Summary:
Left ventricular mass and function were evaluated by M-mode echocardiography in 10 patients with essential hypertension, before and after 16 weeks of treatment with clonidine. Plasma renin activity (PRA), serum and 24-h urinary Na and K were also determined. The dose range of clonidine was 0.15-0.45 mg/day. Systolic and diastolic blood pressure decreased significantly since the second week of treatment (p < 0.0001). There was a decrease in calculated total peripheral resistance (35.3 ± 11.08 to 30.91 ± 6.6 RU p < 0.01), end meridional (72.9 ± 23.6 to 58.5 ± 22 dynes/cm2 x 103, p < 0.001) and peak systolic wall stress (453.5 ± 140 to 378 ± 97 dynes/cm2 x 103, p < 0.01), wall tension (333 ± 36 to 286.6 ± 42, p < 0.01). Left ventricular mass index decreased in six patients (83.7 ± 20.4 to 70.7 ± 12.4 g/m2,p < 0.001). Decreasein left ventricular mass index was related to decrease-in wall tension (r = 0.70 p < 0.01) and septal thickness in diastole (r = 0.71,p < 0.01). There was a decrease in “double product” (10,934 ± 1,975 to 8,705 ± 1,739, p < 0.01), PRA (3.74 ± 2.51 to 2.51 ± 1.44 ng/ml/h p<0.01) with increase in 24-h urinary Na (114.9 ± 37 to 155.3 ± 55.8 mEq/24-h urine, p < 0.001). Cardiac index, left ventricular ejection fraction and fractional shortening increased without significance (p = NS). It is concluded, therefore, that clonidine is an antihypertensive agent which reduces myocardial oxygen consumption factors, left ventricular mass index and PRA, improving contractility indexes, and increases Na excretion, probably by aldosterone blocking related effect. Decrease in diastolic septal wall thickness was considered as probably related to specific sympathetic inhibition.
Address correspondence and reprint requests to Dr. Jorge Velandia Arevalo at Cardiology Section, National Cancer Institute, Bogota, Colombia.
© Lippincott-Raven Publishers.
