ECG Quiz: An Irregular Pulse in a Skydiver
John D. Cantwell, MDTHE PHYSICIAN AND SPORTSMEDICINE - VOL 24 - NO. 1 - JANUARY 96
A 29-year-old man was referred to a cardiologist after an irregular heartbeat was found on a preemployment physical examination. He had no cardiac or pulmonary symptoms.
Past illness or surgery included only several operations for ocular strabismus. He took no medications. His weekly alcohol intake included six beers, two shots of hard liquor, and six or seven glasses of wine. He averaged one-fourth pack of cigarettes per day over the past 9 months, but had not smoked previously.
His exercise habits included skydiving (two to five jumps per weekend), running 6 miles three times per week, and lifting weights for 1 hour two to three times per week. His father was hypertensive. There was no family history of early coronary disease, arrhythmia, or sudden death. The systems review indicated a single syncopal episode 6 years earlier while lifting weights after having donated blood.
On physical examination the patient's blood pressure was 115/82 mm Hg, and his pulse was 54 per minute and irregular. Neck and chest evaluations were normal. The heart was not enlarged. A grade 1/6 short systolic ejection murmur was heard at the upper and midleft sternal border, and diminished with Valsalva's maneuver and with standing. His first heart sound quieted progressively on an intermittent basis in cycles of three or four. The complete blood count and biochemical profile were normal. His total cholesterol level was 135 mg/dL and his HDL was 45 mg/dL.
His resting electrocardiogram (ECG) is shown in figure 1. His Bruce protocol treadmill test was normal; he had a duration of 16 minutes, stopping because of fatigue.
Why did his first heart sound soften progressively and cyclically? Based on your interpretation and diagnosis, do you think he should be hired for a demanding job that involves a certain amount of emotional stress?
Dr Cantwell is director of preventive medicine and cardiac rehabilitation at Georgia Baptist Medical Center and clinical professor of medicine at Morehouse School of Medicine in Atlanta. He is a member of the editorial board of The Physician and Sportsmedicine and chief medical officer of the 1996 Centennial Olympic Games. Address correspondence to John D. Cantwell, MD, 340 Boulevard NE, Suite 200, Box 413, Atlanta, GA 30312.