Commotio cordis: size matters, so does shape

Abstract

O h d b s H g s L Sudden cardiac death in young athletes is a devastating event that is typically caused by unrecognized cardiovascular diseases. However, it can also happen in young, healthy athletes who are free of any form of heart disease when a blow to the chest occurs during the vulnerable period of repolarization and ventricular fibrillation (VF) is induced, that is, commotio cordis. It has long been known that externally applied mechanical forces can stimulate the heart electrically. The phenomenon is called mechanoelectrical coupling and is mediated by stretch-activated ion channels. In 1920, Schott decribed how a sharp impact with a fist to the lower half of he sternum could pace the asystolic heart of individuals ith Stokes-Adams syndrome. In 1930, Hyman observed hat the insertion of a needle into the myocardium (to eliver drugs during asystole) was by itself capable of epolarizing the heart. These are probably some of the first eports of mechanoelectrical coupling. The phenomenon is now well described in different setings with a wide range of externally applied mechanical orces. In 1976, Zoll et al developed an external mechanical cardiac stimulator using an electrically powered stapling gun. Atrial and ventricular premature contractions were triggered by applying the device to different areas of the chest. More recently, it has been reported that chest compressions can electrically stimulate the heart in an animal model as well as in humans during out-of-hospital PR, which may trigger VF. Commotio cordis is the second leading cause of death in outh athletes in the United States and has been extenively studied. The importance of the velocity and of the timing of blows to the chest during the cardiac cycle in the generation of VF has been well described in an animal model. Therefore, it is now widely accepted that an exernally applied mechanical force, if sufficiently strong, can lectrically stimulate the heart and, if sufficiently strong, imed to the vulnerable period of repolarization, and aimed irectly at the precordial area, can cause VF.