Hemodynamics in the Juvenile Hypertension with Special Reference to the Response to Propranolol

Hemodynamic characteristics in 22 cases of juvenile hypertension were studied. Cardiac index in group 1 (blood pressure always exceeded 150/90mmHg) was 4.05±0.84 L/min/M2, while it increased significantly by 5.39±1.20 in group 2 (blood pressure oscillated around 150/90mmHg). The peripheral resistance was elevated in group 1, 2348±575 dyne sec cm-5/M2, and it remained within normal range, 1534 ±428, in group 2. The increase in cardiac index in group 2 was due to the increase in heart rate and stroke index. Blood volume revealed an inverse relationship to the resistance ; it increased significantly in normal resistance group. The correlation coefficient between peripheral resistance and mean blood pressure was 0.34, while resistance and cardiac index revealed close relationship (r=-0.84). Heart rate and stroke index were decreased after intravenous propranolol by 10.6 per cent and 13.5 per cent respectively, thereby decreasing the cardiac index by 21.6 per cent on the average. The correlation coefficients between the percent decrease after propranolol and control values of heart rate, stroke index and cardiac index were -0.52, -0.37, and -0.43 respectively. Blood pressure changed little, and resistance was increased by 29.9 per cent after propranolol. The results indicated the hyperactivity of the beta adrenergic system in juvenile labile hypertension.