Assessment of the systolic function and contractility of the hypertensive left ventricle

Abstract

Sustained hypertension is a stimulus for development of cardiac hypertrophy, which may be either concentric or eccentric. For a given rise of aortic pressure, left ventricle (LV) wall stress (afterload) may remain normal or reduced in the former and become enhanced in the latter condition, and the LV systolic function may vary in a direction opposite to that of wall stress. It is unknown whether there are also differences in contractile properties that may have a role in the shift from normal systolic function. To clarify this we evaluated the velocity of LV fiber shortening and the fractional fiber shortening in normotensive and hypertensive subjects with normal heart size (group 1), or concentric LV (group 2) or eccentric LV (group 3) hypertrophy during baseline and after an acute hemodynamic overload induced by a cold pressor test (CPT). We found that the functional pattern in the two conditions was similar to normal in group 1, significantly enhanced during baseline and CPT in group 2, and was depressed during baseline and more so during CPT in group 3. These findings suggest that the contractile properties of the two types of hypertrophy are different, supported by the slope of the force-length line defined by the end systolic stress-end systolic volume relation in the baseline and during the hemodynamic overload imposed by the CPT. This line was steeper than normal in group 2 and less steep than normal in group 3. It remains to be defined whether the two types of hypertrophy are a separate disorder or represent a different stage of the same disease.