Intravascular bullet embolization is a rare phenomenon with potentially devastating consequences. Projectiles have been reported to migrate within the arterial and venous circulation, resulting in life-threatening injuries from the initial injury as well as from the migration event (1). Herein, we report a case of a bullet migration to the descending thoracic aorta during catheter angiography, which was successfully treated with endovascular snare retrieval. Our institution does not require institutional review board approval for the publication of retrospective case reports such as this.
A 44-year-old man was seen at an outside institution following a gunshot wound to his right chest. A single bullet entered the right upper arm and continued into the thorax. There was no exit wound. He underwent right tube thoracostomy for hemothorax and was discharged several days later after removal of the catheter. He presented to our institution 4 days after his previous discharge with continued shortness of breath, as well as severe intermittent chest pain. His initial workup, including chest computed tomography (CT), showed a persistent loculated right pleural effusion, and a metallic object consistent with a .22 caliber bullet at the base of the heart (Figure, a). This was believed to be located in the region of the transverse sinus abutting the aortic root, but not definitively intraluminal. This was reported at the same location on initial CT scan evaluation at the outside institution. There was no evidence of a significant mediastinal hematoma. An echocardiogram showed only a very small pericardial effusion.
The interventional radiology service was consulted for treatment of his right pleural effusion, and a 14-F pigtail catheter was placed, which yielded 450 mL of bloody fluid. An arch aortogram was also requested given the patient's persistent chest pain and proximity of the projectile to the aortic root.
Before the initial injection of contrast for the arch arteriogram, the bullet was noted to be located in the projection of the aortic root (Figure, b). A pigtail catheter was positioned in the proximal ascending aorta and contrast was injected at a rate of 20 mL/sec for a total of 40 mL. After near-complete injection of the contrast material during the angiography procedure, the bullet was seen to migrate to the mid-descending thoracic aorta (Figure, c). The bullet remained at this site without further migration. (Also see the video, available for viewing at www.jvir.org.)
After consultation with cardiac and vascular surgery services, a decision was made to attempt a snare retrieval of the bullet. A 20-mm Amplatz Goose Neck snare (ev3, Plymouth, Minnesota) was then advanced to the descending thoracic aorta. The loop was passed around the bullet and tightened, successfully engaging the projectile (Figure, d). The bullet was then withdrawn to the proximal right common femoral artery at the tip of the sheath. The patient was then transferred to the operating room, where right femoral cutdown was performed, and the bullet was completely removed by the surgeon. Extracted was a copper point bullet measuring 1.1 cm × 0.4 cm.
The patient underwent uneventful closure of his femoral arteriotomy, and following a several-day postoperative recovery period he was discharged to home without further sequelae. Upon discharge, he was asymptomatic, with no chest pain, and no signs of stroke, transient ischemic attack, or limb ischemia.
Penetrating trauma resulting in intravascular bullet embolization is rare in clinical practice. Embolization is more commonly encountered in the arterial than the venous system. In an extensive review of 153 cases by Michelassi et al (2), 80% of arterial embolizations were symptomatic, whereas venous bullet emboli were only symptomatic in one third. In general, smaller-caliber bullets are more frequently seen to embolize. Shen et al (3) reviewed 18 cases of missile arterial embolization and found 50% of cases to be from .22 caliber bullets.
Our case also involved a .22 caliber bullet, with a theorized route of entry being passage through the chest wall and lung parenchyma into a pulmonary vein with subsequent immediate embolization to the left ventricular outflow tract, with the bullet remaining in the aortic root about the sinuses of Valsalva until subsequent migration during catheter angiography. Bradham et al (4) reported a case of bullet embolism to the base of the aortic root; the bullet was surgically removed. An entrance wound was never found, but it was theorized that entry occurred by way of a pulmonary vein.
It is also noteworthy that the patient had persistent intermittent chest pain, prompting the request for the arteriogram. It was theorized that the bullet was possibly producing intermittent coronary artery obstruction. After retrieval, the patient's symptoms did resolve.
Although there are many cases of bullet snare retrieval reported within the venous system, to our knowledge, this case represents the second reported case in the literature of a successful intraarterial endovascular snare retrieval of a bullet, permitting safe surgical removal. Reil et al (5) reported a similar successful snare retrieval from the thoracic aorta, with the bullet size limiting withdrawal to the common iliac artery, where arteriotomy was ultimately performed for surgical extraction. Their case involved arterial embolization resulting from direct penetration of the left ventricle, requiring emergent thoracotomy. In most cases of arterial embolization, the bullet will lodge at a bifurcation or change in caliber of the vessel. This position can make attempts at a safe snare retrieval technically challenging.
Our review of the literature does not show any reported cases of arterial bullet migration induced by the jet of contrast material during arteriography. It was surprising to us at the time that the bullet remained in the mid-thoracic aorta, maintaining an intraluminal position and allowing for snare retrieval. A likely explanation is that this represented the most dependent portion of the thoracic aorta, with the weight of the bullet greater than the force of antegrade arterial blood flow. Additionally, the linear irregularities on the surface of the bullet may have provided added friction, preventing further migration.
When bullet embolization is suspected, management schemes will depend on hemodynamic status, and will usually begin with a CT scan and angiography if the patient's clinical condition permits (1). Intravascular ultrasonography could also be considered if an intraluminal location is suspected. Percutaneous extraction should then be considered if feasible. Emergent surgical exploration will often be necessary, especially in arterial embolization cases.
In summary, a bullet embolus to the thoracic aorta was able to be successfully treated with endovascular snare retrieval, permitting safe surgical removal. This should be considered as a valuable option in select circumstances.
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