[Effects of calcium antagonists or beta-blockade on left ventricular diastolic function in essential hypertension]

This study was performed to assess the effect of a calcium channel blocker (nifedipine) and beta-blockade (atenolol) on left ventricular early diastolic function and filling in essential hypertension (WHO stage I, II; HT). Twenty-two untreated patients were randomly divided as nifedipine (11 patients) and atenolol (11 patients) treatment groups and both the groups had complete echocardiographic and Doppler studies. Twenty normotensive cases served as controls. Clinical and echo-Doppler data obtained at baseline and four weeks after initiation of each therapy showed no difference between the two HT groups as to mean blood pressure (before therapy, 119 +/- 3 vs 117 +/- 11 mmHg; after therapy, 106 +/- 3 vs 110 +/- 3 mmHg), left ventricular dimension, left atrial dimension, and wall thickness. To evaluate early diastolic function, the interval from the aortic closure sound (IIA, phonocardiography) to the opening of the mitral valve (MVO, echocardiography) and that from MVO to the O point of the apexcardiogram were measured. The IIA-O interval was also calculated. The peak velocities in the rapid filling (R) and atrial contraction phases (A) were measured using pulsed Doppler echocardiography at the center of the mitral orifice. The MVO-O/IIA-MVO and A/R ratios were also calculated. Compared with the controls, the IIA-O interval (143.9 +/- 6.8 msec) and the IIA-MVO interval (81.5 +/- 4.9 msec) were significantly prolonged in HT (p less than 0.01). There was no significant difference between the MVO-O interval and R. Velocity A (54.2 +/- 2.7 cm/sec) and the A/R ratio (1.01 +/- 0.11) increased significantly in HT (p less than 0.05). The IIA-O interval (before therapy, 153.3 +/- 7.6 vs after therapy, 134.3 +/- 6.2 msec) and IIA-MVO interval (87.3 +/- 6.3 vs 77.8 +/- 5.9 msec) decreased and R (43.7 +/- 3.8 vs 49.1 +/- 3.0 cm/sec) increased significantly with nifedipine. The IIA-O interval (135.7 +/- 11.3 vs 150.4 +/- 7.6 msec) and the MVO-O (58.4 +/- 3.9 vs 66.5 +/- 4.7 msec) interval were significantly prolonged with atenolol, however the IIA-MVO interval, R, and A/R did not change. A (57.5 +/- 4.0 vs 50.2 +/- 2.9 cm/sec) was also significantly decreased with atenolol. There was a significant correlation between reduction in velocity A and prolongation in the MVO-O interval (r = -0.62, p less than 0.05) with atenolol. These results suggested that the prolongation of the diastolic closure rate of the mitral valve by atenolol was related to increased ventricular filling and decreased atrial contraction.(ABSTRACT TRUNCATED AT 400 WORDS)