Okay, here is what I know and keep in mind this is human pathology:
HCM is a genetic condition. It means there is too much (hyper) muscle (troph) in the heart. This extra muscle leaves less room for blood to adequately flow, depending on how much extra muscle is there. Scarring also happens, which can alter the electrical pathways in the heart. The condition becomes unsafe when the muscle affects the blood flowing out of the heart. This can take years to happen, or it can be very fast. This is why you hear about sudden cardiac arrest, the heart just is no longer able to pump. In my heart, there is thickening in the septum (the muscle that divides the two sides of the heart). The typical presentation is that the septum is thickened near the top, which is where the aorta (the vessel that supplies blood to your body) is located. This thickening would eventually cut off flow through the aorta. In my case, the septum is thickened near the middle, which is dangerous for the electrical activity. I am instructed not to bring my pulse above 140, or lift over 40lbs, for fear of a dangerous rhythm occurring. I'm still early on in the pathology, but eventually I will probably need a implanted cardio defibrillator (a device that will shock my heart back into a safe rhythm if necessary). There is a radical open heart surgery that can be performed called a myectomy, in which they essentially shave down the extra muscle. It will grow back eventually though. I imagine this is why the prognosis in cats is what it is, because the science hasn't caught up to little kitty hearts yet. I wish there were all these options for animals too!
I myself almost never feel any pain, just maybe a little twinge here or there. I do get out of breath quicker than your average 20 something though.
HCM is a genetic condition. It means there is too much (hyper) muscle (troph) in the heart. This extra muscle leaves less room for blood to adequately flow, depending on how much extra muscle is there. Scarring also happens, which can alter the electrical pathways in the heart. The condition becomes unsafe when the muscle affects the blood flowing out of the heart. This can take years to happen, or it can be very fast. This is why you hear about sudden cardiac arrest, the heart just is no longer able to pump. In my heart, there is thickening in the septum (the muscle that divides the two sides of the heart). The typical presentation is that the septum is thickened near the top, which is where the aorta (the vessel that supplies blood to your body) is located. This thickening would eventually cut off flow through the aorta. In my case, the septum is thickened near the middle, which is dangerous for the electrical activity. I am instructed not to bring my pulse above 140, or lift over 40lbs, for fear of a dangerous rhythm occurring. I'm still early on in the pathology, but eventually I will probably need a implanted cardio defibrillator (a device that will shock my heart back into a safe rhythm if necessary). There is a radical open heart surgery that can be performed called a myectomy, in which they essentially shave down the extra muscle. It will grow back eventually though. I imagine this is why the prognosis in cats is what it is, because the science hasn't caught up to little kitty hearts yet. I wish there were all these options for animals too!
I myself almost never feel any pain, just maybe a little twinge here or there. I do get out of breath quicker than your average 20 something though.
