AN ANALYSIS OF THE FACTORS CONCERNED IN THE AUTOMATIC ADJUSTMENT OF THE VENTRICLE TO INCREASED LOAD

Publisher Website
Google Scholar
Abstract
Studies on the isolated ventricle of the common sand turtle of 6-12 in. showed that the increase in diastolic vol. of the ventricle with increased arterial pressure depends upon the contraction rate, the filling pressure and the temp. The magnitude of [DELTA]V:[DELTA]P varies directly with the contraction rate, and inversely with the other 2 variables. Below a certain critical contraction rate and above a critical filling pressure the diastolic vol. is independent of the arterial pressure, within the ranges studied. This relation is to be expected because with low rates and high venous pressures the extent of diastolic filling is not so much influenced by the extent of systolic emptying as it is at higher rates and low filling pressures. The "law of the heart" with respect to the adaptation to increased pressure is not an expression of an intrinsic property of the cardiac muscle but depends upon the existence of proper extrinsic conditions regarding rate, temp. and filling pressure.