The cardiac hypertrophic responses to pathologic and physiologic loads.

Myocardial hypertrophy is an adaptive response of the heart to an imposed load. Two distinct patterns of hypertrophy are discussed, pathologic and physiologic, which differ in their mechanical and biochemical features. Evidence is presented that supports the following hypotheses: the nature of the hypertrophy reflects the nature of the stimulus; the function of the hypertrophied heart reflects its biochemistry; and the degree of responsiveness of the heart varies with species and with age.