Ann Thorac Surg 1997;64:861-862
© 1997 The Society of Thoracic Surgeons
How To Do It
Successful Implantation of Thoratec Assist Device: Wrapping of Outflow Conduit in Hemashield Graft
Kazutomo Minami, MD, PhD,
Latif Arusoglu, MD,
Toshiya Koyanagi, MD,
Aly El-Banayosy, MD,
Michael M. Körner, MD,
Reiner Körfer, MD, PhD
Department of Thoracic and Cardiovascular Surgery, Heart Center North Rhine-Westphalia, University of Bochum, Bad Oeynhausen, Germany
Accepted for publication April 1, 1997.
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Abstract
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Persistent oozing and bleeding through the wall of the built-in outflow conduit in mechanical circulatory assist devices is a troublesome problem. Wrapping the outflow conduit of Thotatec in a Hemashield graft without preclotting completely prevents oozing and bleeding.
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Introduction
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Mechanical circulatory support systems have been applied effectively in patients with postcardiotomy cardiogenic shock and as a bridge to cardiac transplantation. There are several kinds of mechanical circulatory assist devices, for example, Thoratec (Thoratec, Berkeley, CA) [1], Novacor (Novacor Division, Baxter Healthcare Corp, Oakland, CA) and HeartMate (Thermo Cardiosystems Inc, Woburn, MA). However, a troublesome problem sometimes occurs during the implantation procedure. We encountered persistent and extensive oozing and bleeding through the wall of the built-in Thoratec outflow conduit. Although the outflow conduit ought to be preclotted with the patient's nonheparinized blood, this is not possible in already heparinized patients, for instance, patients with postcardiotomy cardiogenic shock [2]. The technique of preclotting itself is also laborious and time consuming. It is not easy to remove coagulum and clots from the inside of the outflow conduit. Even if preclotting is properly carried out in advance, it does not always adequately prevent oozing. Our experience has demonstrated that wrapping the original outflow conduit of the Thoratec device in a collagen-sealed vascular graft (Hemashield; Meadox Medicals Inc, Oakland, NJ) without preclotting completely prevents oozing and bleeding.
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Technique
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After insertion of the inflow conduit into the apex under cardiopulmonary bypass, the outflow conduit is covered with a Hemashield graft. A Hemashield graft 16 mm in diameter is selected, whereas the outflow conduit is 14 mm in diameter. The Hemashield graft is fastened firmly to the outflow conduit by ligation at the site of the velour cuff. Because the two grafts closely contact each other, they look like the same graft consisting of two layers (Fig 1
). The ascending aorta is partially clamped, and the double outflow graft together is anastomosed to the aorta by a single running suture using 4-0 Prolene (Ethicon, Somerville, NJ). After deairing is achieved through a small hole in the double outflow graft, the aortic clamp is released.
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Comment
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From September 1987 to March 1996, we have treated 270 patients with mechanical circulatory support systems. The Bio-Medicus centrifugal pump (Bio-Medicus, Eden Prairie, MN) was used in 72 patients, ABIOMED BVS system 5000 (ABIOMED, Danvers, MA) in 67, Thoratec in 84, Novacor in 29, HeartMate in 15, and MEDOS-HIA (MEDOS Medizintechnik GmbH, Stolberg, Germany) in 3. Our results of mechanical circulatory support for patients in postcardiotomy cardiogenic shock and as a bridge to cardiac transplantation are encouraging [3].
However, several factors impede successful implantation. Oozing and bleeding through the outflow conduit is one cumbersome problem. The outflow conduit of each device differs in material, weave, porosity, sealing, and diameter (Table 1). With the ABIOMED BVS system 5000 and Novacor, preclotting with blood is unnecessary because of the sealed graft. In contrast, preclotting must be accomplished with Thoratec and HeartMate. If a patient, for example, with postcardiotomy cardiogenic shock, is already systemically heparinized, an alternative method is required to prevent oozing. Aprotinin administration is certainly effective in reducing bleeding, but it is reported that severe anaphylactic shock may occur during operation as a consequence of aprotinin reexposure [4]. Therefore, we are cautiously readministrating aprotinin in patients with reoperation. Preclotting with blood or with cryoprecipitate and thrombin, spraying with fibrin glue, or autoclaving with albumin takes some trouble and has limitations. We hit upon wrapping the outflow graft in a Hemashield graft. The Hemashield graft is a woven double-velour polyester graft impregnated with highly purified collagen. Therefore, the Hemashield graft minimizes bleeding at implantation and eliminates the preclotting step. Wrapping of the outflow conduit in a Hemashield graft results in complete prevention of oozing. Therefore, preclotting of the outflow conduit is no longer needed.
We have used this technique in several recent cases and obtained satisfactory results. This technique provided reduction in bleeding and transfusion requirements. The mean postoperative blood loss decreased approximately 50% from the previous amount of 3 or 4 L. Because the two grafts fit closely together, the original outflow graft appears to be coated rather than overlapped by the Hemashield graft. It is feasible to anastomose the double grafts together to the aorta. Moreover, the chest can be closed without any difficulty. An additional advantage of the double graft is protection from graft injury by reexploration. Although, in fact, we have previously experienced reentry sternotomy graft injury in a few patients, such a complication has not occurred since adoption of the Hemashield graft. We have lately used this wrapping technique with a Hemashield graft (32 mm in diameter) in HeartMate patients. Wrapping of the outflow conduit in a Hemashield graft is a simple, easy, effective, and reliable method to prevent oozing through the wall of the outflow conduit.
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Footnotes
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Address reprint requests to Dr Minami, Herzzentrum NRW, Georgstr 11, 32545, Bad Oeynhausen, Germany.
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References
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- Farrar DJ, Lawson JH, Litwak P, Cederwall G. Thoratec VAD system as a bridge to heart transplantation. J Heart Transplant 1990;9:415–23.[Medline]
- Minami K, el-Banayosy A, Posival H, Seegewiss H, Körner MM, Körfer R. Improvement of survival rate in patients with cardiogenic shock by using nonpulsatile and pulsatile ventricular assist device. Int J Artif Organs 1992;15:715–21.[Medline]
- Körfer R, El-Banayosy A, Posival H, et al. Mechanical circulatory support: the Bad Oeynhausen experience. Ann Thorac Surg 1995;59:56–63.[Abstract/Free Full Text]
- Schulze K, Graeter T, Schaps D, Hausen B. Severe anaphylactic shock due to repeated application of aprotinin in patients following intrathoracic aortic replacement. Eur J Cardiothorac Surg 1993;7:495–6.[Abstract]
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Abstract
Introduction
