Ann Thorac Surg 2000;69:1594-1596
© 2000 The Society of Thoracic Surgeons
Case reports
Pseudoaneurysm of the outflow graft in a patient with novacor N100 LVAD system
Christoph Knosalla, MDa,
Yu-guo Weng, MDa,
Semih Buz, MDa,
Matthias Loebe, MD, PhDa,
Roland Hetzer, MD, PhDa
a Deutsches Herzzentrum Berlin, Berlin, Germany
Address reprint requests to Dr Knosalla, Abteilung für Herz-, Thorax- und Gefäßchirurgie, Deutsches Herzzentrum Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany
e-mail: knosalla{at}dhzb.de
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Abstract
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Six months after implantation of a wearable Novacor N100 left ventricular assist device, a 47-year-old patient developed a swelling that overlay the body of sternum. Computed tomographic scan of the chest revealed a pseudoaneurysm of the Novacor outflow graft. The patient was taken back to surgery and the diagnosis was confirmed at operation. Repair was performed by direct sutures via right anterolateral thoracotomy, under deep hypothermia and low flow technique. The postoperative course was uneventful.
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Introduction
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Implantable left ventricular assist devices (LVAD) are increasingly used as a bridge to heart transplantation [1, 2], myocardial recovery, or even as an alternative to transplantation [3]. Although overall results are encouraging, thromboembolic events, bleeding complications, and right heart failure, still cause significant morbidity and mortality [4]. This report describes an unusual and previously unreported complication, that of a pseudoaneurysm of the outflow graft in a patient with a wearable Novacor N 100 LVAD (Baxter Healthcare Corp, Oakland, CA).
A 47-year-old man with ischemic cardiomyopathy had been evaluated for heart transplantation. At this time, his blood pressure was at 90/60 mmHg and the heart rate at 86 beats/min. The cardiac index was at 1.8 l/min/m2 and the pulmonary wedge pressure was 17 mmHg. The VO2max was measured at 9.5 ml/kg/min. Transthoracic echocardiography showed grade 1 mitral valve regurgitation and global biventricular hypokinesia with a left ventricular ejection fraction of 25%. The patient was placed on the heart transplantation waiting list. However, 10 months later, acute abdominal pain necessitated laparotomy for appendectomy and resection of a bleeding Meckel’s diverticulum. Postoperatively, the patient had cardiac decompensation and was resuscitated for ventricular fibrillation. He was transferred to our institution. Since the hemodynamic situation deteriorated, despite high doses of catecholamines and the implantation of an intraaortic balloon pump, a Novacor N100 PCq LVAD (Novacor Division, Baxter Healthcare Corp, Oakland, CA) was implanted on an emergency basis in the beating heart in the preperitoneal position under cardiopulmonary bypass and moderate hypothermia.
After the operation, the patient recovered slowly. He was extubated on postoperative day 6 and mobilized. Anticoagulation treatment consisted of coumadin, aspirin, and dipyridamole after all drains were removed. On postoperative day 36, small bowel obstruction necessitated relaparotomy.
Six months after LVAD implantation, the patient was discharged home. However, 2 weeks later, the patient was readmitted for diarrhea and dehydration. Physical examination at readmission revealed a pulsatile swelling that overlay the body of sternum (Fig 1). Computed tomography of the chest with contrast enhancement at this time showed a pseudoaneurysm, which arose from the anterior aspect of the outflow graft and was in direct contact with a sternum wire (Fig 2). There was no evidence of systemic infection.
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Fig 2. Computed tomographic scan of the chest with contrast enhancement revealed a pseudoaneurysm on the anterior aspect of the left ventricular assist device (LVAD) outflow graft in direct contact with a sternum wire.
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The patient was scheduled for immediate surgery. Cardiopulmonary bypass was instituted through femoro-femoral cannulation, and the patient’s core temperature was cooled down to 18°C. The pseudoaneurysm was approached through a right anterolateral thoracotomy in the fourth intercostal space. When the body temperature of 18°C was reached, the flow of cardiopulmonary bypass was reduced to 0.5 l/min. The assist device was stopped with a single stroke every 20 seconds. The aneurysm was entered and the sternum wire removed. The prosthesis showed a small perforation (Fig 3), which was closed by direct sutures with 4-0 polypropylene. Three other sternum wires, which were in direct contact with the prosthesis, were also removed. At each of them, small bleeding perforations of the prosthesis were found. All were repaired by direct sutures. The sternum was closed with 1-0 polydioxanon sutures.
The patient recovered well after surgery and was discharged 2 weeks later. Two months after resection of the pseudoaneurysm, the patient is well. Follow-up computed tomographic scan revealed no signs of aneurysm recurrence.
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Comment
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This report illustrates an unusual complication after implantation of a wearable left ventricular assist device, that of a pseudoaneurysm of the outflow graft, which penetrated the body of sternum. The pseudoaneurysm developed in contact with a sternum wire, which had eroded the prosthesis leading to chronic local bleeding. A pseudoaneurysm developed, which finally eroded and penetrated the sternum. In the Novacor LVAD system, only the valved part of the outflow prosthesis has a metal cage. The pseudoaneurysm occurred on the uncovered part of the outflow graft. This complication might be prevented by caging the entire retrosternal part of the outflow-prosthesis or by guiding the graft from the pump to the ascending aorta through the right pleura. However, this may make the explanation of the device more difficult at the time of transplantation due to adhesions with the lung.
The pseudoaneurysm was approached through a right anterolateral thoracotomy in the fourth intercostal space. This access provides excellent exposition of the middle part of the outflow graft and avoids repeat median sternotomy. By using deep hypothermia with low flow technique, the pseudoeneurysm was easily resected without clamping the outflow graft and without the risk of air embolism.
In conclusion, pseudoaneurysm formation at the outflow conduit is an unusual but life-threatening complication after implantation of wearable LVAD. Deep hypothermia with low flow technique is a safe approach for repairing the defect.
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Acknowledgments
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We are grateful for editorial assistance from Tonie Derwent.
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References
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Hunt S., Frazier O.H., Myers T.J. Mechanical circulatory support and cardiac transplantation. Circulation 1998;97:2079-2090.[Free Full Text]
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Loebe M., Hennig E., Müller J., et al. Long-term mechanical circulatory support as a bridge to transplantation for recovery from cardiomyopathy and for permanent replacement. Eur J Cardiothorac Surg 1997;11:11-24.
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Hetzer R., Müller J., Weng Y., Wallukat G., Spiegelsberger S., Loebe M. Cardiac recovery in dilated cardiomyopathy by unloading with a left ventricular assist device. Ann Thorac Surg 1999;68:742-749.[Abstract/Free Full Text]
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El-Banayosy A., Deng M., Loisance D.Y., et al. The European experience of Novacor left ventricular assist (LVAS) therapy as a bridge to transplant. Eur J Cardiothorac Surg 1999;15:835-841.[Abstract/Free Full Text]
Accepted for publication November 12, 1999.
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