Abstract 2970: Mechanism of Increased Susceptibility of Youth to Sudden Death with Chest Wall Impact (Commotio Cordis)

Background. Commotio cordis (CC), sudden cardiac death secondary to blunt, innocent-appearing chest wall blows in sports and other daily activities, is being reported with increasing frequency. Children and adolescents are most at-risk for this phenomenon. In an experimental animal model, it has been shown that ventricular fibrillation (VF) can be induced with a baseball blow to the chest wall during the vulnerable period of repolarization. We hypothesized that in this model, larger subjects would require higher impact velocities to induce VF. Methods. Under general anesthesia, 41 juvenile swine (16 to 55 kg) were placed prone in a sling and received chest wall blows at 30 to 60 mph with a lacrosse ball aimed directly over the cardiac silhouette. Impacts were timed to occur during the vulnerable period for VF (10 –30 ms prior to the T-wave peak). Animals were divided into 4 groups based on weight (16 to 25kg, 26 to 35kg, 36 to 45kg, and 46 to 55kg) and the frequency of VF was analyzed. Results. In 419 impacts, the smallest animals (16 to 25kg) were most vulnerable to VF and incidence of VF decreased incrementally as animal size increased. Impacts at 30 mph only induced VF in the smallest animals. In the largest animals (46 to 55kg), VF was only induced at impacts of 60 mph (figure ). Conclusion. Impact velocity and subject size are important variables in the generation of CC. In this animal model, smaller animals are more vulnerable to generation of VF across a wider range of impact velocities. These data might underlie the higher vulnerability to CC that has been observed in children and young adults and has implications for the prevention of CC with chest wall protectors.