Malignant arrhythmias during strenuous work in four young men.

Four young healthy men (17-25 years old) experienced life-threatening arrhythmias during physical exertion. All were successfully resuscitated. One died later. Electrophysiological studies disclosed a lack of normal conduction delay and abnormal His-Purkinje properties indicating congenital malformation of the atrioventricular (AV) node in one patient and the rare and potentially dangerous combination of an accessory AV pathway and intra-atrial conduction delay with liability to dissimilar rhythms and fibrillation in the atria in another. The conduction system functioned normally in the other two. One of the latter two patients had cerebral damage during prolonged resuscitation and experienced repeated epileptic spells until he died unexpectedly. Autopsy revealed scarring of unknown origin in the interventricular septum. The other had stress-induced ventricular ectopy, which gradually diminished and disappeared in a few weeks. The etiology of the latter two is suggested to be ischemia. It is warranted to point out the possible danger of maximal physical strain even in young people.