ABSTRACT
Physiological hypertrophy is a normal part of the growth response of cells, including cardiomyocytes, which are terminally differentiated and cannot undergo hyperplastic growth. This form of hypertrophy is described as both concentric (characterized by addition of sarcomeres in parallel, leading to increased width of the myocyte) and eccentric (characterized by the addition of sarcomeres in series, leading to increased length). Concentric cardiac hypertrophy can also develop as a response to stressors, in most cases an excess load placed on the heart; for example, with uncorrected hypertension or valvular disease, or post-MI (myocardial infarction) when the remote noninfarcted myocardium hypertrophies. Hypertrophy is initially believed to be adaptive, normalizing systolic wall stress, though this concept has been challenged recently and it is not clear that hypertrophy is really necessary to maintain systolic function in the face of moderately elevated afterloads. Eccentric hypertrophy results most often from volume loads such as those seen with valvular insufficiency.
