Ann Thorac Surg 2005;80:710-712
© 2005 The Society of Thoracic Surgeons
Case report
Traumatic Rupture of a Descending Thoracic Aortic Homograft
Matthias Peltz, MD,
Bernardo A. Sandoval, MD,
Michael E. Jessen, MD
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Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas
Accepted for publication February 10, 2004.
* Address reprint requests to Dr Jessen, Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd, Dallas, TX 75390-8879 (Email: michael.jessen{at}utsouthwestern.edu).
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Abstract
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My colleagues and I report an unusual case of traumatic aortic injury in an 18-year-old woman who had undergone multiple prior surgical procedures for repair of a type B interrupted aortic arch. Her most recent procedure included replacement of the proximal descending thoracic aorta with a 19-mm homograft at age 11 years. Seven years later, she was involved in a motor vehicle collision after a syncopal episode. Imaging studies revealed rupture of the body of the aortic homograft with formation of a pseudoaneurysm. The injury was successfully repaired with a Dacron graft by using hypothermic circulatory arrest.
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Introduction
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Traumatic rupture of the aorta is one of the most common causes of trauma death. Most victims (57% to 85%) die before hospital arrival [1, 2]. Mortality among initial survivors remains substantial; 20% to 44% of patients die from aortic rupture, associated injuries, or other complications [2–4]. Aortic injury among survivors occurs most frequently at the level of the ligamentum arteriosum, although the location among all victims is more variable [1]. Reports of traumatic aortic injury after repair of congenital cardiac or aortic anomalies are rare. This report describes a traumatic aortic rupture within the body of a previously placed descending aortic homograft.
An 18-year-old woman had presented with symptoms of heart failure at 2 weeks of age. Subsequent workup demonstrated a type B interrupted aortic arch and a ventricular septal defect. The patient underwent arch reconstruction with a 7-mm Impra graft (Bard Inc, Murray Hill, NJ) and pulmonary artery banding through a left thoracotomy. She returned to the operating room 4 months later for closure of the ventral septal defect, closure of a small atrial septal defect, resection of subaortic stenosis, and pulmonary artery debanding by a median sternotomy. This procedure was complicated by complete heart block, which was treated by placement of an epicardial pacemaker. She required repeat resection of subaortic stenosis and aortic valvuloplasty at age 4 years. At age 11, a significant gradient was measured across her aortic arch conduit, and she underwent replacement of the graft and proximal descending aorta with a 19-mm homograft through a left thoracotomy.
The patient did well until 7 years later, when she experienced a syncopal episode while driving that led to a motor vehicle collision. On hospital arrival, initial evaluation revealed an altered neurologic status and facial contusions. The initial computed tomographic scan of the head demonstrated a small tentorial subarachnoid hemorrhage that was absent on follow-up studies. Chest radiographs were unrevealing. She was intubated for airway protection until her neurologic status improved. Her hemodynamics remained stable (heart rate, 50 to 60 bpm; mean arterial blood pressure, 60 to 65 mm Hg). She was subsequently evaluated with an electrophysiology study, cardiac catheterization, and a computed tomographic scan of the chest. These studies demonstrated a 2-cm pseudoaneurysm of the proximal descending thoracic aorta arising from the body of the homograft (Figs 1A, 1B). She was referred for surgical repair.
At operation, general anesthesia was administered with a double-lumen endotracheal tube. The left common femoral vein was exposed. The chest was entered through the fourth intercostal space. After extensive adhesiolysis, the descending aorta was exposed. The site of the pseudoaneurysm was densely adherent to the lung and was not disturbed. Because of extensive adhesions, it was believed that the aorta could not be safely clamped proximal to the injury. After heparinization, cardiopulmonary bypass was initiated. Venous inflow was supplied from a Biomedicus cannula (Medtronic-Biomedicus Inc, Eden Prairie, MN) inserted through the right common femoral vein and advanced to the right atrium. Arterial return was directed through an angle-tipped cannula positioned in the distal descending thoracic aorta. The patient was systemically cooled to 16°C. The descending aorta was clamped above the aortic cannula, and flow of 500 to 1,000 mL/min was maintained to the lower body during 38 minutes of deep hypothermic circulatory arrest. The lung was freed from the severely calcified aortic homograft, and a 1.5-cm transverse laceration was identified in the midbody of the homograft. The calcified ("eggshell") homograft was removed and replaced with an 18-mm Hemashield graft (Boston Scientific, Wayne, NJ). The patient was rewarmed and weaned from cardiopulmonary bypass without difficulty. She was extubated on postoperative day 2 but required considerable treatment for left lung atelectasis. This gradually improved, and she was discharged on postoperative day 18. She remains well at 4-year follow-up with no signs of recurrent aortic pathology.
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Comment
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Traumatic aortic rupture from blunt trauma is usually related to rapid deceleration injury. The typical location of the injury in patients who survive the initial event is at the level of the ligamentum arteriosum. After previous cardiothoracic procedures, blunt aortic disruption may occur in less common locations, such as the as ascending aorta or along previous suture lines, presumably because of altered aortic fixation. Cohen and colleagues [5] reported a traumatic ascending aortic disruption in a child who had previously undergone cardiac transplantation.
Our case is unusual for several reasons. First, initial evaluation did not demonstrate mediastinal widening on chest roentgenogram. This could be related to postoperative changes that may limit extravasation of blood or make interpretation difficult. However, even without prior cardiac operations, chest radiographs are negative in a small percentage of traumatic aortic disruptions [4]. The location of the tear was also remarkable because it did not involve a suture line between the native aorta and the graft, as might be expected in a patient with prior aortic operation. Instead, the tear occurred within the homograft itself.
Experimental studies have reported immune-mediated wall degeneration in allograft conduits [6]. Intimal fracture from rapid graft thawing or conduit handling before implantation has been suggested as the cause of an ascending aortic dissection after homograft placement [7]. The degree of calcification encountered in this case during homograft removal supports the concept that a similar form of chronic graft deterioration may have contributed to the observed disruption.
In summary, this report documents a traumatic aortic disruption in a patient with a prior homograft replacement of the aortic arch and descending thoracic aorta. The clinical presentation of these patients may be atypical, and a high index of suspicion is required for diagnosis. The presence of a previous homograft warrants careful evaluation to exclude injury either in the native aorta or within the graft itself. Once this problem is identified, successful repair is possible but may require modification of standard techniques.
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References
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- Burkhart HM, Gomez GA, Jacobson LE, Pless JE, Broadie TA. Fatal blunt aortic injuriesa review of 242 autopsy cases. J Trauma 2001;50:113-115.[Medline]
- Fabian TC, Richardson JD, Croce MA, et al. Prospective study of blunt aortic injurymulticenter trial of the American Association for the Surgery of Trauma. J Trauma 1997;42:374-383.[Medline]
- Cowley RA, Turney SZ, Hankins JR, Rodriguez A, Attar S, Shankar BS. Rupture of thoracic aorta caused by blunt traumaA fifteen-year experience. J Thorac Cardiavasc Surg 1990;100:652-661.[Abstract]
- Hunt JP, Baker CC, Lentz CW, et al. Thoracic aorta injuriesmanagement and outcome of 144 patients. J Trauma 1996;40:547-556.[Medline]
- Cohen GA, Tsang VT, Yates RWM, Elliott MJ, de Leval MR. Traumatic disruption of the ascending aorta in a child after heart transplant Ann Thorac Surg 2001;72:253-255.[Abstract/Free Full Text]
- Neves JP, Gulbenkian S, Ramos T, et al. Mechanisms underlying degeneration of cryopreserved vascular homografts J Thorac Cardiovasc Surg 1997;113:1014-1021.[Abstract/Free Full Text]
- Smith JA, McKenzie TC, Davis BB. Dissection of an allograft ascending aorta after aortic root replacement Ann Thorac Surg 1996;61:1011-1012.[Abstract/Free Full Text]
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Abstract
Introduction
