COMPARISON OF ISRADIPINE AND ENALAPRIL EFFECTS ON REGIONAL CAROTID CIRCULATION IN PATIENTS WITH HYPERTENSION WITH UNILATERAL INTERNAL CAROTID-ARTERY STENOSIS

This randomized, double-blind, placebo-controlled study was aimed at d etecting cerebrovascular effects of isradipine and enalapril in patien ts with moderate hypertension depending on the presence and grade on u nilateral stenosis of internal carotid artery (ICA). We evaluated caro tid vascular resistance by using Doppler analysis and regional cerebra l blood flow (rCBF) by using Xe-133-clearance technique before and aft er a single 5-mg oral dose of isradipine, enalapril, or placebo. Their effects were randomly and consecutively tested in 73 patients with es sential hypertension subdivided into three groups: without carotid occ lusive lesions, with moderate (50-75%), and with severe (76-99%) unila teral asymptomatic ICA stenosis. There were no differences in age, gen der, and antihypertensive effects of the drugs between these three sub groups. Three major variants of cerebrovascular drug effects were obse rved: absence of changes (variant I), decrease in carotid vascular res istance with increase in rCBF and elimination of side-to-side asymmetr y (variant II), and increase in carotid vascular resistance with furth er reduction of rCBF ipsilaterally ICA stenosis, and increased side-to -side asymmetry (variant III). Frequency of variant III was significan tly higher in patients with severe ICA stenosis. Enalapril produced va riant I of cerebrovascular effects in most patients examined; variant III was observed only in 13% of patients with severe ICA stenosis. Isr adipine produced variant I of cerebrovascular effects much less freque ntly than did enalapril. For this drug, variant II was most typical in patients without ICA stenosis and with moderate ICA stenosis. In 43.5 % of patients with severe ICA stenosis, however, isradipine produced r eduction of cerebral perfusion. Presumably the presence of ICA stenosi s, especially >75%, increases the risk of cerebrovascular disorders in antihypertensive therapy. In patients with severe ICA stenosis, treat ment with enalapril appears to be safer than that with isradipine.