Diastolic compliance of the left ventricle in man

Two coordinates of left ventricular end-diastolic pressure (P) and volume (V) were provided by the Infusion of anglotensin in 22 patients. The slope (k) of the in P-V relation, coupled with knowledge of the operating (end-diastolic) pressure allows determination of end-diastollc volume compliance (dV/VdP). Estimates of end-diastolic compliance from a single coordinate of pressure and volume compared well (r = 0.90) with the two coordinate method, whereas values for specific compliance (ΔV/V_i ΔP) appeared to be misleading in cases of idiopathic hypertrophic subaortic stenosis and congestive cardiomyopathy. Since volume compliance is determined in part by the operating pressure, compliance may be reduced in small, normal or enlarged ventricles. Left ventricular linear compliance was derived from volume compliance and was normalized for left ventricular wall thickness. The product of linear compliance and end-dlastolic stress provides an index of myocardial strain, termed "muscle fiber stretch," which may be related to systolic performance and thus allow comparison of length-performance relations in ventricles with normal and abnormal compliance.