Cardiac Hypertrophy and Altered Cellular Electrical Activity of the Myocardium

The electrophysiologic changes associated with this form of hypertrophy provoked by pressure overload are described and pertinent mechanical, structural, and biochemical data which are concomitant and may be related to the electrical changes are considered.

Abstract

The myocardial cell hypertrophies in response to a sustained increase in workload including pressure overload due to ventricular or systemic hypertension; volume overload because of an AV fistula, other defects in the heart pump, or hypervolemia; and sustained increase in heart rate. It can be subsequent to regional damage brought about by acute or chronic ischemia and infarction, by nutritional and hormonal disturbances, and by dynamic {1} and isometric exercise {2}. There are numerous changes concomitant with, and perhaps associated with, myocardial hypertrophy, including recently described electrophysiological alterations. Hypertrophy may be compensatory, allowing the heart to meet the increased workload; if hypertrophy is insufficient, pump failure ensues {3, 4}. This review is limited to an examination of changes occurring in a common well-studied form of hypertrophy, that provoked by pressure overload. We describe and emphasize the electrophysiologic changes associated with this form of hypertrophy and also consider pertinent mechanical, structural, and biochemical findings. We refer to other models and to naturally occurring disease-induced hypertrophy when relevant.