[Effect of exercise on systolic left ventricular outflow velocity in healthy adults].

The occurrence of exercise-induced dynamic obstruction of the left ventricular outflow tract in patients without cardiomyopathy has recently been reported. However, it is not known if this phenomenon is a normal response to exercise in healthy adults. We studied 23 healthy adults using exercise Doppler echocardiography. We measured the left ventricular outflow velocity at rest and after maximum tolerated exercise. After a mean exercise duration of 12 min 45 s (2 min 32 s), the heart rate was 97.61 (6.71)% of the theoretical maximum. Left ventricular outflow velocity increased from 1.07 (0.18) m/s (range: 0.77-1.44 m/s) to 1.58 (0.35) m/s (range: 1.09-2.4 m/s). In healthy adults, exercise increased the left ventricular outflow velocity by 50%, though in no subject was it greater than 2.5 m/s. This observation appears to rule out the possibility that a high intraventricular pressure gradient is a normal response to exercise in healthy adults.