Ann Thorac Surg 2006;82:1527-1529
© 2006 The Society of Thoracic Surgeons
Case Reports
Leakage of the Arterial Prosthesis of an Impella RVAD
Hendrik T. Tevaearai, MDa,*,
Juerg Schmidli, MDa,
Paul Mohacsi, MDb,
Hans-Ulrich Rothen, MDc,
Friedrich S. Eckstein, MDa,
Thierry P. Carrel, MDa
a Clinic for Cardiovascular Surgery, University Hospital, Bern, Switzerland
b Clinic of Cardiology, University Hospital, Bern, Switzerland
c Intensive Care Unit, University Hospital, Bern, Switzerland
Accepted for publication February 3, 2006.
* Address correspondence to Dr Tevaearai, Clinic for Cardiovascular Surgery, University Hospital, Freiburgstrasse, Bern, CH-3010 Switzerland (Email: hendrik.tevaearai{at}insel.ch).
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Abstract
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Seromas occurring around a vascular graft are a rare complication. We report a life-threatening plasma leakage that occurred through the polytetrafluoroethylene vascular prosthesis of an Impella right ventricular assist device (Impella RD [Impella Cardiosystems GmbH, Aachen, Germany]) implanted in a 62-year-old patient with acute right ventricular failure after cardiac transplantation. The leakage became progressively massive. Weaning the patient from the right ventricular assist device was not possible. The prosthesis was thus wrapped within a pericardial patch to contain the leakage. Three days later the patient could be successfully weaned and the pump was removed. The clinical evolution was favorable.
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Introduction
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Technical complications of assist devices have been observed with a decreased incidence in recent years. The Impella right ventricular assist device (RVAD) (Impella RD [Impella Cardiosystems GmbH, Aachen, Germany]) is a miniaturized axial pump specially designed to unload the right ventricle; it consists of a right atrial inflow access and an outflow conduit connected to the pulmonary arterial trunk. The later component of the system is actually a ring-reinforced polytetrafluoroethylene (PTFE) vascular prosthesis. Perigraft seroma is a known complication of arterial artificial prosthesis and may sporadically appear, especially around the PTFE prosthesis [1–6]. We report an isolated case of a massive leakage of the PTFE arterial prosthesis of an Impella RD RVAD (Impella Cardiosystems GmbH) observed after implantation because of a cardiac graft failure.
A 62-year-old woman with blood group A+, suffering from a chronic atrial fibrillation as well as a post-rheumatic valvular and dilated cardiomyopathy that already required a combined mitral and aortic valve replacement more than 10 years earlier was referred to our hospital with a decompensated left ventricular failure (New York Heart Association functional class III; ejection fraction, 15%; left ventricular end-diastolic diameter [LVEDD], 63 mm) and chronic renal insufficiency (creatinine clearance, 33 mL/min). After evaluation the patient was put on the transplantation list. Only 5 days later an appropriate and matching cardiac graft was offered. Due to a respiratory infection with a C reactive protein (CRP) value of 210 mg/L, preoperative antibiotic treatment (Cefepime, Bristol-Myers Squibb, Baar, Switzerland) was initiated. The transplantation was performed using a standard bi-caval technique. Graft cold ischemic time was 133 minutes. After aortic de-clamping, the heart immediately returned to sinus rhythm and was paced AAI at 90 per minute. Because of the initial right ventricular weakness, reperfusion was prolonged until stabilization of the hemodynamics. The patient was then successfully weaned from extracorporeal circulation (ECC) (total ECC time, 104 minutes), the sternum was closed, and the patient was transferred to the intensive care unit with a moderate regimen of catecholamines. Six hours later she progressively became hemodynamically unstable. Transesophageal echocardiography excluded a cardiac tamponade but showed a predominantly right ventricular failure. Even though the sternotomy was reopened and the catecholamine regimen was maximizing, the right ventricular insufficiency could not be improved. Thus it was decided to implant an Impella RD RVAD (Impella Cardiosystems GmbH). The pump was implanted on a beating heart between the right atria and the pulmonary artery. Importantly the pump was not re-sterilized and the PTFE component had not been excessively manipulated during the procedure. Hemodynamics improved immediately. The thorax was left open, and 48 hours later the sternotomy was revised and new povidone-iodine impregnated gauzes were used to cover the wound. The conditions of the patient was stable and the Impella RD RVAD (Impella Cardiosystems GmbH) was functioning correctly. At this time there was no leakage originating from the PTFE. A few hours later a serous thoracic drainage appeared and massively increased to 800 mL/h within a short period of time. Laboratory analysis showed a hypoproteinemia and hypoalbuminemia. Natremia augmented from 132.3 ± 0.6 to 146.0 ± 2.0 mmol/L (p < 0.05), whereas osmolality increased from 299.6 ± 3.1 to 328.7 ± 5.6 mmol/kg (p < 0.05). A surgical revision identified a massive plasma leakage obviously originating along the entire PTFE prosthesis. At this time the patient was still dependent on the device. Therefore we decided to wrap the entire prosthesis with a bovine pericardial patch (St. Jude Medical, Inc, St. Paul, MN) sutured with Prolene 5-0 (Ethicon, Somerville, NJ) and tightly (proximally and distally) as well as approximately every centimeter around the prosthesis with Mersilene (Ethicon Inc, Sommerville, NJ) ligatures (Fig 1). The cavity between the patch and the PTFE prosthesis was filled with fibrin glue. The procedure was efficient, the evolution was favorable, and the device did not need to be replaced. The patient could be successfully weaned from the Impella RD RVAD (Impella Cardiosystems GmbH) 3 days later, and further recovery was uneventful.
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Fig 1. Operative photograph during explantation showing the pericardial patch wrapped tightly around the prosthesis. The partial opening of the pericardial patch demonstrates the collection of plasma around the prosthesis.
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Comment
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The Impella RD RVAD (Impella Cardiosystems GmbH) is a compact axial pump specially designed to assist and unload the right ventricle with a simplified access to both the right atria and the pulmonary artery (See
www.impella.com). The implantation can be carried out off-pump using a tangential pulmonary artery clamping to perform an end-to-side anastomosis with the PTFE arterial prosthesis. The initial clinical results are very satisfying and this pump seems to be an ideal assist device for short-term ventricular support [7]. Indeed the implantation technique of this mini-pump is a simple one, and immediate support of the failing right ventricle is warranted. However despite successful hemodynamic assistance, we experienced a significant plasma leakage here through the PTFE prosthesis that rapidly and dramatically developed 48 hours after implantation. The patient's hemodynamics remained unstable, thus precluding weaning and removal of the pump. Wrapping the PTFE graft with bovine pericardium was attempted and seemed to represent a satisfactory alternative to contain the plasma leakage. Multiple sutures were placed along the prosthesis (Fig 1). Obviously the replacement of the Impella RD RVAD (Impella Cardiosystems GmbH) would have been the ultimate choice if the wrapping would have been unsuccessful.
Plasma leakage with subsequent perigraft seroma is a well known complication observed with artificial vascular graft including PTFE prosthesis [1, 3, 4]. The cause of this leakage is not clearly understood but a reduced balance between the permeability of the prosthesis and the ability of the surrounding fibrous tissue to mechanically contain the leakage has been hypothesized. Especially a change from a hydrophobic to hydrophilic state was suggested to be possibly induced by chemicals such as antibiotic solutions of povidone iodine [6] and heparin [1]. The porosity of the conventional PTFE vascular graft (20 to 30 µm internodal distance) probably also plays a significant role regarding the permeability of the material, even though the leakage would be expected to appear rapidly after implantation and not only 48 hours later. On the one side, a low porosity obviously would reduce permeability; however on the other side the neointima formation is improved within 60 µm porosity of the PTFE graft [8]. The quality of tissue surrounding the prosthesis may also play a role in the development of a perigraft seroma. In fact it has been observed that seromas seem to occur more frequently around bypasses implanted into the thoracic cavity [1, 5] as opposed to peripheral arterial bypasses [3]. Fibroblast inhibitor factors were also found to possibly be induced by the graft itself and may play a significant role in the prevention of a local fibrotic and containing reaction [3, 9]. In our case the sternotomy was left open so that the prosthesis was not physically embedded in the surrounding tissue. In addition it is possible that the required heparin and the iodine impregnated gauzes that were used to cover the wound have both contributed to the development of the leak. Finally, other drugs typically used in the setting of a cardiac transplantation have not yet been associated to such PTFE leakage but may still have contributed to the problem.
In conclusion, this report demonstrates life-threatening plasma leakage through the PTFE prosthesis of the Impella RD RVAD device (Impella Cardiosystems GmbH). Wrapping the prosthesis with xenopericardium is an efficient and simple way to resolve this serious problem.
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References
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Abstract
Introduction
