Mechanisms and Prevention of Commotio Cordis: Use in an Animal Model
Principal Investigator: Mark S. Link, M.D.
Institution: The New England Medical Center Hospital
Title: Decreasing the Risk of Commotio Cordis: Sudden Death from Low Energy Chest Wall Impact.
Abstract: Death due to minor chest wall trauma, commotio cordis, is seen in young athletes aged 5 to 16. Although not common, it is the most frequent cause of death in the young basketball player. Death is swift and unusually recalcitrant to even immediate resuscitation efforts. We have recently developed an animal model with low energy chest wall impact gated to the cardiac cycle. With this model we have found that if an impact is during a 15 millisecond window on the upslope of the T-wave, ventricular fibrillation can result. Ventricular fibrillation was not produced during any other time period of the cardiac cycle. If the impact occurred during the QRS segment, transient complete heart block may result. ST segment elevation was seen with impacts throughout the cardiac cycle.
Using this swine model we have found that softer baseballs (thrown at 30 mph) decrease the risk of commotio cordis. We have also found that the risk of ventricullar fibrillation increases as the velocity of the baseball increases to 40 mph, but then, unexpectedly decreases as the ball speed is increased to 50 or 60 mph.
Over the next two years, our goal is to use this model of commotio cordis in order to more fully evaluate the pathophysiology, prevention and treatment of commotio cordis. We will evaluate the influence of the size and chest wall compliance of the animal and area of impact. We will continue to evaluate safety baseballs and other preventative measures (including chest wall protection) for this devastating condition. We will also evaluate resuscitative measures for the ventricular fibrillation that we have produced.
To accomplish these goals, we will continue to use and develop our model using juvenile swine. Fully anesthetized and monitored animals will be placed in a swing, and an impact will be directed to the chest that is gated to the cardiac cycle. Electrophysiologic abnormalities will be monitored with continuous 6 lead EKGs. In early studies, the swine used will be incrementally increased in size. The area of chest wall impact will be varied. Safety ball impact will be performed at a higher velocity (40 mph). Chest wall protectors will be assessed for their ability to prevent commotio cordis.
The endpoints of this study will be to more fully understand the mechanism, prevention and treatment of commotio cordis. The knowledge gained from this study will add to our understanding of the mechanism of not only commotio cordis, but of basic electrophysiology. In addition, the use of this model in evaluating safety baseballs and protective equipment will add much needed information to discussions of public issues in the sports arena.