can anyone explain the physiological benefits of cardiac hypertrophy and remodeling as a compensatory mechanism in heart failure? Is it short term, to increase the preload therefore increasing cardiac output
Feb 29, '12
I don't think there are any real, long term benefits, but yes, I think you are right. The muscle gets weaker, so it grows larger to make up for the drop in efficiency. A healthy heart has an ejection fraction of 50 - 60%. One in end stage CHF will be in the 10% range and be barely able to keep you afloat. Then it's time for the LVAD, although they are pushing to put those in much earlier, before irreversible kidney damage and the like, occurs.
Mar 1, '12
One of the major causes of cardiac hypertrophy is increased afterload (e.g. hypertension, coarctatio of the aorta, aortic valve stenosis). Hypertrophy is only beneficial in early stages of heart failure as it counteracts the increased afterload.
As far as I'm aware hypertrophy isn't similar to increased preload. Because increased preload would imply greater initial stretch of the sarcomeres in the cardiomyocytes and that's not what happens in hypertrophy. The number of sarcomeres per cardiomyocyte get upregulated so the inotropic force of your heart would increase by this. As a result the afterload-to-sarcomere ratio is decreased and this makes the influence the afterload has on the heart as a unit less extensive. This in all leads to increased performance of the heart initially
Of course over time the hypertrophy causes problems in and by itself. Myocardial oxygen demand goes up and you can have all kinds of inflow and outfow obstructions by hypertrophy that would respectively decrease preload, increase afterload. And generally the cause of the hypertrophy hasn't resolved. Aortic valve stenosis leads to an even more narrow passage through the valve, hypertension persists etc. So the answer of the body is more and more hypertrophy until the system spins out of control.