Left ventricular function in early primary hypertension. Functional consequences of cardiovascular structural changes.

An increase in left ventricular (LV) wall thickness will lead to decreased LV distensibility during both LV passive filling and left atrial contraction. Reduced LV distensibility will change the filling pattern of the left ventricle, and a proportionally smaller part of the stroke volume will be delivered during the passive filling of the preceding diastole and a larger part during late diastole by a more powerful left atrial contraction. With a more pronounced increase in LV wall thickness a reduced distensibility of venous capacitance vessels (functional or structural) will probably help to preserve LV pump function by influencing LV filling and use of the Frank-Starling mechanism. LV wall stress (peak and end-systolic) is high and LV intrinsic contractility is normal or supernormal in early primary hypertension, as judged from the relationship between end-systolic wall stress and different indices of LV function (fractional shortening, mean velocity of circumferential fiber shortening, ejection fraction). Great differences in peak systolic wall stress may be recorded among groups with comparable values for LV end-systolic wall stress, which may be explained by very different degrees of cardiovascular structural changes, with higher values for peak systolic wall stress seen in hypertension caused by high output than those values seen in hypertension caused by high total peripheral resistance. Signs of supernormal LV systolic function are common in high output hypertension, which is also at least partly due to an increase in LV end-diastolic volume and use of the Frank-Starling mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)