Impact directly over the cardiac silhouette is necessary to produce ventricular fibrillation in an experimental model of commotio cordis.

OBJECTIVES In an experimental model of sudden death from chest wall impact (commotio cordis), we sought to define the chest wall areas important in the initiation of ventricular fibrillation (VF). BACKGROUND Sudden death can result from an innocent chest blow by a baseball or other projectile. Observations in humans suggest that these lethal blows occur over the precordium. However, the precise location of impact relative to the risk of sudden death is unknown. METHODS Fifteen swine received 178 chest impacts with a regulation baseball delivered at 30 mph at three sites over the cardiac silhouette (i.e., directly over the center, base or apex of the left ventricle [LV]) and four noncardiac sites on the left and right chest wall. Chest blows were gated to the vulnerable portion of the cardiac cycle for the induction of VF. RESULTS Only chest impacts directly over the heart triggered VF (12 of 78: 15% vs. 0 of 100 for noncardiac sites: p < 0.0001). Blows over the center of the heart (7 of 23; 30%) were more likely to initiate VF than impacts at other precordial sites (5 of 55; 9%, p = 0.02). Peak LV pressures generated instantaneously by the chest impact were directly related to the risk of VF (p < 0.0006). CONCLUSIONS For nonpenetrating, low-energy chest blows to cause sudden death, impact must occur directly over the heart. Initiation of VF may be mediated by an abrupt and substantial increase in intracardiac pressure. Prevention of sudden death from chest blows during sports requires that protective equipment be designed to cover all portions of the chest wall that overlie the heart, even during body movements and positional changes that may occur with athletic activities.