Commotio Cordis -- Sudden Cardiac Death With Chest Wall Impact

Christopher Madias, M.D.; Barry J. Maron, M.D.; Jonathan Weinstock, M.D.; N. A. Mark Estes III, M.D.; Mark S. Link, M.D.

Disclosures

J Cardiovasc Electrophysiol. 2007;18(1):115-122. 

In This Article

Prevention and Treatment

Deaths from sports-related CC are tragic and have triggered considerable interest in developing preventive strategies. Several approaches have been proposed, including increasing the use of softer baseballs and chest wall protectors in competitive sports. Safety baseballs with soft rubber cores have been designed to reduce the risk of head and other bodily injury from traumatic impacts. In our experimental model, safety baseballs significantly reduced, but did not eliminate, the risk of sudden cardiac death with chest impacts at 30 and 40 mph.[19,23] The softest safety baseballs triggered VF in only 11% of chest impacts compared to 69% of impacts with standard baseballs (Fig. 2). Despite these findings, as well as the consensus that safety baseballs reduce serious bodily trauma, obstacles to widespread use of safety baseballs in youth sports remain.[23] The softer core of these baseballs often results in exaggerated bounce on turf and slower velocities after being struck by a bat. Because of these factors, critics feel that safety baseballs alter the fundamental nature of the game. However, safety baseballs of intermediate grades of hardness largely maintain the qualities of standard baseballs and should be a reasonable, safer option in youth baseball.[23]

Current commercially available chest protectors are marketed with claims of protecting sports participants from harm owing to chest wall trauma. However, in the U.S. Commotio Cordis Registry, more than 25% of fatal impacts that occurred during organized competition involved individuals wearing a chest protector.[1] Because of migration of the protector in the course of competition, impacts occurred directly on the chest wall of the victim in some of these cases. In other cases, however, projectiles were known to strike on the chest protector, which failed to prevent the fatal CC event. Recently, we assessed the effectiveness of commercially available lacrosse and baseball chest protectors for the prevention of sudden cardiac death in our CC model.[25] Representative portions of 12 different lacrosse and baseball chest protectors were securely affixed to the chest of the animals that sustained impacts at 40 mph. None of the currently available chest protectors tested in our swine model was shown to significantly decrease the occurrence of VF when compared to controls (Fig. 4). In accord with our previous findings, peak LV pressure produced by chest wall impacts correlated linearly with the probability of VF in these experiments. The majority of the chest protectors evaluated in these studies were composed of a compliant layer or layers of closed cell foam of varying thickness and density that is intended to dissipate the energy of an impact. The ineffectiveness of this design in reducing the incidence of VF is likely due to its inability to adequately reduce the peak LV pressure generated by chest wall impact. Viano et al. also examined the effectiveness of five commercial chest protectors in reducing the risk of CC.[36] Using a three-rib biomechanical dummy model, only one of the five chest protectors consistently decreased the risk of CC as measured by the ability to significantly reduce the viscous criterion of baseball impacts at velocities of 40-70 mph. The viscous criterion is the product of the velocity and amount of compression caused by chest impacts and has been shown to correlate with the risk of trauma as well as the development of fatal arrhythmias from chest wall blows. Further research on the development of an adequate chest protector for the prevention of CC is needed.

Incidence of ventricular fibrillation with baseball and lacrosse ball chest impacts for each of eight baseball chest protectors and seven lacrosse chest protectors versus controls. Numbers above bars are P values calculated for chest protectors versus controls.[25] Reprinted with permission from The American Academy of Pediatrics.

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