Relation of hemodynamic load to left ventricular hypertrophy and performance in hypertension

Abstract

Left ventricular hypertrophy and dysfunction in patients with hypertension are often poorly related to the level of blood pressure. To evaluate the reasons for this, 100 untreated patients (44 .+-. 14 yr) with essential hypertension were studied using cuff blood pressure and quantitative echocardiography to measure left ventricular mass index and end-diastolic relative wall thickness as 2 indexes of left ventricular hypertrophy. Left ventricular hypertrophy, as measured by either left ventricular mass index or end-diastolic relative wall thickness, correlated weakly with all indexes of blood pressure including systolic, diastolic and mean blood pressure (r = 0.16-0.32). End-diastolic relative wall thickness, an index which assesses the severity of concentric hypertrophy, showed a closer direct relation with total peripheral resistance (r = 0.52, P < 0.001) and a significant inverse relation with cardiac index (r = -0.47, P < 0.001). Left ventricular performance as assessed by fractional systolic shortening of left ventricular internal dimensions was not significantly related to left ventricular mass index, blood pressure or peak systolic wall stress, but declined significantly with increasing mean systolic wall stress (r = -0.42, P < 0.001) and even more with increasing end-systolic wall stress (r = -0.71, P < 0.001). Apparently, in patients with hypertension, left ventricular hypertrophy is correlated only modestly with measurements of resting blood pressure; and the classic pattern of concentric left ventricular hypertrophy, as measured by relative wall thickness, is more closely related to the typical hypertensive abnormality of elevated peripheral resistance, suggesting these anatomic and hemodynamic changes may be pathophysiologically interdependent. Left ventricular performance declines when the pressure overload in hypertension is not offset by compensating hypertrophy, allowing wall stresses to increase.