Ann Thorac Surg 2007;83:185-187
© 2007 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Right Ventricular Outflow Tract Reconstruction With Contegra Monocuspid Transannular Patch in Tetralogy of Fallot
Bruno Chiappini, MD, PhDa,*,
Catherine Barrea, MDb,
Jean Rubay, MD, PhDa
a Departments of Thoracic and Cardiovascular Surgery, St. Luc Hospital, Université Catholique de Louvain, Brussels, Belgium
b Department of Pediatric Cardiology, St. Luc Hospital, Université Catholique de Louvain, Brussels, Belgium
Accepted for publication July 31, 2006.
* Address correspondence to Dr Chiappini, Department of Thoracic and Cardiovascular Surgery, St. Luc Hospital, 10 Ave Hippocrate, 1200 Bruxelles, Belgium (Email: bruno_chiappini{at}hotmail.com).
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Abstract
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BACKGROUND: Pediatric diminutive right ventricular outflow tract (RVOT) reconstruction with homografts or porcine xenografts remains challenging because of limited availability, early degeneration, tissue ingrowth, and child growth. The objective of this study was to assess whether Contegra valved bovine conduit, implanted as monocuspid transannular patch, might be an interesting alternative to overcome these problems.
METHODS: We reconstructed the RVOT of 12 patients with tetralogy of Fallot, by the use of a Contegra conduit, tailored as a monocuspid valved transannular patch. The patients were 4 females and 8 males, with a mean age of 12.8 ± 15.1 months and a mean weight of 7.2 ± 1.9 kg. The mean pulmonary artery annulus size was 8.2 ± 1.6 mm.
RESULTS: The Contegra tissue was suitable for suturing and for reconstruction of even severely hypoplasic RVOT . We did not observe any sign of conduit or valve degeneration during the follow-up of 28.1 ± 17.1 months. There were no early or late deaths, and no device-related adverse events. A peak transvalvular gradient of 36.5 ± 4.7 mm Hg was measured by echocardiography in 4 patients postoperatively, and it decreased during the follow-up to 20 ± 7.6 mm Hg. Pulmonary valve incompetence was grade 3 in 2 patients and grade 4 in 2 patients.
CONCLUSIONS: The Contegra monocuspid transannular patch is widely applicable to RVOT reconstruction with satisfactory midterm results, particularly in patients with small pulmonary annulus. Its main advantage is to reduce the potential risk of supravalvular stenosis due to the narrowing at the distal suture line, as demonstrated when used as conduits, especially in the smaller sizes.
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Introduction
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A broad variety of congenital malformations, truncus arteriosus communis, double outlet right ventricle, tetralogy of Fallot, and others need right ventricular outflow tract (RVOT) reconstruction. Different techniques, such as implantation of bioprostheses fixed in woven Dacron tubes, bovine pericardial valves, stentless valves, homografts, or valvuloplasties are used to reconstruct the continuity between the right ventricle and the pulmonary arteries. Appropriate-sized homografts are not always available, and they lack long-term stability [1–5]. Porcine xenografts often deteriorate rapidly [6–8].
To overcome these limitations, the Contegra conduit (Medtronic, Minneapolis, Minnesota) derived from a bovine jugular vein with a trileaflet venous valve has been developed and introduced in human clinical practice. The Contegra conduit is treated by a buffered low-pressure glutaraldehyde fixation. No additional anticalcification treatment is used. The conduits are available in sizes from 12 to 22 mm. Early results in humans have emerged [9–12], although there is limited information for infants and young children. Moreover, Meyns and colleagues [13] have highlighted the potential problem of supravalvar conduit stenosis developing during intermediate follow-up, particularly in the smaller conduits. We reviewed our experience about RVOT reconstruction in patients with tetralogy of Fallot by the use of a transannular monocusp valved patch, tailored from a Contegra conduit.
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Patients and Methods
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From 2000 to 2005, 12 children underwent a surgical repair of the tetralogy of Fallot with the implantation of a transannular monocusp patch tailored from a Contegra conduit, at the Department of Pediatric Cardiovascular Surgery, St Luc Hospital, Brussels. Our Institutional Review Board approved this study, and individual consent for the study was obtained. The patients were 4 females and 8 males, with a mean age of 12.8 ± 15.1 months (range, 3 to 58) and a mean weight of 7.5 ± 2.4 kg (range, 4.9 to 11.4 kg). Initial diagnosis included tetralogy of Fallot with severe hypoplasia of the pulmonary root, often associated with hypoplasia of the pulmonary arteries (Table 1). Three patients underwent previously a modified Blalock shunt. The size of the Contegra conduit was 14 mm in 7 patients, 16 mm in 3 patients, and 20 mm in 2 patients.
Surgical Technique
All patients were operated on using standard cardiopulmonary bypass, under normothermia. A transannular right ventricular–pulmonary incision was used in all cases, keeping the ventricular portion as cephalad as possible. The pulmonary valve was fully resected. Ventricular septal defect was closed with a Hemashield patch (Boston Scientific, Natick, Massachusetts). When a transannular patch is used, the distal extent of the incision into the pulmonary trunk is of major consideration to enlarge successfully the RVOT. In the case of a too short incision, the patch relieves only the small component of the high resistance produced by the length of the narrowing, and the gradient will persist essentially unchanged and be at the junction of the patch and distal pulmonary trunk. In some patients, the distal pulmonary trunk was narrower than the annulus; in those cases, we extended the incision into the left pulmonary artery, which usually continues in the same general direction as the pulmonary trunk and is usually proportionally larger than the distal pulmonary trunk.
The transannular patch was cut from a Contegra conduit to obtain a monocusp valved graft. Ideally, to reach a diameter of 14 mm (from 13.3 mm to 15.3 mm, corresponding to a body surface area from 0.30 to 0.40), the monocusp valve should be trimmed from a 20-mm diameter Contegra. This measurement allows half of the circonference of the pulmonary anulus to be fulfilled by one cusp. When the time came for inserting the patch and the distal end of the incision was on the pulmonary trunk, the conduit was stretched slightly and cut to the length of the incision, cutting both ends squarely. The conduit was then cut longitudinally so that about three fifths of the circumference remains as the roof. Only the corners were trimmed at the distal end, leaving them very broad, while the proximal end was tapered. The conduit was sewn into place with a continuous 5-0 polypropylene suture, starting at the distal end of the incision; suturing was then continued down on each side to the annulus level. When the incision had been carried onto the left pulmonary artery, a slightly different technique was used, in the belief that the result was more apt to geometrically correct. For this, a rectangular piece of pericardium was cut about 1.5 times wider than the apparent diameter of the left pulmonary artery and about 1.5 times longer than the incision in the left pulmonary artery. The pericardial patch was sewn into place with continuous 6-0 polypropylene sutures placed slightly farther apart in the patch than in the wall of the left pulmonary artery.
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Results
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The mean cross-clamp time was 56.8 ± 13.2 minutes (range, 44 to 93), and the mean extracorporeal circulation time was 110.2 ± 24.5 minutes (range, 78 to 154). The mean intensive care unit stay was 3.9 ± 3.6 days. In 1 patient (8.3%) a complete atrioventricular block developed and required pacemaker implantation; 1 patient (8.3%) experienced pneumonia during the early postoperative period. There was no hospital mortality after initial surgery and no perioperative morbidity related to the patch. Four patients had trivial pulmonary regurgitation at echocardiography before hospital discharge. Early postoperative echocardiographic assessment before discharge and after a mean follow-up of 21.1 ± 17 months demonstrated acceptable hemodynamic characteristics with a mean peak gradient across the valve of 36.5 ± 4.7 mm Hg at discharge versus 20 ± 7.6 mm Hg at follow-up. At last follow-up, pulmonary insufficiency was trivial or mild (grade 1 to 2/4) in 7 patients, moderate (grade 3/4) in 2, and severe (grade 4/4) in 2 patients. No late death or reoperation occurred during the follow-up period. No patient was under anticoagulant treatment, and none experienced any thromboembolic complication.
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Comment
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So far the ideal conduit to connect the right ventricle to the pulmonary artery does not exist. A small homograft is still considered by most as the gold standard for neonatal and infant RVOT reconstructions [4, 8, 14]. Expanding indications for repair of congenital as well as acquired heart diseases have led to lack of availability, mostly of smaller sized homografts. Moreover, small homografts used in neonates and small children require replacement because of relative stenosis due to outgrowth, unfavorable blood flow in oversized homograft, recipient’s immunity, and accelerated calcium turnover in children ([4, 15–17]). In the past, a large number of valved xenografts were developed and implanted in the pulmonary position, with the main advantage of the unlimited availability for all pediatric and adult sizes [11, 18–24].
Initial published clinical results after repair of the RVOT using a Contegra conduit in humans have been encouraging [9, 10]. Breymann and coworkers [25] have recently reported about 108 Contegra conduits extending the mean follow-up to 4 years, reporting 10 cases of supravalvar stenosis (9.3%) that was similar to the incidence of acquired conduit stenosis at the distal suture line (11.6%) reported by Boething and colleagues [26] and Shebani and coworkers [27]. Conduit narrowing at the pulmonary anastomosis (distal suture line) was relatively common in the latter series and predominantly occurred in the smaller sized conduits (12 and 14 mm). The acquired stenosis at the distal part of the conduit may be partly related to discrepancies in circumference between the smaller conduits and the native pulmonary arteries. High pressure in the conduit may lead to aneurysmal dilatation and result in valvar regurgitation. In the Shebani series [27], almost one third (27.5%) of the conduits developed a degree of dilatation over time.
Local thrombotic processes leading to early valvar failure is another significant complication after Contegra conduit implantation [27–29]. Indeed, the valvar cusps of the jugular vein graft are deeper than semilunar valvar cusps, which might predispose them to in situ thrombosis. In our early experience, we used alternative, less costly materials such as monocusp made from Gore-Tex (W. L. Gore & Assoc, Flagstaff, Arizona) surgical membrane that is economically more attractive and associated with good results in many series of patients [30, 31]. Our experience with Gore-Tex monocusp was characterized by 2 patients who needed reoperation because of stenosis at the distal anastomosis of the transanular patch, as described by Iemura and colleagues [32], and 3 patients who had significant pulmonary valve incompetence a few months after surgery.
In this study, we report our first experience with the use of a monocusp patch prepared from a Contegra conduit, implanted in pediatric patients with tetralogy of Fallot. This is the first report on this topic, and our clinical results seem to be encouraging to further improve the use of a Contegra patch for the RVOT reconstruction. The patch consists of an exceptionally pliable tissue that offers unique characteristics for surgical handling, suturing is easy, and the material is resistant to suture tear. Up to now, there have been no device-related adverse events during the 21.1 ± 17 months of follow-up. This preliminary experience lets us hope that the Contegra monocusp patch might become a promising alternative to the homograft, the still well-accepted gold standard for RVOT reconstruction.
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Abstract
Introduction
