Sudden death following blunt chest trauma is a frightening occurrence known as 
'commotio cordis' or 'concussion of the heart'. It is speculated that commotio 
cordis could be caused by ventricular fibrillation secondary to an 
impact-induced energy that was transmitted via the chest wall to the myocardium 
during its vulnerable repolarization period. We describe a survivor of commotio 
cordis caused by a baseball. In this patient, an initial ventricular 
fibrillation was documented and converted by direct current defibrillation. 
Serial electrocardiographic changes (bifascicular conduction block and T wave 
inversion in precordial leads) were noticed in this patient. Our case suggested 
that coronary vasospasm might also play a role in commotio cordis.