Ann Thorac Surg 2006;81:2321-2323
© 2006 The Society of Thoracic Surgeons
How to do it
Modified Technique for Heterotopic Implantation of a Right Ventricular Outflow Tract Conduit
Hitendu Dave, MD
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,
Ali Dodge-Khatami, MD,
Alexander Kadner, MD,
René Prêtre, MD
Division of Congenital Cardiovascular Surgery, University Children's Hospital, Zurich, Switzerland
Accepted for publication April 6, 2005.
* Address correspondence to Dr Dave, Division of Congenital Cardiovascular Surgery, University Childrens Hospital (Kinderspital Zurich), Steinwiesstrasse 75, Zurich, CH-8032 Switzerland (Email: hitendu.dave{at}kispi.unizh.ch; hitendu{at}hotmail.com).
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Abstract
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This article describes a modified technique of side-to-side proximal connection of a conduit during heterotopic implantation in the right ventricular outflow tract. It results in a better geometry of the right ventricular outflow and avoids distortion of the valve annulus, especially when the newer generation of straight xenografts are used.
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Introduction
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Indications for conduit insertion in the right ventricular outflow tract have significantly broadened after evidence that chronic pulmonary insufficiency can lead to irreversible right ventricular (RV) dilatation, ventricular arrhythmias, and sudden cardiac death [[1–3]. In this article we describe a method of proximal connection of the conduit to the right ventriculotomy, using a side-to-side anastomosis instead of the classic end-to-side approach, which appears to provide better geometry to the RV outflow, especially in heterotopic implantations of right ventricle to pulmonary artery conduits.
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Technique
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The right ventriculotomy was performed as cranially as possible between the aortic annulus and the left anterior descending coronary artery. The endocardial part of the ventriculotomy and the accessory muscles inserting at the edges were resected to provide a wider outflow.
Distal Anastomosis
The distal anastomosis was performed first. Wherever possible, the integrity of the pulmonary bifurcation was preserved, thus allowing three-dimensional growth of the bifurcation and normal distribution of blood to both lungs. In case of the bovine jugular vein graft (Contegra [Medtronic, Minneapolis, MN]), in which the commissural height is more than that of human semilunar valves, the level of distal transection was a correlate of the space available between the RV opening and the pulmonary bifurcation [[4].
Tailoring the Proximal Opening in the Conduit
The conduit was held straight and stretched a bit to maintain a short course and to determine the best position with respect to the ventricular opening. It was divided proximally at the level of the most caudal point on the ventriculotomy. A small oval strip of conduit wall was excised from the undersurface of the conduit, extending up to what would be the posterior midpoint on the proximal suture line. This opening on the undersurface was similar to an oblong opening on the side of the conduit that would be sutured to the side (opening) of the right ventricle (Fig 1A).
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Fig 1. Surgeon's view during proximal connection of right ventricular–pulmonary artery conduit. (A) Tailoring of the proximal end of the conduit. (B) Side-to-side anastomosis of the conduit to the right ventriculotomy leaving the proximal end open. (Inset) Linear closure of the open end and the completed anastomosis.
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Proximal Anastomosis
The suturing was started at the posterior midpoint, with successive bites running anteriorly on both sides. Further running polypropylene stitches were continued, including a generous amount of the conduit tissue, while curving along the proximal curvatures of the ventriculotomy, until both edges of the conduit met at their natural destinations on the ventriculotomy. This left a loop of opening on the proximal end of the conduit, which was linearly trimmed and sutured (Fig 1B). The whole operation was performed on a beating heart on cardiopulmonary bypass, provided that there was no residual septal defect that could aspirate air into the left heart.
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Results
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The proximal anastomosis and the conduit inflow appeared roomier and possessed a more homogenous outflow tract. The color Doppler examination during intraoperative transesophageal echocardiography showed laminar flow at the conduit inflow. The valve annulus was maintained in a plane perpendicular to the long axis of the conduit, thus optimizing the competence of the valve. There were no instances of coronary compression due to the conduit. The RV outflow showed absence of flattening or kinking as could occur with the classic technique.
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Comment
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Right ventricular outflow tract conduits usually degenerate due to the development of a stenosis at one of the anastomotic sites, or due to degeneration of the valve or the conduit wall [[5, 6]. Geometric distortions such as kinks, twists, flattening, as well as turbulence at the suture lines may precipitate early problems with the conduit [[5]. Because all of these conduits need to be eventually changed, present attempts are directed at improving their longevity. Heterotopic implantation of a right ventricular outflow tract conduit constitutes a challenging subgroup of these reconstructions where the conduit is inserted into an artificially created RV opening (as in the Rastelli operation, as in Truncus arteriosus, and as in pulmonary atresia repairs) because of a nonexistent RV infundibulum. Unlike pulmonary or aortic homografts, which have a natural curve, the new generation of xenografts (such as the bovine jugular vein graft) need their proximal end to be tailored so as to best fit the ventriculotomy. The proximal anastomosis of such a conduit to the neo-opening in the right ventricle can be tricky because ([1) the neo-opening in the RV is more horizontally oriented than vertically, subjecting the conduit to a high chance of kinking (Fig 2A); and ([2) the oval RV opening is not in geometric conformity to the rounded opening in the conduit, thus imposing a high chance of flattening the conduit at the level of RV outflow (Fig 2B).
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Fig 2. (A) Kink in the Contegra (Medtronic Inc, Minneapolis, MN) graft in a 3-year-old patient. (B) Schematic depiction of a flattened outflow in an end-to-side type anastomosis.
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The classic technique involves using a beveled shape of the proximal conduit opening to be anastomosed end-to-side to the RV opening. Such a technique is prone to geometric distortions that constrict the space in the RV outflow or lead to dissipation of flow kinetics due to a kinked path.
Because the tangential space available between (the planes of) the proximal and the distal end of the ventriculotomy is very small, the three-dimensional volumetric space at the proximal opening is significantly reduced. We used various methods to augment this space by putting an oval or triangular patch to increase the amount of conduit tissue available at the proximal anastomosis. It was the presently described method of side-to-side anastomosis that consistently enabled a better geometry. Although some amount of turbulence across the newer valved conduits is commonly observed, our proposed technique consistently results in a less turbulent flow at the graft inflow [[4]. In addition to the previously mentioned advantages, cranialization of the infundibular opening helps to mimic a natural RV outflow opening where the blood flow kinetics are more naturalized. The resultant orientation of the valve annulus in a vertical plane results in better competence of the valve. In conclusion, the described side-to-side implantation technique seems to be an easily reproducible method for consistently constructing a spacious proximal connection of an RV to pulmonary artery conduit without deforming the valve apparatus.
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References
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- Therrien J, Siu SC, Harris L, et al. Impact of pulmonary valve replacement on arrhythmia propensity late after repair of tetralogy of Fallot Circulation 2001;103(20):2489-2494.[Abstract/Free Full Text]
- Therrien J, Siu SC, McLaughlin PR, Liu PP, Williams WG, Webb GD. Pulmonary valve replacement in adults late after repair of tetralogy of fallotare we operating too late?. J Am Coll Cardiol 2001;37(7):2008-2009.[Free Full Text]
- Gatzoulis MA, Balaji S, Webber SA, et al. Risk factors for arrhythmia and sudden cardiac death late after repair of tetralogy of Fallota multicentre study. Lancet 2000;356:975-981.[Medline]
- Dave H, Kadner A, Berger F, et al. Early results of the bovine jugular vein graft used for reconstruction of the right ventricular outflow tract Ann Thorac Surg 2005;79(2):618-624.[Abstract/Free Full Text]
- Corno AF, Qanadli SD, Sekarski N, et al. Bovine valved xenograft in pulmonary positionmedium-term follow-up with excellent hemodynamics and freedom from calcification. Ann Thorac Surg 2004;78(4):1382-1388.[Abstract/Free Full Text]
- Stark J. The use of valved conduits in pediatric cardiac surgery Pediatr Cardiol 1998;19:282-288.[Medline]
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Abstract
Introduction
