Tasneem Z. Naqvi, MD: From Division of Cardiology, Cedars-Sinai Medical Center, Los Angeles, California.

A number of electrocardiographic abnormalities have been described in athletes.1 Among these are sinus bradycardia and varying degrees of atrioventricular (AV) block. These findings have been attributed to the "athlete's heart," and are felt to be due to enhanced vagal tone seen with excellent physical conditioning. Secondarily it has also been suggested that there are intrinsic changes within the sinoatrial and AV nodes themselves, including prolonged sinus node recovery time and AV nodal Wenckebach, and these abnormalities persist following autonomic blockade.