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 th e initiation of ventricular fibrillation (VF). BACKGROUND Sudden death can result from an innocent chest blow by a basebal l or other projectile. Observations in humans suggest that these lethal blo ws occur over the precordium. However, the precise location of impact relat ive 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., dire ctly over the center, base or apex of the left ventricle [LV]) and four non cardiac sites on the left and right chest wall. Chest blows were gated to t he 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 o f 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 V F (p < 0.0006). CONCLUSIONS For nonpenetrating, low-energy chest blows to cause sudden deat h, impact must occur directly over the heart. Initiation of VF may be media ted by an abrupt and substantial increase in intracardiac pressure. Prevent ion 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 occu r with athletic activities. (C) 2001 by the American College of Cardiology.