Ann Thorac Surg 2001;71:358-360
© 2001 The Society of Thoracic Surgeons
Case report
Double orifice right atrioventricular valve in atrioventricular septal defect: morphology and extension of the concept of fusion of leaflets
Marc A. Radermecker, MDa,
Jane Somerville, MDa,
Wei Li, MDa,
Robert H. Anderson, MDa,
Marc R. de Leval, MDa
a Department of Cardiothoracic Surgery, Great Ormond Street Hospital for Children NHS Trust, London, England, UK
Accepted for publication June 4, 2000.
Address reprint requests to Dr Radermecker, Department of Cardiovascular and Thoracic Surgery, University Hospital of Liège, CHU du Sart-Tilman, 4000 Liège, Belgium
e-mail: mradermecker{at}chu.ulg.ac.be
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Abstract
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A rare observation of a double orifice right atrioventricular valve in a partial form of atrioventricular septal defect is reported. The concept of leaflet fusion along part of their anticipated zones of apposition is used to explain the formation of this anomaly. We show that this concept can account for the different morphologic presentations of atrioventricular septal defect.
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Introduction
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The controversies concerning the morphology of the left and right atrioventricular (AV) valves in hearts with AV septal defect and common AV junction are attributable at least in part to the inappropriate use of terms such as commissure or cleft. It is our contention that the situation can be made clearer and simpler if the valve guarding the common junction is analyzed on the basis of five leaflets (Fig 1), with the spaces between the leaflets described as zones of apposition. In this light, we describe the morphologic observations made in a patient with double orifice in the right AV valve as they support the concept that every valvar arrangement in AV septal defect can be explained on the basis of fusion of leaflets along part of their anticipated zones of apposition.
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Fig 1. Basic arrangements of the five leaflet valve and relationship to the papillary muscles and ventricular septal crest in atrioventricular septal defect with common atrioventricular junction. (APM = anteropapillary muscle; ASL = anterosuperior leaflet; IBL = inferior bridging leaflet; IS = interventricular septum; LV = left ventricle; ML = mitral leaflet; MPM = medial papillary muscle; RV = right ventricle; SBL = superior bridging leaflet.)
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The valvar anatomy was assessed during complete surgical repair of a 38-year-old caucasian woman with a common atrium, common AV junction, and AV septal defect with separate right and left valvar orifices (partial defect).
Operation was performed on hypothermic cardiopulmonary bypass and cardioplegic arrest. The right atrium was opened obliquely in front of the crista terminalis. The left AV valve displayed the usual trifoliate configuration [1], with the mural component guarding a little less than one-third of the circumference of the left AV valve. The superior and inferior bridging leaflets were separated by a well-defined zone of apposition (the so-called septal commissure or cleft), and were attached firmly to the mildly "scooped out" ventricular septal crest. The zones of apposition between the mural leaflet and the left ventricular component of the bridging leaflets were widened. The right AV valve showed two distinct orifices, with overall annular distension because of right ventricular dilation. The leaflet tissue was not dystrophic, and the different leaflets were roughly in the same plane. The general appearance could be explained by the fusion of the posterior aspect of an extensive anterosuperior leaflet with the fused right ventricular aspect of the bridging leaflets (Fig 1). The area of bridging in the right orifice, composed of leaflet tissue, was itself attached with a subvalvar tension apparatus to a big anterior papillary muscle, producing a "pseudoparachute" configuration (Fig 2). This anterior papillary muscle was somewhat displaced anteriorly. The bridge of valvar tissue between the septal and anterosuperior leaflets showed limited mobility, as suggested by the preoperative echocardiogram. There was a medial papillary muscle supporting the area between the septal and anterosuperior leaflets, and a tiny posterior papillary muscle situated close to the anterior papillary muscle, supporting the commissure between the mural and anterosuperior leaflets and parts of the mural leaflet. The surface area of the anterior orifice was approximately 4 cm2 and that of the posterior orifice was 2 cm2. Operation consisted in repairing the left AV valve. The zone of apposition between the bridging leaflet was closed using interrupted sutures and the left AV valve annulus was reduced by plication at the junction between the mural and bridging leaflets. An autologous pericardial patch anchored on the right side of the ventricular septum leaving the conduction system and the coronary sinus on the left side was used to partition the common atrium. The double orifice right AV valve was nonstenotic, and was judged competent after saline injection.
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Fig 2. Illustration of the double orifice right atrioventricular valve with emphasis on the subvalvar apparatus supporting the tissue bridge between the septal and anterior leaflets (lower right).The left component of the atrioventricular valve is schematically represented.
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Comment
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It is generally held that an accessory orifice within the left AV valve is found in 5% of patients with AV septal defect [2, 3]. As far as we are aware, only one report in the recent literature has described a dual orifice in the right component of the basically common AV valve [4]. The concept of bridging between two distinct and opposite leaflets as a result of fusion of leaflets over part of their zone of apposition accounts not only for the anomaly presently described, but also for dual orifices in the left AV valve, which is simply the consequence of a bridge of tissue joining one or other of the bridging leaflets to the mural leaflet [3]. This concept also accounts for the distinction between the common valvar orifice and separate right and left orifices (common versus partial AV septal defect). Thus, on the basis of the usual arrangement of five leaflets valve guarding the common AV junction, which is the essence of an AV septal defect, the so-called partial defect is readily explained by a bridge of leaflet tissue joining together the two bridging leaflets. The leaflets themselves, along with the bridge, are usually also attached to the crest of the ventricular septum, but this is not always the case. In our patient with a dual orifice in the right AV valve, the bridging between the anterosuperior and the septal leaflet, together with confluence of cord was not associated with significant stenosis or insufficiency, but may probably predispose in some patients to valvar stenosis. As with dual orifices in the left valve, it would have been injudicious to attempt to surgically remove the bridging tongue of leaflet tissue.
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References
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Wilcox B.R., Anderson R.H. Surgical anatomy of the heart. London: Churchill Livingstone, 1985.
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Warnes C., Somerville J. Double mitral valve orifice in atrioventricular defects. Br Heart J 1983;49:59-64.[Abstract/Free Full Text]
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Ebels T., Anderson R.H., Devine W.A., Debich D.E., Penkoske P.A., Zuberbuhler J.R. Anomalies of the left atrioventricular valve and related ventricular septal morphology in atrioventricular leaflet defects. J Thorac Cardiovasc Surg 1990;99:299-307.[Abstract]
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Honnekeri S.T., Tendolkar A.G., Lokhandwala Y.Y. Double-orifice mitral and tricuspid valves in association with the Raghib complex. Ann Thorac Surg 1993;55:1001-1002.[Abstract]
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