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Ann Thorac Surg 1999;68:105-111
© 1999 The Society of Thoracic Surgeons
a Division of Cardiac Surgery "Ch. Dubost" Center, IRCCS Policlinico S. Matteo, University of Pavia, Pavia, Italy
Address reprint requests to Dr Rinaldi, Division of Cardiac Surgery, IRCCS Policlinico S. Matteo, Piazza Golgi 4, 27100 Pavia, Italy
e-mail: m.rinaldi{at}smatteo.pv.it
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Abstract |
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Methods. Of the 442 patients having orthotopic heart transplantation and the 11 patients having heterotopic heart transplantation at our center, 9 (2%) sustained complications involving the thoracic aorta. These 9 patients were divided into four groups according to the aortic disease: acute aortic rupture (2 patients); infective pseudoaneurysm (3 patients); true aneurysm and dissection of native aorta (2 patients); and aortic dissection after heterotopic heart transplantation (2 patients). Surgical intervention was undertaken in 8.
Results. Five (83%) of 6 patients who underwent surgical treatment for noninfective complications survived the operation, and 4 are long-term survivors. One patient who underwent a Bentall procedure 7
years after heterotopic heart transplantation died in the perioperative period of low-output syndrome secondary to underestimated chronic rejection of the graft. One patient with pseudoaneurysm survives without surgical treatment but died several years later of cardiac arrest due to chronic rejection. Both patients operated on for evolving infective pseudoaneurysm died in the perioperative period.
Conclusions. Infective pseudoaneurysms of the aortic anastomosis are associated with a significant mortality. In noninfective complications, an aggressive surgical approach offers good long-term results. The possibility of retransplantation in spite of complex surgical repair should be considered in the late follow-up after heart transplantation, due to the increasing incidence of chronic rejection.
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Introduction |
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Few reports deal with problems regarding the aortic anastomosis, and the majority of these refer exclusively to infective aortic complications [9–12]. In patients who have had heart transplantation, potential complication areas include the anastomotically sited aortic root, the native ascending aorta, and the native thoracic descending aorta for various reasons. In many cases, because of differences in aortic sclerosis, there could be a compliance mismatch between the donor aorta (D-AO) and the recipient aorta (R-AO) that would create a site of systolic stress. In patients with mediastinitis with inflammatory edema of the tissues, pressure stress favors the formation of pseudoaneurysms at the anastomoses. Hypertensive episodes soon after the operation can partially disrupt the anastomosis. Systemic hypertension consequent to immunosuppression treatment can cause true aneurysms or dissection at any level of the aorta. In heterotopic heart transplantation, native aortic dissection has been reported at the site of anastomosis; compliance mismatch and flow turbulence can contribute to this phenomenon [13].
The aim of this study was to analyze the various types of aortic complications encountered in our series of heart transplantations and to discuss etiology, diagnostic approach, and modes of treatment.
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Patients and methods |
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TopAbstractIntroductionPatients and methodsCommentReferences |
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Orthotopic transplantation was performed in accordance with the surgical technique described by Lower and Shumway [1]. In the last 38 procedures, separate caval anastomoses were performed. Heterotopic transplantation was accomplished according to the technique of Novitzky and colleagues [14]. The only difference was direct terminolateral anastomosis of the two superior venae cavae. The atrial anastomosis was performed with 3-0 Prolene (Ethicon), whereas the pulmonary and aortic anastomoses were done with a running suture of 4-0 Prolene.
Immunosuppression was based on cyclosporine, azathioprine, steroids, and a 5 to 7 day course of lympholytic therapy with antithymocyte globulin. Rejection was monitored by endomyocardial biopsies, and rejection episodes of grade 3A or higher were treated with a pulsed dose of methylprednisolone. Antibiotic prophylaxis was based on a 2-day course of intravenous cefazolin sodium. Thereafter, episodes of infection were treated according to the cultures.
Aortic complications occurred in 9 (2%) of the 453 patients having transplantations. These 9 patients were divided into four groups according to the aortic disease. Patient data and type of aortic involvement are summarized in Table 1.
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Patient 1
A 45-year-old man underwent heart transplantation for ischemic heart disease. The donor was a 40-year-old man with a normal ascending aorta. The R-AO appeared to be extensively atheromatous, partially calcified, and 30% wider in diameter than the D-AO. After an uneventful immediate postoperative course, on day 13, the patient experienced an episode of acute hypotension with a short period (2 minutes) of cardiac arrest during deambulation. Echocardiogram showed pericardial effusion, and chest radiography revealed major mediastinal enlargement, although the hemoglobin level was not greatly decreased.
Despite apparent stabilization, on restoration of normal blood pressure, we performed emergency repeat sternotomy. After suction of a large amount of blood from the pericardiomediastinal cavity, a careful check of the suture lines was undertaken. Removal of a clot on the posterior edge of the aortic suture line revealed a leak 2 cm long. With the bleeding site under digital control, cardiopulmonary bypass was instituted, the aorta was cross-clamped, and the heart was arrested with cold cardioplegic solution. The disruption of the aorta was on the donor side. We opened the anastomosis in its entirety, removed all the weak tissue (1 cm on the donor side and 0.5 cm on the recipient side), and redid the anastomosis with a running suture of 4-0 Prolene reinforced on both sides with Teflon felt.
The patient is alive and well 5 years after transplantation.
Patient 2
A 58-year-old man underwent heart transplantation for heart failure caused by massive aortic regurgitation. On day 17, he was found unconscious in cardiac arrest. Because he was refractory to cardiac resuscitation, surgical reexploration was immediately undertaken. A massive hemopericardium was present, and a leak 3 cm long was found at the aortic suture line on the donor side. Fluid replacement and digital control of the leak allowed restoration of satisfactory cardiac function. Using the Cell Saver device to reduce blood waste, we repaired the leak with five separate stitches reinforced with Teflon pledgets. The operation was technically successful, but the patient never recovered cerebral function and died 6 months later in a rehabilitation center.
Aortic pseudoaneurysm and mediastinal infections
Mediastinitis is a rare but troublesome complication after heart transplantation. In our series, 6 patients (1.3%) required mediastinal debridement for infection. The course was uneventful in 3, but in the other 3, the infection caused an aortic complication that eventually led to the death of 2.
Patient 3
A 45-year-old man underwent heart transplantation for dilated cardiomyopathy. On postoperative day 10, he underwent surgical debridement for mediastinitis caused by Staphylococcus aureus. The pericardiomediastinal cavity was carefully cleaned and rinsed with Betadine (povidone-iodine) and vancomycin; the chest was then closed over tubes for continuous irrigation and drainage. A few hours later, massive bleeding required emergency bedside reexploration. After the patient was placed on cardiopulmonary bypass and under cardioplegic arrest, a leak 1.5 cm long in the D-AO was closed with four separate stitches reinforced with pericardial pledgets. The course was uneventful, and the patient was discharged on day 21.
Four months later, the patient complained of chest pain and fever. Thoracic computed tomographic (CT) scan showed a pseudoaneurysm of the ascending aorta. Blood cultures were positive for S aureus; treatment with vancomycin was begun, and the patient underwent replacement of the ascending aorta with a Dacron conduit. Fever, positive blood cultures, and chest pain persisted, and on postoperative day 30, a CT scan revealed recurrence of a giant pseudoaneurysm originating from the proximal anastomosis with the prosthesis and compressing the pulmonary artery (Figs 1, 2). The patient died before the scheduled reoperation could take place.
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On postoperative day 7, 500 mL of pus under pressure was drained from the pericardial cavity. Immediate reexploration revealed the presence of a purulent pericarditis, without involvement of the presternal soft tissue and with normal stability of the sternum. The agent involved was S aureus, probably transmitted from the donor (both patients who received lungs from the same donor in different institutions died of staphylococcal pneumonia and empyema). The infection was treated with continuous irrigation and drainage, in accordance with our protocol. Immunosuppression was reduced (no steroids, azathioprine, 1 mg · kg-1 · d-1; and cyclosporine, 2 to 3 mg · kg-1 · d-1 to obtain a serum trough level of between 80 and 100 ng/mL).
The patient was discharged on day 30 and did well for 11 months. Then accompanied by fever and chest pain, a fistula appeared on the presternal scar. Thoracic CT scan revealed a retrosternal abscess with pericardial effusion without apparent involvement of the aorta. Sternotomy caused massive bleeding, which was digitally controlled during the institution of femoral-femoral cardiopulmonary bypass. The ascending aorta had a 1.5-cm lesion, which was controlled with two stitches reinforced with Teflon pledgets. The patient died of exsanguination a few hours later in the intensive care unit. Postmortem examination revealed multiple small leaks at the aortic suture line along with abscesses and pseudoaneurysms.
Aneurysms and dissections of native aorta
After transplantation in 2 patients, native aorta was involved in a process related to the underlying atherosclerotic disease and to posttransplantation systemic hypertension.
Patient 6
A 45-year-old man with a history of severe dyslipidemia and hypertension complained of acute back pain 36 months after heart transplantation for ischemic heart disease. Thoracic CT scan revealed a type B aortic dissection extending from the left subclavian takeoff to the bifurcation of the abdominal aorta. Because of hematic pleural effusion and persistent pain, surgical intervention with placement of a Dacron tubular prosthesis was performed. The patient is alive and well 98 months after transplantation.
Patient 7
A 59-year-old man with systemic hypertension that was poorly controlled with medical therapy underwent routine echocardiography 18 months after heart transplantation for ischemic heart disease. The ascending aorta was markedly dilated, and CT scan revealed an aneurysm 10 cm in diameter in the native ascending aorta. The diseased aorta was replaced with a Dacron tubular graft. The operation was complicated by methicillin sodium–resistant S aureus bacteremia and mediastinitis. The patient was treated with vancomycin and cotrimoxazole for almost a year, at which point the Dacron graft was replaced with an aortic homograft.
After operation, the patient was kept on a regimen of vancomycin, but 4 months later, percutaneous drainage was performed because of a new mediastinal collection. Blood cultures were consistently positive for S aureus, and the patient was subject to daily fever. Along with vancomycin and Cotrimoxazole, a regimen of Synercid (Quinupristin-Dalfopristin) was started. This combination provided good control of the infection, but sternal osteomyelitis with fistula developed. The patient is alive 44 months after transplantation.
Dissection of native aorta after heterotopic heart transplantation
In 2 (18.2%) of 11 patients who underwent heterotopic heart transplantation, dissection of the native aorta occurred long after the operation.
Patient 8
A 52-year-old man underwent heterotopic heart transplantation in association with resection of a huge left ventricular aneurysm. After a 29-month normal postoperative course, rapid onset of congestive heart failure prompted thorough reevaluation of the patient. Chest roentgenograms showed mediastinal enlargement, an endomyocardial biopsy was negative, and CT scan revealed the presence of a type A dissection of the native aorta with aortic incompetence and distal extension into the Transverse arch. The intimal tear was identified as corresponding to the aortic anastomosis. The echocardiogram revealed involvement of the incompetent aorta, the failing left ventricle, the common left atrium, the donor left ventricle, and the donor aorta. This induced congestive heart failure. A Bentall procedure was performed, and the patient is doing well 55 months after the operation.
Patient 9
A 53-year-old man underwent heterotopic heart transplantation because of dilated cardiomyopathy. He had a normal postoperative course, and then at 91 months, complained of sudden chest pain followed by rapid onset of congestive heart failure. As in patient 8, the underlying disease was a type A dissection of the native aorta with aortic incompetence and distal extension into the entire arch. The graft ejection fraction at angiography was 0.40 and the peripheral arterial coronary distribution was poor, without major stenoses. A Bentall procedure was performed, with replacement of the aortic arch. Weaning from cardiopulmonary bypass was extremely difficult, and a satisfactory cardiac output was never achieved, despite the use of an intraaortic balloon pump. The patient died of cardiac insufficiency on postoperative day 3. Histologic study of the graft showed widespread fibrosis and advanced peripheral coronary arterial disease.
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Comment |
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TopAbstractIntroductionPatients and methodsCommentReferences |
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The first group is primary acute aortic rupture. It occurs in the very early phase after transplantation and can be related to weakness of the aortic tissue, technical mistakes, or hypertensive episodes. An elegant explanation of a possible mechanism that predisposes patients to early rupture of the ascending aorta was offered by Wada and associates [12], who stressed the importance of compliance mismatch between D-AO and R-AO. During systole, the aortic wall extends and thus transforms part of the kinetic energy into potential energy. During diastole, this energy is used, and blood is sent ahead in continuous fashion ("Windkessel" function) [15]. Frequently in heart transplantation, there is a marked difference in diameter and compliance between the D-AO and the R-AO. This implies a lack of synchronization between the two aortas. As a consequence, the D-AO tends to increase in diameter thus creating excessive tension at the suture line and a consequent predisposition to rupture. To limit the potential danger of compliance mismatch, the D-AO and R-AO must be carefully aligned and trimmed.
Early aortic rupture is often a dramatic event, but sometimes there is an apparent self-repair, which gives the surgeon a short time in which to intervene. In our patient 1, identification of the bleeding site required digital mobilization of the aorta.
The second group comprises bacterial and mycotic pseudoaneurysms of the ascending aorta and mediastinal infection. Mediastinitis after transplantation is a troublesome event because of the high rate of recurrence and its long-term complications [16]. In our 6 patients with mediastinitis, there were no early postoperative deaths directly related to the infectious process, but in the 4- to 27-month postoperative period, pseudoaneurysm of the aortic wall was diagnosed in 50% of them. The treatment of mediastinal infection varies. Our protocol is based on early debridement, primary closure of the sternum, and continual instillation of povidone-iodine (Betadine), 0.025% in normal saline solution, for a total of 4 to 6 L/d. After 15 to 20 days of treatment, removal of the drains is considered even if cultures of the material drained are positive. In the case of recurrence, partial sternal resection and pectoralis muscle interposition are performed. Antibiotic therapy is administered on the basis of culture results. Immunosuppression is reduced to a minimum: azathioprine is withdrawn, steroids are withdrawn or reduced to 5 mg/d, and cyclosporine is kept at the lowest level permitted by the protocol. In the 6 patients with mediastinitis, drains remained in place for a mean of 14 days (range, 7 to 41 days) and, in the group in whom aortic pseudoaneurysm subsequently developed, drains remained in place for 10, 20, and 41 days. Only in 1 patient were drains removed after cultures were negative.
The best way to treat infective pseudoaneurysms is debated. The few successful cases reported in the literature were treated radically with graft replacement of the diseased aorta [9]. Our experience with the 2 patients surgically treated was disappointing. A different strategy might have given both patients better changes of success. With the benefit of hindsight, in patient 3, we would now replace the ascending aorta with a homologous conduit instead of an artificial graft, as in patient 8, and in patient 5, we would make every attempt to treat the lesion radically instead of limiting intervention to repair of the aortic leak. The conservative choice made in patient 4 was mandatory, given the fact that a further repeat sternotomy would have been extremely difficult and dangerous.
Patients who experience mediastinitis after heart transplantation should be followed up carefully with blood cultures, echocardiogram, thoracic CT scan, and nuclear magnetic resonance imaging. If there is evidence of recurrent mediastinal infection, immediate surgical intervention is indicated. If a pseudoaneurysm is present, it must be resected and the affected aortic segment replaced with a homologous conduit. Postoperative long-term or lifelong antibiotic therapy is mandatory, depending on blood cultures and sensitivity [16].
The third group is true aneurysm and dissection of the native aorta. Atherosclerosis can predispose patients to the formation of aneurysms or dissections, especially in the presence of the high systemic pressure that not infrequently occurs after heart transplantation. Both of our patients underwent heart transplantation for ischemic heart disease, and 1 was diabetic before transplantation. In both, immunosuppression therapy caused early hypertension, dyslipidemia, and diabetes, all of which are difficult to control. The prevalence of aneurysm in the ascending aorta is surprisingly low even in the presence of significant risk factors; it must, however, be taken into account, and exploration of the ascending aorta must be included in routine follow-up echocardiography. Because the aortic lesion is almost always the adverse effect of both heart transplantation per se and the necessary immunosuppression therapy, it tends to progress, and surgical treatment is necessary.
The fourth group comprises aortic dissection in heterotopic heart transplantation. Dissection of the native aorta occurred in 2 (18.2%) of the 11 patients who underwent heterotopic heart transplantation. The aortic tear originated at the anastomosis where native aorta is subject to several stress factors resulting from stress on a limited portion of native aorta opposite the anastomosis and, possibly, to discordance of the systolic and diastolic changes in wall tension of the two aortas. The angle of incidence of the D-AO with the R-AO can also play a role in creating wall stress: the sharper the angle, the more linear the flow, and hence, the lower the asymmetric systolic tension on the R-AO becomes. We now consider the aortic anastomosis a critical point of the entire operation, and we pay particular attention to prevent excessive D-AO length and to limit the angle of incidence to a maximum of 45 degrees.
The best surgical approach to this complication is a question for debate. Removal of the native heart with or without insertion of a new graft is an extremely demanding operation, as is the removal of both hearts and the performance of orthotopic heart transplantation. The alternative suggested to the Bentall technique by Yacoub [13] consists of repair of the native aortic valve and replacement of the ascending aorta with a tubular graft. The manifest advantage of this approach lies in its prevention of thromboembolic events.
In conclusion, the site of the aortic anastomosis in heart transplantation deserves particular attention as a potential source of early and late complications. Discrepancy in tissue quality between the D-AO and the R-AO is responsible for a compliance mismatch that causes a difference in wall tension. This in turn acts as a critical stress factor at the anastomosis. In the case of mediastinitis, the aortic suture line is frequently involved in pseudoaneurysm formation. In heterotopic transplantation, the complex play of flow dynamics at the ascending aorta is a potential cause of dissection. After heart transplantation, the entire thoracic aorta is, in many cases, at risk of aneurysm formation or dissection because of the abrupt change in systemic pressure. Even though the prevalence of these complications is limited, the problems with any type of surgical intervention are sufficiently formidable to warrant systematic appraisal of the entire spectrum of aortic complications after heart transplantation.
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Footnotes |
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References |
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TopAbstractIntroductionPatients and methodsCommentReferences |
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This article has been cited by other articles:
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  C Schellemans, W Tack, and M Vanderheyden Acute type A aortic dissection in a cardiac allograft recipient: case report and review of the literature Heart, November 1, 2004; 90(11): 1256 - 1258. [Abstract] [Full Text] [PDF]
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 Y. Naka, N. M. Edwards, and M. C. Oz Novel technique to repair type A acute aortic dissection in patients with a left ventricular assist device Ann. Thorac. Surg., October 1, 2001; 72(4): 1403 - 1404. [Abstract] [Full Text] [PDF]
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T. Omoto, K. Minami, T. Muramatsu, S. Kyo, and R. Korfer Pseudoaneurysm after heart transplantation with history of LVAD driveline infection Ann. Thorac. Surg., July 1, 2001; 72(1): 263 - 264. [Abstract] [Full Text] [PDF]
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