Ann Thorac Surg 1997;64:845-847
© 1997 The Society of Thoracic Surgeons
Case Report
Enlarging Mediastinal Mass After Cardiac Transplantation
Samuel Weinstein, MD,
Karen D. Horvath, MD,
Benjamin E. Romney, MD,
Robert E. Michler, MD
Division of Cardiothoracic Surgery, Columbia Presbyterian Medical Center, New York, New York
Accepted for publication April 23, 1997.
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Abstract
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Pseudoaneurysms of the ascending aorta are a rare but potentially fatal complication of cardiac surgical procedures. There are few reports of pseudoaneurysm formation after cardiac transplantation, and previously reported cases involve mycotic aneurysmal tissue. This case report describes a 53-year-old man in whom a noninfectious aneurysm of the ascending aorta developed after cardiac transplantation.
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Introduction
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Most pseudoaneurysms after cardiac operations have been associated with coronary artery bypass grafting or aortic valve operations. They are primarily mycotic in origin. Before the discovery of antibiotics, pseudoaneurysms of the ascending aorta were usually associated with endocarditis of the aortic valve [1]. Today, pseudoaneurysms can form after any cardiovascular procedure, and usually occur at anastomotic suture lines, areas of technical defects, needle holes, and vent sites. Preoperative diagnosis can be made by aortography, computed tomagraphic scan, or magnetic resonance imaging. This report describes the diagnosis and management of an enlarging, noninfectious mediastinal aneurysm in a patient after cardiac transplantation.
A 53-year-old man with a history of atrial fibrillation and biventricular failure secondary to an idiopathic dilated cardiomyopathy underwent left ventricular assist device (Thermo Cardiosystems Inc, Woburn, MA) placement in January 1995. A right upper lobectomy for a nonhealing lung abscess was performed 3 months later in preparation for his transplantation. On July 5, 1995, he underwent explantation of the mechanical assist device and orthotopic heart transplantation. The procedure was complicated by bleeding at the pulmonary artery anastomosis, which was controlled with a pericardial pledget. He had moderate bleeding from his chest tubes the first postoperative day, but otherwise recovered uneventfully.
Within 3 weeks of the operation a chest roentgenogram demonstrated a nodular density in the region of the resected rib from the patient's previous thoracotomy (Fig 1
). A computed tomographic scan done to evaluate this nodule found it to be a solitary cavitary lesion. Incidentally, a region of high attenuation consistent with a hematoma was found compressing the right ventricular outflow tract and pulmonary arteries. Transesophageal echocardiography at that time had normal results. At the time of the patient's first cardiac biopsy and catheterization, pulmonary angiography was performed, which did not demonstrate extravasation of contrast, mass compression, or gradient across the pulmonary artery. The patient was afebrile, with a normal white blood cell count, and denied chills, shortness of breath, or chest pain.
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Fig 1. . Posteroanterior view of the chest demonstrates a quarter-sized nodule in the right chest. Note the size of the mediastinum.
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Chest roentgenograms taken over the next 4 months showed resolution of the nodule, but an increasing mediastinum (Fig 2). A repeat computed tomographic scan 4 months postoperatively demonstrated a 7.5 x 8.2 x 8.5-cm mass along the pulmonary artery with a heterogeneous pattern suggesting aneurysm (Fig 3). Magnetic resonance imaging revealed a 7.5-cm mass, consistent with a partially thrombosed pseudoaneurysm, distorting the right ventricular outflow tract–main pulmonary artery junction (Fig 4). Pulmonary artery aneurysm was suggested as the diagnosis because of the history of bleeding at the pulmonary arterial anastomosis at the time of the transplantation and because of the appearance of the mass on radiologic studies. Because the size of the aneurysm was enlarging, surgical repair was recommended and the patient concurred. Pulmonary angiography was not performed because the patient's creatinine level was 3.0 mg/dL.
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Fig 2. . Widened mediastinum in the region of the main pulmonary artery seen on plain chest roentgenogram several months later.
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Fig 3. . Noncontrast transaxial computed tomographic scan shows relatively high attenuation material consistent with blood or clot in the transverse sinus of the pericardium. Main pulmonary–right pulmonary artery junction is occupied by the abnormal material.
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Fig 4. . Oblique sagittal view magnetic resonance image shows compression of the main pulmonary artery and right ventricular outflow tract by a mass with mixed signal intensity compatible with low-velocity blood and thrombus.
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Intraoperative transesophageal echocardiography appeared to show a connection of the aneurysm with the aorta, but a large, central aortopulmonary arterial fistula seemed unlikely in the absence of symptoms. The chest was reopened through the sternum and moderate adhesions in the pericardial space were taken down. A large mass extending between the aortopulmonary window and the left hilum of the lung was encountered. The patient was placed on bypass in an attempt to decompress the aneurysm, and the dissection was begun from inside the pericardial well. Tissue around the mass was extremely dense, and the planes were not obvious. We elected to enter the aneurysm directly, with the control of cardiopulmonary bypass. As thrombus and fresh clot were removed from within the sac, bright red blood under pressure appeared at the inferior, medial portion of the aneurysm adjacent to the aorta. This was controlled with digital pressure while further inspection from inside the aneurysm showed a connection not to the low-pressure pulmonary artery, but to the ascending aorta. Further dissection without control of the aorta would have resulted in uncontrollable hemorrhage, and the patient was cooled to 20°C in preparation for circulatory arrest. Once the circulation was stopped, the defect could be clearly seen on the posterior aspect of the ascending aorta, separate and proximal to the aortic suture line. A bovine pericardial patch was used for the repair, sewn with 4-0 Prolene (Ethicon, Somerville, NJ). Circulatory arrest was discontinued, and the patient was rewarmed and weaned from cardiopulmonary bypass. He recovered from the operation uneventfully and went home on postoperative day 6.
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Comment
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A pseudoaneurysm results when bleeding from an injury to the vessel wall is contained by the remaining layers of the vessel wall, or surrounding tissues. The hematoma that forms is covered by a layer of tissue, or neointima. This is distinct from a true aneurysm, where there is also a widening of the aorta but all three of the vascular layers are involved in the dilatation.
Aortic pseudoaneurysms may present as a pulsatile suprasternal mass, myocardial ischemia due to compression of grafts, chest pain, compression symptoms of dysphagia or stridor, asymptotically, or with signs of septicemia if a mycotic pseudoaneurysm is encountered. Ruptured mycotic aneurysm of the aorta was reported as the cause of 3% of the late deaths in a series of 1,000 consecutive bypass patients [2].
Chest roentgenography, computed tomography, magnetic resonance imaging, and aortography can all aid in the diagnosis preoperatively [1]. Computed tomographic scan can also give additional information such as the state of the surrounding tissues (infection), abscess formation, effusions, and sternal osteomyelitis. The anatomy seen on radiologic studies may influence the operative approach. Although it did not affect this patient, if the aneurysm is seen adjacent to the sternum on a computed tomographic scan preoperatively, initial femoral bypass may be indicated to decompress the mass before opening the sternum. In our patient, there appeared to be room under the sternum to obviate the need for femoral bypass before sternotomy, but the radiologic evidence of adherence to the hilum contributed to our abandoning aggressive dissection early and opening the aneurysm directly.
Pseudoaneurysms after organ transplantation are rare. Eleven of 1,211 liver transplants, 3 of 1,162 renal transplants and 1 of 14 pancreas transplants patients had been reported as developing a vascular pseudoaneurysm as of 1988 [3]. The causes reported included anastomotic defects, needle holes from venting, biopsies, and infection [1, 4, 5]. The occurrence of a pseudoaneurysm after cardiac transplantation is rare, with only 5 cases of mycotic aneurysms reported in more than 5,000 cases performed [4–7]. The defect in our patient appeared on the posterior wall, proximal to and separate from the suture line. The most likely cause of this patient's injury was a puncture with the cardioplegia needle placed on the anterior surface of the aortic wall and penetrating the back wall at the time of the organ harvest, or an injury to the aorta at the time of transplantation.
This report demonstrates that noninfected pseudoaneurysm of the ascending aorta can occur after cardiac transplantation. One should respect the donor as well as recipient aorta, to avoid injuries that might ultimately lead to false aneurysm formation. Operative management requires a stepwise approach to aneurysm control, or entry with early establishment of cardiopulmonary bypass and possible use of circulatory arrest.
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Footnotes
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Address reprint requests to Dr Michler, Columbia Presbyterian Medical Center, 177 Fort Washington Ave, Milstein Hospital Bldg, Rm 7-435, New York, NY 10032.
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References
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- Sullivan KL, Seiner RM, Stanton SN, Griska L, Meister SG. Pseudoaneurysm of the ascending aorta following cardiac surgery. Chest 1988;92:138–43.
- Keon WJ, Bedard P, Akyureki Y, Brais M. Causes of death in aortocoronary bypass surgery: experience with 1,000 patients. Ann Thorac Surg 1977;23:357–60.[Abstract]
- Tobben PJ, Zajko AB, Sumkin JH, et al. Pseudoaneurysms complicating organ transplantation: roles of CT, duplex sonography and angiography. Radiology 1988;169:65–7.[Abstract/Free Full Text]
- Taylor DO, Rehr RB, Thompson JA, Vetrovec G, Tatum JL. Aortic pseudoaneurysm occurring after cardiac transplantation. Am Heart J 1990;120:1222–5.[Medline]
- McGiffin DC, Galbraith AJ, McCarthy JB, Tesar PJ. Mycotic false aneurysm of the aortic suture line after heart transplantation. J Heart Lung Transplant 1994;13:926–8.[Medline]
- Palac RT, Strausbaugh LJ, Ruza A, Floten HS. An unusual complication of cardiac transplantation—infected aortic pseudoaneurysm. Ann Thorac Surg 1991;51:479–81.[Abstract]
- Byl B, Jacobs F, Antoine M, et al. Mediastinitis caused by Aspergillus fumigatus with ruptured aortic pseudoaneurysm in a heart transplant recipient: case study. Heart Lung 1993;22:145–7.[Medline]
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Abstract
Introduction
