Experimental cardiac trauma--ballistics of a captive bolt pistol.

Cardiac trauma can be experimentally produced by blunt impulsive impact over the cardiac apex in the anesthetized canine. A gradation of myocardial injury, including transient arrhythmia, contusion, and lethal ventricular fibrillation, can be produced by varying the power of the charge in a modified captive bolt pistol. Ballistics experiments were conducted to quantify the velocity, energy, and trajectory of impacts produced by the modified captive bolt pistol using various charges. Correlation of the impact data with the previously reported levels of trauma indicates that a 24 m/s impact with 178 joules of available energy results in lethal ventricular fibrillation with extensive myocardial contusion. Blunt impact at 17 m/s with 102 joules causes serious myocardial injury and at 13 m/s with 67 joules causes minor transient arrhythmia.