Ann Thorac Surg 2001;72:253-255
© 2001 The Society of Thoracic Surgeons
Case report
Traumatic disruption of the ascending aorta in a child after heart transplant
Gordon A. Cohen, MDa,
Victor T. Tsang, FRCSa,
Robert W.M. Yates, MRCPa,
Martin J. Elliott, FRCSa,
Marc R. de Leval, MDa
a Cardiothoracic Unit, Great Ormond Street Hospital for Children NHS Trust, London, England, UK
Accepted for publication June 16, 2000.
Address reprint requests to Dr Cohen, Great Ormond Street Hospital for Children NHS Trust, Great Ormond St, London WC1N 3JH, England
e-mail: gordon.cohen{at}gosh-tr.nthames.nhs.uk
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Abstract
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We report a traumatic disruption of the ascending aorta in an 8-year-old boy who had undergone orthotopic cardiac transplant at 6.5 years of age for congenital heart block and dilated cardiomyopathy. At presentation his aortic injury was not immediately recognized, but persistence in identifying and confirming a suspicious aortic rupture was lifesaving.
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Introduction
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Traumatic rupture of the thoracic aorta at the level of the ligamentum arteriosum is a well-recognized injury following deceleration-type chest injury. Following certain cardiac surgical procedures, the ligamentum arteriosum may be divided and injury to the aorta may occur in other locations following blunt chest trauma. We report here the case of traumatic disruption of the ascending aorta in a cardiac transplant patient following a motor vehicle accident.
The patient was an 8-year-old boy who was born with congenital heart block and by the age of 5 years he had developed signs of dilated cardiomyopathy despite adequate pacing. At the age of 6.5 years he underwent orthotopic cardiac transplant (bicaval anastomosis) with an uneventful postoperative course. Two months following transplant, intermittent complete atrioventricular block developed in the patient and required a new permanent pacemaker. The etiology of the heart block in the transplanted organ has never been identified. Despite this unusual problem, the child had good graft function and normal exercise tolerance at follow-up 16 months post transplant with a normal echocardiogram.
Two months later, the child was a restrained rear-seat passenger in an automobile that was involved in a head-on collision with another vehicle. At the time of initial presentation to the local hospital, the child was hemodynamically stable and examination demonstrated only minor injuries. Initial chest radiograph was normal. During the following six days the child remained stable, but with a low-grade fever, mild respiratory distress and hypoxia. Transthoracic echocardiogram was reported as normal. Because of ongoing deterioration, he was transferred back to our hospital. A repeat chest radiograph demonstrated a large right pleural effusion. Transthoracic echocardiogram at that time demonstrated good ventricular function, no pericardial effusion, large right pleural effusion, small left pleural effusion and dilated ascending aorta, but no obvious evidence of aortic rupture.
CT scan of the chest (Fig 1) confirmed the right pleural effusion, and there was a circular structure adjacent to the right atrium. Drainage of the right pleural effusion was chylous in nature and resulted in temporary clinical improvement. To clarify the CT images, transesophageal echocardiography was performed (Fig 2). This demonstrated a false aneurysm of the ascending aorta compressing the right atrium and SVC with a wide opening on its posterior aspect just superior to the sino-tubular junction. A cardiac catheter was then performed (Fig 3) confirming the presence of a false aneurysm and excluding distal aortic injury. The child was taken to the operating room for urgent exploration and repair, he was placed on femoral bypass before median sternotomy. Once the chest was entered, a large pseudoaneurysm filled with fresh thrombus was identified and there was a 3 cm disruption in the aortic suture line of the previous transplant anastomosis. The aorta was resected back to healthy tissue both proximal and distal to the disrupted suture line and a 28 mm Hemashield interposition graft was sewn into place. The postoperative course was uneventful and the chylothorax did not recur.
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Fig 1. Axial CT scan with contrast through mid chest region showing right pleural effusion and circular shadow adjacent to right atrium.
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Fig 2. Transesophageal echocardiogram (four chamber view) showing large thrombus (arrowed) within aneurysm (asterisk) partly compressing the right atrium. (LA = left atrium; LV = left ventricle; RA = right atrium, RV = right ventricle).
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Fig 3. Lateral aortogram confirming false aneurysm posteriorly (open arrow). Note large ascending aorta and absence of distal aortic rupture (closed arrow = native aortic root).
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Comment
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Traumatic aortic rupture carries a high morbidity and mortality (14% to 28%) [1]. Aortic rupture is most commonly caused by the unequal rate of horizontal deceleration on different points of the aorta. Eighty percent of all blunt aortic injuries occur at the aortic isthmus.
Nontraumatic disruption of the aortic anastomosis has been reported following heart-lung transplant in the setting of underlying infection with Candida [2]. In this particular patient, the injury was unusual because the site of injury was in the ascending aorta and infection did not play an etiologic role. Charles and colleagues described the case of a traumatic rupture of the ascending aorta and aortic valve in a 56 year-old man following blunt chest trauma sustained in a motor vehicle accident [3]. The classic radiologic sign of traumatic rupture of the aorta, a widened superior mediastinum, was completely absent despite the severe vascular injury which he had sustained. More recently, Dunn and Williams described a patient with an ascending aortic rupture sustained from impact with an air-bag during a motor vehicle accident [4]. Again, the chest radiograph demonstrated a normal mediastinum. In a recent review, Symbas and coworkers reported on three cases of traumatic rupture of the ascending aorta and reported the literature on 17 others. In their review, most of the patients presented with multiple trauma or signs of cardiac tamponade. Six of 14 patients had a normal chest roentgenogram despite the underlying injury [5]. In our patient, every chest radiograph that was taken demonstrated a normal vascular pedicle with no change in the superior mediastinal shadow. Thus, classic imaging techniques may not be sensitive enough to detect this type of injury, and might have contributed to the delay in his diagnosis. As the workup progressed, the presence of a right pleural effusion on both chest roentgenogram and CT scan led to confusion in the diagnosis. When the effusion was aspirated and found to be chylous in nature, the possibility of a lymphatic duct injury was entertained. The transesophageal echocardiogram was the first diagnostic test to clearly demonstrate the injury to the ascending aorta. Because the mechanism of injury this child sustained usually causes injury at the aortic isthmus, an area not well visualized by transesophageal echocardiography, the patient underwent cardiac catheterization. The aortogram excluded a distal aortic transection.
This case represents an unusual decelerating injury to the ascending aorta after heart transplant. It illustrates that the clinical presentation may be itself atypical and persistence in accurately determining the cause of any unusual clinical findings is imperative and may be lifesaving. [6]
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References
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Cowley R.A., Turney S.Z., Hankins J.R., Rodriguez A., Attar S., Shankar B.S. Rupture of the thoracic aorta caused by blunt chest trauma: a fifteen year experience. J Thorac Cardiovasc Surg 1990;100:652-661.[Abstract]
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Dowling R.D., Baladi N., Zenati M., et al. Disruption of the aortic anastomosis after heart-lung transplantation. Ann Thorac Surg 1990;49:118-122.[Abstract]
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Charles K.P., Davidson K.G., Miller H., Caves R.K. Traumatic rupture of the ascending aorta and aortic valve following blunt chest trauma. J Thorac Cardiovasc Surg 1977;73:208-211.[Abstract]
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Dunn J.A., Williams M.G. Occult ascending aortic rupture in the presence of an air bag. Ann Thorac Surg 1996;62:577-578.[Abstract/Free Full Text]
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Symbas P.J., Horsley W.S., Symbas P.N. Rupture of the ascending aorta caused by blunt trauma. Ann Thorac Surg 1998;66:113-117.[Abstract/Free Full Text]
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Treasure T. Imaging the thoracic aorta in the injured patient. Heart 1997;78:207-208.[Free Full Text]
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Abstract
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