Laceration of the thoracic aorta from a .22 lr bullet

A gunshot wound (.22 long rifle) to the chest including perforation of the aorta ascendens is presented. The small wound tract in soft tissue was characteristic for this type of ammunition and did not show any special peculiarities. However, arterial injury was not restricted to two small perforations, as expected in the light of previous wound ballistic findings. Three large longitudinal ruptures (3.0-4.5 cm in length and two of them independent of the perforations) additionally occurred, which led to rapid exsanguination. This extraordinary extent of vascular injury can be explained by perforation of the artery during the ventricular ejection phase, which causes a considerable dilation of the aorta analogous to a windkessel. The pre-existing dilation enables intraluminal temporary cavitation to have an "explosive" effect despite the high elastic tolerance to the vessel wall. The importance of tissue characteristics in gunshot wounds in general and the possible role of temporary cavitation inside the vessel in vascular gunshot wound production in particular are stressed.