Contractile and Relaxing Functions of the Left Ventricle and Its Responses to Nitroprusside in Hypertensive Hypertrophic Heart Disease

Jeong, Myung Ho; Cho, Jeong Gwan; Park, Jong Chun; Kang, Jung Chaee; Park, Ock Kyu

Abstract

Two factors of the ventricular function, systolic contractile and diastolic relaxing functions, cooporate in pumping the adequate blood volumes to suffice bodily demands. In some hypertensive patients with marked left ventricular hypertrophy, the intact systolic function of the ventricle associated with clinical symptom of congestive heart failure(CHF), which is considered to be a consequence of diastolic dysfunction. In this study 10 hypertensive patients(group A) complaining of exertional dyspnea or chest pain with increased left ventricular mass index and normal systolic function and 6 normotensive controls(group B) were examined by cardiac catheterization and echocardiography to assess the left ventricular systolic and diastolic function and ventricular responses to constant infusion of nitroprusside. Various systolic and diastolic function indices were measured by cardiac catheterization and echocardiography. 1) The ejection fraction(EF), fractional fiber shortening, mean velocity of circumferential fiber shortening, left ventricular(LV) peak+dp/dt, change of slope of LV peak systolic pressure-volume and pressure-dimension relations in group A were not different from those of group B in the resting states. 2) Diastolic dysfunction was evidenced by prolonged A2D time, decreased OR slope, decreased peak negative dp/dt and increased diastolic time constant 'T' in group A. 3) Cardiac index by thermodilution method was negatively related to left ventricular mass index(LVMI) measured by echocardiography, whereas time constant T was positively related to LVMI. 4) With constant infusion of nitroprusside, LV systolic pressure, LV end-diastolic pressure and pulmonary arterial pressure were decreased, and left ventricular end-systolic stress and stroke work index(SWI) derived from left ventricular pressure-volume loop area were decreased, EF was increased, but time constant T was prolonged and cardiac output(CO) by thermodilution method was decreased in group A. 5) In group B, with constant infusion of nitroprusside, EF, SWI and CO were pratically unaffected and time constant T was not prolonged significantly. These reults suggest that patients with hypertensive hypertrophic left ventricle is associated with diastolic dysfunction, which could further be exacerbated by a vasodilator such as nitroprusside.