Ann Thorac Surg 1998;66:562-564
© 1998 The Society of Thoracic Surgeons
Case Reports
Paradoxical embolism of a shotgun pellet
John S. Ikonomidis, MD, PhDa,
Steven J. Nisco, MDa,
David H. Liang, MD, PhDb,
Robert C. Robbins, MDa
a Department of Cardiothoracic Surgery, Stanford Health Services, Stanford, California, USA
b Department of Cardiovascular Medicine, Stanford Health Services, Stanford, California, USA
Accepted for publication February 28, 1998.
Address reprint requests to Dr Robbins, Department of Cardiothoracic Surgery, Falk Cardiovascular Research Center, Stanford Health Services, Stanford, CA 94305-5247
e-mail: (robbins{at}leland.stanford.edu)
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Abstract
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Paradoxical embolism of a projectile from the venous to arterial system is a rare occurrence, which can cause diagnostic confusion. We present a case of venous embolism of a shotgun pellet from the left upper extremity to the noncoronary sinus of the aortic valve across a secundum-type atrial septal defect. Prevention of distal embolism of the pellet was presumably a result of its containment by flow vortices created within the sinuses of Valsalva.
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Introduction
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Bullet emboli are unusual occurrences. Entrance into the venous system by a projectile may result in embolization to the venae cavae or the heart. In exceptionally rare instances, the projectile may cross as a paradoxical embolus into the arterial circulation and embolize to distant sites. We describe a case of a paradoxical shotgun pellet embolism from the left upper extremity to the noncoronary sinus of the aortic valve via a secundum-type atrial septal defect.
A 31-year-old woman presented to the Emergency Department with wounds from a single 12-gauge shotgun blast. The patient was hemodynamically stable and complained of chest pain, shortness of breath, and left arm weakness. Examination revealed a large left neck hematoma and pellet wounds concentrated in the left neck and shoulder. Breath sounds were clear bilaterally. Cardiac auscultation was unremarkable. Neurologic examination revealed evidence of left hand weakness. An anteroposterior roentgenogram showed a small left pleural effusion with associated atelectasis and multiple pellets in the chest wall. Left upper extremity roentgenograms showed no evidence of bony injury. A contrast esophagogram was normal. An arteriogram was performed, which showed no evidence of aortic arch or great vessel injury. However, a pellet was seen to be lying in or near the heart (Fig 1). This pellet appeared to move with each cardiac contraction but showed no evidence of dislodging.
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Fig 1. Aortogram showing a small, round object associated with the noncoronary sinus of the aortic valve.
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A computed tomogram of the chest showed a small foreign body in the heart, occupying the right or left atrium or interatrial septum (Fig 2). The aortic arch and descending thoracic aorta were surrounded by material consistent with a hematoma. A transesophageal echocardiogram revealed normal left ventricular size, thickness, and contractility with no evidence of effusion. In addition, a 1.2 x 1.2-cm atrial septal defect was identified, with foreign material sitting in the noncoronary cusp of the aortic valve (Fig 3).
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Fig 2. Computed tomographic scan of the chest showing artifactual scatter consistent with a metallic foreign body within the heart.
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Fig 3. Transesophageal echocardiogram. (A) The embolized pellet (arrow) within the noncoronary sinus of the aortic valve. (B) Atrial septal defect (dark arrow); also shown is the pellet (light arrow) within the aortic valve. (Ao = aorta; LA = left atrium; RA = right atrium.)
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As there was no evidence of direct coexisting cardiac injury, it was thought that venous embolism was the likely route of entry of the pellet into the heart. Operation was recommended to the patient to extract the pellet because its exact position in the heart was uncertain, and because the finding of an atrial septal defect raised the possibility of paradoxical embolism.
After median sternotomy, a small ecchymotic reaction was noted along the left lateral aspect of the ascending aorta. Opening of the pericardium revealed normal pericardial fluid and no evidence of injury to the surface of the heart. The patient was placed on cardiopulmonary bypass after establishment of ascending aortic and bicaval cannulation. The heart was arrested with cold blood cardioplegia given via the aortic root. The right atrium was opened, and after suctioning of bright red blood, a 1.5-cm-diameter secundum-type atrial septal defect was repaired with a running 4-0 polypropylene suture. The right atrium was then closed and the ascending aorta was opened obliquely. A small tissue fragment was extracted from the noncoronary cusp of the aortic valve which, on inspection, revealed a single shotgun pellet within the surrounding soft tissue. The aortotomy was closed and the patient was successfully weaned from cardiopulmonary bypass. The patient made an uneventful recovery and was discharged home on the third postoperative day with no left hand weakness.
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Comment
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Embolization of projectiles after penetrating trauma is an infrequent occurrence. The first report of a bullet embolus is credited to Davis, who in 1834 described a case of a young boy struck with a wooden missile fragment that migrated to his right ventricle [1]. Rich and associates [2] examined 7,500 cases of vascular injury during the Vietnam war and could find only 22 cases (0.3%) of missile emboli. Reports of embolization of shotgun pellets are more scarce than for larger projectiles. In a recent review, only 28 cases of shotgun pellet emboli have been described since 1960 [1].
Even more unusual than the above is the situation where a projectile embolizes paradoxically from the venous to the arterial circulation. This may occur via one of three routes. The first involves erosion of the missile across the interatrial or interventricular septum in a patient with a direct projectile injury to the heart [3]. A second route of paradoxical embolization occurs when the projectile erodes across blood vessels from the venous to the arterial circulation [4]. A third possible route for paradoxical embolization occurs when the projectile passes across a congenital cardiac defect. The first such description came from Specht in 1917 [5]. Since that time, only 3 more cases of paradoxical embolus by this mechanism have been reported, and in only 1 of these [6] was a patent foramen ovale actually demonstrated. The present report documents the fifth case in the past 80 years of embolism of a projectile from a venous site across an intracardiac defect to the arterial circulation, and is unusual in that the projectile was a shotgun pellet.
Perhaps the most unusual aspect of this case relates to the retention of the shotgun pellet in the noncoronary sinus of the aortic valve. The pellet, encased in a small amount of soft tissue, was not held fixed within the sinus, and yet it did not embolize distally. This occurrence undoubtedly reflects containment of the pellet by the flow vortex created within the sinus of Valsalva during systole. Although the turbulent flow patterns within the aortic valve sinuses have been well studied [7], there is little information on prevention of distal embolism of particulate matter by these phenomena. In addition, it was indeed fortunate for the patient that the pellet was not contained within the right or left coronary sinus, with its attendant risk of embolization down a coronary artery [8].
Paradoxical bullet embolus is a very rare occurrence, which can be associated with considerable diagnostic confusion. A careful evaluation of the patient’s injuries and a high level of suspicion are required for the successful identification and management of this condition.
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References
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- Yoshioka H., Seibel R.W., Pillai K., Luchette F.A. Shotgun wounds and pellet emboli: case reports and review of the literature. J Trauma 1995;39:596-601.[Medline]
- Rich N.M., Collins G.J., Andersen C.A., McDonald P.T., Kozloff L., Ricotta J.J. Missile emboli. J Trauma 1978;18:236-239.[Medline]
- Neerken A.J., Clement F.L. Air-rifle wound of the heart with embolization. JAMA 1964;189:579-580.
- Lam C.R., McIntyre R. Air-pistol injury of pulmonary artery and aorta. J Thorac Cardiovasc Surg 1970;59:729-732.[Medline]
- Specht V.O. Granatsplitter im linken Ventrikel nach Verletzung der Vena femoralis. Munch Med Wochenschr 1917;27:892-894.
- Schurr M., McCord S., Croce M. Paradoxical bullet embolism: case report and literature review. J Trauma 1996;40:1034-1036.[Medline]
- Peacock J.A. An in vitro study of the onset of turbulence in the sinus of Valsalva. Circ Res 1990;67:448-460.[Abstract/Free Full Text]
- Hopkins H.R., Pecirep D.P. Bullet embolization to a coronary artery. Ann Thorac Surg 1993;56:370-372.[Abstract]
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Abstract
Introduction
