Ann Thorac Surg 2006;82:916
© 2006 The Society of Thoracic Surgeons
Original article: Cardiovascular
Invited commentary
François Lacour-Gayet, MD
Pediatric Cardiac Surgery, Denver Children's Hospital, University of Colorado, 1056 E 19th Avenue, Denver, CO 80218
(Email: lacour-gayet.francois{at}tchden.org).
This article [1] from the group in Indianapolis is the first report on Contegra (Medtronic, Minneapolis MN) jugular valved conduit implantations in the United States. The ideal right ventricle to pulmonary artery valved conduit substitute does not exist. The cryopreserved pulmonary homograft remains the favored material today. As outlined by the authors, the small size homografts used in infant and young children are far from being ideal. Early deterioration and short supply in small sizes are a real matter of concern. The bovine jugular vein conduit, distributed by Medtronic as Contegra offers a very interesting alternative.
As acknowledged by the authors, Contegra (Medtronic) is "surgeon friendly." The jugular tissue is very safe to handle, being both pliable and strong. Its very thin and resistant tri-leaflet venous valve is quite unique. No additional material is needed for the proximal anastomosis to the right ventricle. It is permanently available off the shelf including small diameters. Early valve deterioration has not been observed.
Two complications have been reported: (1) valvar insufficiency and (2) distal anastomosis stenosis.
Some degree of dilation of this conduit made of venous tissue was expected. Most of the published series have not reported important valvar insufficiency unless the conduit is exposed to high pressure, as in cases of high pulmonary resistance or pulmonary branch stenosis in which aneurysms are reported. In presence of elevated pulmonary artery pressure, a stronger conduit like an aortic homograft is more suitable.
Distal anastomotic stenosis was reported in several publications. The causes of the distal stenosis are probably multifactorial. Distal anastomotic stenoses were also observed with homografts in the Ross series [2] and when using Gore-Tex nonvalved conduits (W.L. Gore & Assoc, Flagstaff, AZ) [3] in truncus arteriosus repairs. We have observed this complication occasionally in our personal experience on nearly one hundred implantations. The first explanation seems mechanical. The height of the Contegra valve (Medtronic) is unusually long, measuring around 20 mm; if the distal end of the conduit is not cut short, exactly at the level of the commissures, the conduit could be too long and buckle near the end. The anastomosis should be performed as distal as possible or extended to the left pulmonary artery branch as recommended by the authors. The other hypothesis is immunological. The glutaraldehyde treatment should theoretically neutralize antigen activity. In reality, it is very likely that this xenogenic tissue contains substantial residual antigenicity particularly on the adventitial surface, where both class I and II major histocompatibility complex (MHC) residual antigens peptides can remain active as well other non-MHC xenoantigens reside. As pointed out by the authors, the adventitia should not be incorporated into the anastomosis in doing a precise "kissing endocardium" anastomosis. A careful rinsing of the prosthesis is necessary. When respecting these two precautions, a distal stenosis is unlikely to occur.
Furthermore, jugular bovine valves may also have a bright future in the catheterization laboratory because today in Europe, the interventional cardiologists are using this jugular vein leaflet to perform percutaneous valve replacement.
For the past 7 years, the European centers have been using Contegra (Medtronic) jugular valved conduits and leaflets since the European Community mark was delivered in 1999.
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References
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- Brown JW, Ruzmetov M, Rodefeld, MD, Vijay P, Darragh RK. Valved bovine jugular vein conduits for right ventricular outflow tract reconstruction in childrenan attractive alternative to pulmonary homograft. Ann Thorac Surg 2006;82:909-916.[Abstract/Free Full Text]
- Rubay JE, Shango P, Clement S, et al. Ross procedure in congenital patientsresults and left ventricular function. Eur J Cardiothorac Surg 1997;11:92-99.[Abstract]
- Behrendt DM, Macdonald III D. Truncus arteriosusrepair with a valveless conduit in neonates. J Thorac Cardiovasc Surg 1995;110:1148-1150.[Free Full Text]
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