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J Thorac Cardiovasc Surg 1997;114:287-289
© 1997 Mosby, Inc.
BRIEF COMMUNICATIONS |
Münster, Germany
Received for publication Nov. 12, 1996. Accepted for publication Jan. 15, 1997. Address for reprints: Hans H. Scheld, MD, Klinik und Poliklinik für Thorax-, Herz- & Gefäßchirurgie, Westfälische Wilhelms-Universität Münster, Albert-Schweitzer-Str. 33, 48129 Münster, Germany.
Improved surgical techniques and sophisticated postoperative care have led to impressive long-term results for the implantable left ventricular assist device (LVAD) as a bridge to transplantation in patients with end-stage cardiac failure. However, all of the currently used assist devices are less than perfect, and only about 70% of patients supported with an LVAD eventually undergo transplantation. Apart from preoperative multiorgan failure, bleeding, thromboembolism, and infection still jeopardize the successful outcome and contribute to significant postoperative morbidity, because most of the patients have one or more of these adverse events. We report on a life-threatening complication, which has occurred in two of our six patients with the TCI-HeartMate system (Thermo Cardiosystems, Inc., Woburn, Mass.) and which seems to occur more often than expected.
1
Clinical summaries
PATIENT 1
A 56-year-old male patient with end-stage ischemic heart disease was awaiting heart transplantation. Because of recurrent left ventricular decompensation and ongoing New York Heart Association class IV status, we decided to implant the TCI system as a bridge to transplantation. The patient fulfilled all criteria defined for patient selection. The LVAD was implanted with the heart beating, as has recently been described for the Novacor system (Baxter Healthcare Corp, Novacor Div., Oakland, Calif.). 2 Initially, the postoperative course was uneventful except for placement of a chest tube for left-sided pleural effusion. The patient recovered well, with a pump output of 7 to 8 L/min, and organ function steadily improved. He was fully mobile when blood suddenly poured from the cutaneous exit of the drive line on postoperative day 22. A chest x-ray film revealed widening of the mediastinal structures but otherwise normal findings. After a sudden drop of the hemoglobin and hematocrit levels, the preperitoneal device pocket was reopened and massive clots poured out, suggesting severe bleeding. Immediate sternotomy was performed and extracorporeal circulation was instituted on an emergency basis. A transverse tear of 2 to 3 mm within the inflow conduit close to the proximal edge of the metallic cage support, protecting the Dacron conduit, became evident. Because of the massive blood loss, the left atrial filling pressure decreased and air was sucked into the lacerated Dacron tube of the inflow conduit. The LVAD was stopped immediately and the tear in the inflow conduit closed with felt-patch reinforced sutures, French glue, 3,4 and double wrapping with a size 24 Dacron prosthesis. TCI LVAD support was reinstituted and no residual leakage was present. Despite meticulous deairing of the LVAD, massive cerebral air embolism caused brain death during the postoperative period. Pathologic examination confirmed rupture of the inflow conduit (Fig. 1).
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5 In 1988, a threaded outflow connector loosened in one patient, who required reoperation. Subsequently, the design was modified and a locking mechanism incorporated. 6 Very recently, Mehta and Pae 1 reported on a patient with erosion of the inlet cannula of the TCI system. Personal communications have revealed similar problems at other institutions. In our two patients, multiple transverse tears developed within the inflow conduit, presumably related to erosion of the Dacron tube by the edge of the covering metallic cage. Inasmuch as bleeding in the first patient became evident after mobilization, one may hypothesize that repetitive and inadequate bending of the conduit may have resulted in erosion of the Dacron tube. The adjacent inflow valve with its rigid anulus may additionally act as an anchor, thus increasing wall stress and promoting the laceration. We do not think that the Dacron tube is unsuitable, because valved Dacron conduits are not new and their durability has been proved by aortic operations.
It has been stated that the shorter inflow cannula of the TCI system is more advantageous than that of the Novacor systems in terms of placing the pump in the upper portion of the abdomen, below the costal margin. 7 It is possible that a longer inflow conduit may be less prone to bending forces during patient mobilization. Moreover, if rupture of the inflow conduit is suspected, preparation is hard to achieve during surgical revision and the short TCI inflow conduit renders exposure even more difficult. Apart from tremendous bleeding, aspiration of air through the lacerations may also seriously jeopardize the patient's condition, particularly the cerebral function, during subsequent transplantation or other surgical procedures. In this situation, extracorporeal circulation must be instituted immediately and the LVAD stopped before complete exploration. Aggressive surgical management is surely warranted, as stated by Mehta and Pae. 1 Theoretically, inflow valve dysfunction may occur as well, even if it seems unlikely. The metallic sheath has since been redesigned and is now less mobile, because it is fixed to another metallic ring by a string.
In conclusion, rupture of the inflow conduit close to the inflow valve is a life-threatening complication of the TCI system with the mobile cage support, which occurs more often than expected. Possible mechanisms include multiple bending limited by the metallic cage support resulting from suboptimal placement, while the valvular anulus might be acting as an anchor. Patients with possible bleeding should receive aggressive treatment, even though exchange and replacement of the inflow conduit is a demanding task. The metallic sheath has recently been redesigned, and future patients may no longer be at risk for this complication.
Footnotes
From the Departments of Thoracic and Cardiovascular Surgery,a Anesthesia and Operative Intensive Care Medicine,b Westfalian Wilhelms-University, Münster, Germany. 
References
This article has been cited by other articles:
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  C. F. Russo, P. A. Fratto, F. Milazzo, and E. Vitali Successful replacement of malfunctioning TCI HeartMate LVAD with DeBakey LVAD as a bridge to heart transplantation Interactive CardioVascular and Thoracic Surgery, December 1, 2004; 3(4): 542 - 543. [Abstract] [Full Text] [PDF]
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 A El-Banayosy, L Arusoglu, L Kizner, O Fey, K Minami, and R Korfer Complications of circulatory assist Perfusion, July 1, 2000; 15(4): 327 - 331. [PDF]
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 A. El-Banayosy, M. Deng, D.Y. Loisance, H. Vetter, E. Gronda, M. Loebe, and M. Vigano The European experience of Novacor left ventricular assist (LVAS) therapy as a bridge to transplant: a retrospective multi-centre study Eur. J. Cardiothorac. Surg., June 1, 1999; 15(6): 835 - 841. [Abstract] [Full Text] [PDF]
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 W. Piccione Jr., W. G. Kao, A. Mattea, E. R. Rodriguez, and R. G. Trohman Failure Of An Implantable Left Ventricular Assist Device: A Distinctive Electrocardiographic Pattern Before Malfunction J. Thorac. Cardiovasc. Surg., June 1, 1998; 115(6): 1376 - 1378. [Full Text] [PDF]
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