I'm sorry to hear about your kitty, she sounds very sick.
Pulmonary embolus usually presents with dry lungs (ie no edema) and
a very fast heart rate with dyspnea. The presence of the pulmonary
edema has me leaning away from an embolus. The fact that her red
count keeps dropping after transfusions, especially combined with
the low potassium, which is involved in blood clotting, has me
wondering if she is bleeding somewhere. Have they done an abdominal
ultrasound and tested her stool for blood?
The clots for pulmonary embolus are formed in the body and travel to
the right side of the heart and lodge in the lungs. They can also
be formed in the right side of the heart due to arrthymias or
enlargement issues. Since most HCM kitties have mostly left sided
involvement, a pulmonary embolus is not a common complication of HCM.
The gallop rhythm might related to her anemia. If her red blood
cells are very low, they cannot always get enough oxygen to the
heart to fully oxygenate it, so areas can become "irritated" and
fire off before they should. If her blood pressure is low the same
thing can happen. Potassium is also essential to normal heart
rhythm, so her hypokalemia may also be a contributing factor. Her
dilated pupils were likely a response to the stress of not being
able to breathe - it is part of the fight or flight response.
These are just some ideas; I'm not a vet or MD just a paramedic, so
I deal with acutely life threatening situations, not the ongoing
illnesses. It sounds like she is getting the best of care by vets
who are able to observe her directly and have the whole picture.
Good luck, Ms P will be in our thoughts. Keep us updated.
jen, deagan and kira the dog