Bullet Emboli

Vascular embolization of a bullet is an uncommon occurrence. When it does occur, it usually involves the arterial system. Embolization should be suspected whenever there is a penetrating bullet wound with failure to discover the bullet in the expected region or to visualize the bullet on routine x-ray.9 In the author's first encounter with a case of bullet embolization, he spent seven hours looking for a bullet in the chest and abdomen, when it was in the femoral artery (there was no x-ray equipment).

The most common sites of entrance for a bullet into the arterial system are the aorta and the heart. In a review of 153 cases of bullet emboli in the English-language literature, there were 100 cases of embolism to the arterial circulation and 53 to the venous.10 The source of the embolism to the arterial circulation was the thoracic aorta in 37.9% of cases, the heart in 34.4% cases, and the abdominal aorta in 15.5% cases. The sources of the emboli to the venous circulation were the vena cava in 23.5% (the inferior vena cava was 20.6%), the iliac veins 29.4%, and the heart 17.6%. The bullets generally followed the direction of the blood flow though 14.7% of venous bullets followed a retrograde path. Although embolization usually occurs immediately following entrance of the bullet into the circulation, delays as long as 26 days have been reported.11 The site of lodgment of the bullet is predominantly the right side of the heart and the pulmonary arteries for bullets entering the venous system and the lower extremities for bullets entering the systemic circulation. Whether there is predominant embolization to the right or left legs is debatable.9 Embolization to the brain is rare. Virtually all such cases involve shotgun pellets.12

Bullet emboli are usually associated with small caliber, low-velocity missiles. Thus, in the review by DiMaio and DiMaio, in the 24 instances in which the caliber or type of weapon was known, a .22-caliber bullet accounted for 14 cases, an airgun pellet for 2 cases, and a shotgun pellet for 2 cases.9 These missiles are all small-caliber, lightweight, low-velocity projectiles possessing low kinetic energy and usually causing penetrating rather than perforating wounds. If these missiles lose their forward velocity on penetration of a major blood vessel or the heart, they will be swept along by the blood to their final point of lodgement.

If an x-ray is not taken before autopsy, a bullet embolus secondary to a gunshot wound of the aorta may not be suspected because of the presence of both an entrance and an exit in this vessel. In such a case, the almost spent bullet, after exiting the aorta, strikes the vertebral column and rebounds back through the exit into the lumen of the aorta, where it is swept away to a lower extremity.

Bullet emboli may occur from wounds other than those in the chest and abdomen. In one of the author's cases, an individual was shot in the left eye with a .22-caliber bullet. The bullet entered the cranial cavity, traveled through the left cerebral hemisphere, and ricocheted off the inner table of the skull, penetrating into the left straight sinus. It was carried through the venous system, down the jugular vein, through the right atrium and ventricle, and into the pulmonary artery. The bullet came to rest lodged in a major branch of the left pulmonary artery.

A variant of the bullet embolus not involving vascular embolization is occasionally encountered. One such case involved an individual shot in the right back. The bullet traveled upward into the oral cavity, where it subsequently was coughed or vomited up by the victim. The bullet was found on the ground a number of feet away from the deceased in a pool of vomitus and blood. In another case, an individual incurred a gunshot wound of the chest. On admission to the hospital, the bullet was seen on x-ray apparently lodged in the parenchyma of the right lung. The individual survived a number of days in the hospital. At autopsy, the bullet was found in the bronchus of the left lung. Apparently the bullet entered the bronchial tree on the right side and subsequently was coughed up and aspirated into the left bronchial tree.

0 0

Post a comment