Effects of nifedipine on left ventricular systolic and diastolic functions in patients with left ventricular hypertrophy

The effect of nifedpine on left ventricular (LV) systolic and diastolic function was studied in 10 patients with hypertrophic cadiomyopathy(HCM), 8 patients with hypertensive hypertrophy(HT) and 9 normal subjects. Multigated cardiac blood pool imaging with Tc-99m were obtained at 40-degree left anterior oblique position before and after nifedipine administration (10 mg, sublingually). As systolic indices, we obtained LV ejection fraction and mean first third ejection rate. And as diastolic indices, mean filling rate during first third of diastole (1/3 FRsub(mean)) and diastolic maximal filling rate were calculated. Before nifedipine, systolic indices were significantly superior in HCM group than in other 2 groups, and diastolic indices were significantly lower in HCM and HT groups than in normal. After nifedipine, systolic indices improved in HT group but they did not change in other 2 groups. Diastolic indices improved significantly in HCM and HT groups after nifedpine. In HCM group, 1/3 FRsub(mean) improved more markedly in symptomatic patients than in asymptomatic patients. The ratio of diastolic function to systolic function (1/3 FRsub(mean)/1/3 ERsub(mean)) did not change in normal and HT groups but it increased significantly in HCM group. There we a slight increase in heart rate (HR) and decrease in systemic arterial pressure (BP). The increase in HR was similar among 3 groups but the decrease in BP was significantly greater in HT group in whom control BP was significantly higher than other groups. LV end-diastolic volume did not change in 3 groups by nifedipine administration. These data suggested that abnormal diastolic function in HCM and HT was faborably modified by nifedipine, but their mechanisms were different. In HT, it was considered to relate with improved systolic function due to LV afterload reduction, while in HCM, it was not related to the peripheral hemodynamic effects nor improved systolic function. (author)