        > > Oak Park, Illinois
                        > >
                        > > In a message dated 9/30/2001 7:38:38 PM, jpg132@... writes:
                        > >
                        > > << A question for the group,
                        > >
                        > >
                        > > When assessing Ao Valve replacement does anyone use the continuity
                        > > equation
                        > > routinely ? If you do ,do you measure LVOT or use the internal diameter
                        of
                        > >
                        > > the replacement valve ring ?
                        > >
                        > >
                        > > Thank -you
                        > >
                        > >
                        > > Jane. >>
                        > >
                        > >
                        > >
                        > >
                        > > Your use of Yahoo! Groups is subject to
                        http://docs.yahoo.com/info/terms/
                        > >
                        > >
                        >
                        >
                        >
                        > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                        >
                        >
                        >
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