Effects of age on aortic blood velocity at rest and during exercise in patients with coronary artery disease.

The effect of age on aortic blood velocity has been studied in 100 patients with angiographically-documented coronary artery disease, 500 of whom were receiving beta-adrenergic blocking agents. Using continuous-wave Doppler ultrasound, the aortic blood velocity signals, both at rest and at maximal-tolerated supine exercise, were obtained. From the Doppler signals the peak velocity (Vp), stroke distance (Sd; the velocity-time integral) and minute distance (Md = Sd x heart rate) were calculated. The measurements were repeated 6 weeks after coronary artery bypass grafting (CABG), performed in 30 patients. No relationship with age (p < 0.01) was found for any of the indices, either at rest or during exercise, except for the resting Md in patients not on beta-blockers, (p < 0.02). No difference in the slope of the relationship with age was found between patients on or not on beta-blockers, except for the resting Md (p < 0.02). Following CABG, a significant age relationship with Vp, Sd and Md was restored, during both resting and exercise, suggesting improvement of systolic left ventricular function following myocardial revascularization. In conclusion, the normal age relationships of the derivatives of aortic blood velocity Doppler ultrasound signals were not seen in patients with coronary artery disease, irrespective of whether they were on or off beta-blockers. The relationship changed following myocardial revascularization, suggesting their dependence on systolic left ventricular function.