Autonomic function and the sinus tachycardia of Duchenne muscular dystrophy.

The cardiovascular autonomic function of 13 boys with Duchenne muscular dystrophy was examined in order to test the hypothesis that the labile sinus tachycardia of that disorder is due to autonomic dysfunction. Five non-invasive procedures evaluated the responses of heart rate and blood pressure to postural change, the Valsalva maneuver, sustained hand grip and deep breathing. No individual had sufficient evidence of autonomic dysfunction. Most tests were normal (76%), 16% were borderline, and 8% were abnormal. None had more than one abnormal test. Although most had some difficulty with the Valsalva maneuver, the study demonstrated that simple clinical non-invasive testing of autonomic function can be carried out on a young severely handicapped population.