Coronary Circulation in Arterial Hypertension

Abstract

Arterial hypertension is the most common cause of congestive heart failure and an important risk factor in coronary artery disease (CAD). However, even in the absence of CAD, coronary reserve is frequently impaired in hypertensive patients. To study whether the reduced coronary reserve is due to the degree of left ventricular hypertrophy (LVH) or is a consequence of primary vascular alterations, coronary reserve was determined in 31 hypertensive patients (age of 56 +/- 10 years; systolic/diastolic blood pressure of 167 +/- 18/98 +/- 9 mm Hg) with angina pectoris and normal coronary angiogram. Coronary reserve was determined by measuring coronary resistance before and after dipyridamole (0.5 mg/kg of body weight i.v.). Coronary blood flow was measured quantitatively by the gas chromatographic argon method. LV muscle mass was measured by ventriculography. Twelve normotensive patients (age of 52 +/- 8 years) were studied for comparison. Coronary resistance was 20% higher in hypertensive than in normotensive patients, whereas coronary blood flow at rest was not significantly different. The maximal coronary blood flow after dipyridamole was 40% lower in hypertensive than in normotensive patients; accordingly, minimal coronary resistance was significantly increased by 112% in hypertensive patients (p less than 0.0005). Coronary reserve was reduced by 37% (p less than 0.001) in hypertensive patients compared with normotensive patients. Between the impairment in coronary reserve and left ventricular muscle mass, no significant correlation (r = 0.024, n.s.) was found. The impaired coronary vasodilator reserve is reflected by episodes of transient myocardial ischemia during ST-segment monitoring.