REGULATION OF PERIPHERAL VASCULAR TONE IN PATIENTS WITH HEART-FAILURE- CONTRIBUTION OF ANGIOTENSIN-II

Objective-To determine directly the contribution of angiotensin II to basal and sympathetically stimulated peripheral arteriolar tone in pat ients with heart failure. Design-Parallel group comparison. Subjects-N ine patients with New York Heart Association grade II-IV chronic heart failure, and age and sex matched controls. Interventions-Forearm plet hysmography, lower body negative pressure, local intra-arterial admini stration of losartan, angiotensin TI, and noradrenaline, and estimatio n of plasma hormone concentrations. Main outcome measures-Forearm bloo d flow responses, plasma hormone concentrations. Results-BaseLine bloo d pressure, heart rate, and forearm blood flow did not differ between patients and controls. In comparison with the non-infused forearm, los artan did not affect basal forearm blood flow (95% confidence interval -5.5% to +7.3%) or sympathetically stimulated vasoconstriction in con trols. However, the mean (SERI) blood flow in patients increased by 13 (5)% and 26(7)% in response to 30 and 90 mu g/min of losartan respecti vely (p < 0.001). Lower body negative pressure caused a reduction in f orearm blood flow of 20(5)% in controls (p = 0.008) and 13(5)% (p = 0. 08) in patients (p = 0.007, controls upsilon patients). Blood flow at 90 mu g/min oflosartan correlated with plasma angiotensin II concentra tion (r = 0.77; p = 0.03). Responses to angiotensin II and noradrenali ne did not differ between patients and controls. Conclusions-Losartan causes acute local peripheral arteriolar vasodilatation in patients wi th heart failure but not in healthy control subjects. Endogenous angio tensin LI directly contributes to basal peripheral arteriolar tone in patients with heart failure but does not augment sympathetically stimu lated peripheral vascular tone.