Coronary Vasodilator Capacity and Epicardial Vessel Remodeling in Physiological and Hypertensive Hypertrophy

Abstract

Abstract —The aim of this study was to compare resting coronary flow velocity, determinants of myocardial oxygen demand, and coronary vasodilator capacity in subjects with physiological, exercise-induced, and hypertensive left ventricular hypertrophy. Sixteen healthy sedentary men, 16 endurance athletes, and 16 hypertensive subjects (mean±SEM for left ventricular mass index: 94.9±5.5, 184.6±8.4, 154.4±9.5 g/m 2 , respectively) were studied by transesophageal and transthoracic Doppler echocardiography. Coronary flow velocity in left anterior descending artery and cross-sectional area of left main artery were assessed at rest and during dipyridamole-induced vasodilation. Myocardial oxygen demand was estimated through rate-pressure product, left ventricular wall stress, and inotropic function. Coronary flow reserve and minimum coronary resistance were comparable to those of sedentary men in athletes (mean±SEM: 3.23±0.16 versus 3.60±0.18 and 0.96±0.06 versus 1.04±0.04 mm Hg · s · cm − 1 ), while in hypertensive subjects they were decreased and increased, respectively (mean±SEM: 2.31±0.08 and 1.21±0.10 mm Hg · s · cm − 1 ; P <0.05 for both). Resting flow velocity was directly related to rate-pressure product in sedentary men and athletes and also to wall stress in athletes, while these correlations were absent in hypertensives. Dilation of left main artery after dipyridamole was significantly higher in athletes than in sedentary men and hypertensive subjects (mean±SEM for area change: 32.9±3.7% versus 12.8±2.5% and 6.4±3.3%; P <0.05 and 0.01). These data indicate that vasodilator capacity of coronary microcirculation is not impaired in athletes with physiological hypertrophy, in contrast to hypertensive patients. The relationship between resting flow velocity and determinants of oxygen demand is preserved in physiological hypertrophy but missing in hypertensive hypertrophy. Furthermore, the vasodilator capacity of coronary macrocirculation is also enhanced in exercise-trained subjects.