Captopril and hypertensive cardiopathy : therapeutic effects and hormonal changes [Captopril e cardiopatia ipertensiva: effetti terapeutici e modificazioni ormonali]

The effect of a single oral dose (50 mg) of captopril was studied in 12 hypertensive patients divided into 2 groups: 6 had a normal hemodynamic profile; the other 6 had NYHA class III or IV heart failure. Medical history and clinical and laboratory investigation showed that the heart failure was due exclusively to arterial hypertension. Mean arterial pressure (MAP), aldosterone, plasma renin activity (PRA) and atrial natriuretic factor (ANF) were followed for 4 hours after administration of captopril. MAP values showed a similar decrease in the 2 groups but the variations in the 3 hormones were much greater in the second group. This group showed higher basal levels of PRA, aldosterone and ANF; after stimulation PRA increased sharply preceded by a substantial decrease in aldosterone and ANF. To explain this phenomenon, the Authors propose that the liver of the patients with heart failure is unable to rapidly compensate the reduction in synthesis of angiotensin II caused by the drug with a corresponding increase in angiotensinogen production; the consequent sharp drop in plasma aldosterone would lead to a rise in renin production by the kidney. The arteriolar and venous vasodilatation induced by the ACE-inhibitor, would explain the drop in intra-atrial pressure with reduced plasma levels of ANF. The decrease in ANF could also be caused by the inhibition of the renin-angiotensin system of the heart leading to improved blood supply and hence myocardial contractility.