[Target heart rate for exercise echocardiography].

The exercise stress test with a semi-supine position bicycle ergometer was evaluated in 10 normal subjects and five cardiac patients to define the appropriate target heart rate for exercise echocardiography. The normal healthy subjects were aged between 24 and 30 years, while the five patients with artificial aortic valves were aged between 13 and 54 years. The workload was continuously increased from 0 W to the maximum achieved workload at 20 W/min for normal subjects and 10 W/min for patients. Echocardiography was recorded every minute during the test procedure. End-diastolic and end-systolic dimensions were measured and ejection fraction was calculated. The ejection fraction at heart rates 50, 60, 70 and 80% of predicted maximum heart rate and at maximum workload were compared. Heart rates at the maximum workload for normal subjects were 76 to 94% (86.3 +/- 6.3%) of the maximum heart rate predicted from the age of the subjects and 70 to 102% (84.0 +/- 12.6%) for the patients. The largest election fraction values during exercise stress were obtained at 70% of the maximum predicted heart rate in normal subjects, and at 60% in the patients. The target heart rate for exercise echocardiography is 70% of the maximum calculated heart rate.