Ann Thorac Surg 1996;62:893-895
© 1996 The Society of Thoracic Surgeons
Case Report
Double-Orifice Right Atrioventricular Valve Associated With Partial Atrioventricular Septal Defect
Brian Prendergast, FRCS,
Andrew Tometzki, MRCP,
Pankaj S. Mankad, MD
Department of Cardiac Surgery, Royal Hospital For Sick Children, Edinburgh, United Kingdom
Accepted for publication March 30, 1996.
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Abstract
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We describe the case of a double-orifice right atrioventricular valve that was discovered at operation for an associated atrioventricular septal defect. The diagnosis and operative management are discussed. Developmental concepts illustrate the mechanism by which this defect arises, and emphasize that its great rarity remains an enigma.
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Introduction
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Although the occurrence of a double-orifice mitral valve is no rarity [1] (indeed, such valves are recognized to occur in association with atrioventricular septal defects [AVSDs] [2]), the finding of a double-orifice tricuspid (or right-sided) valve remains extremely rare [3]. With a single exception [4], reports in the literature concern only autopsy specimens [2,5–7]. Furthermore, to our knowledge, only one case of double-orifice right atrioventricular (AV) valve has been described previously in association with an AVSD [3].
Recently we encountered at operation an infant with double-orifice right AV valve in association with partial AVSD. The surgical procedure was slightly modified to achieve a competent valve and satisfactory repair.
After an uneventful full-term gestation the infant was delivered by an emergency cesarean section as a footling breach. She required no resuscitation but was observed to have a disproportionately high body weight (4.2 kg) for her length, which lay on the 50th percentile for growth. Soon after her birth, she was noted to be tachypneic at rest and to be having difficulty with feeding. Physical examination revealed a 3/6 pansystolic murmur at the left sternal edge and a 2/6 midsystolic murmur over the pulmonary area. The second heart sound was widely split. There was no hepatomegaly, and all limb blood pressures were equal. Baseline hematologic and biochemical investigations were within normal limits.
Chest radiography demonstrated an enlarged heart (cardiothoracic ratio, 0.66) with plethoric lung fields. An electrocardiogram showed peaked p waves and right bundle branch block. An echocardiogram visualized both a partial AV and an atrial septal defect within the oval fossa. There was a tiny patent ductus arteriosus. Moderate regurgitation was identified across both left- and right-sided AV valvar orifices, although this initially appeared to be associated with anatomically normal valves. Initially the baby's cardiac failure responded well to medical management, but by the age of 5 months, she was failing to thrive, with height and weight below the third growth percentile. Cardiac catheterization was performed, which showed an aortic saturation of 81% with pulmonary hypertension. Mean left and right atrial pressures were equal at 8 mm Hg, with significant shunting at the atrial level. Other pressures were recorded as left ventricle, 65/4 mm Hg; femoral artery, 65/36 (45) mm Hg; and pulmonary artery, 60/20 (36) mm Hg.
Operation was performed at the age of 7 months. Intraoperative findings were as expected for a partial AVSD, but in addition a double orifice was noted in the right AV valve. The two orifices were separated by a tongue of leaflet in the tissue, which had its own chordae tendineae and papillary muscles. This produced anteromedial and (slightly smaller) posterolateral valvar orifices (Fig 1
). There was moderately severe overall dilatation of the right AV junction, which produced valvar incompetence. The repair was performed using an autologous pericardial patch in the standard fashion. The right AV valvar orifice was narrowed by making the edge of the pericardial patch along the right side of the ventricular septal rim shorter than the combined length of the two adjoining right AV valve leaflets. The accessory central dividing tongue and its tension apparatus were left intact. The cleft in the left AV valve was closed. Hemodynamics immediately after bypass showed mean pressures in the left atrium of 6 mm Hg; right atrium, 5 mm Hg; aorta, 78/35 mm Hg; and pulmonary artery, 38/12 mm Hg. The child made an uneventful recovery and was discharged home on the sixth postoperative day. Subsequent echocardiography confirmed satisfactory repair, with little intracardiac shunting and no residual right or left AV valvar regurgitation.
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Fig 1. . Intraoperative photograph (surgeon's view) demonstrating the larger anteromedial and smaller posterolateral orifices.
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The preoperative echocardiogram was reviewed critically after the procedure. On a subcostal four-chamber view, two orifices were identified within the right AV valvar orifice (Fig 2). Furthermore, color flow mapping revealed that the anteromedial orifice was regurgitant, whereas the posterolateral orifice appeared competent.
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Fig 2. . Subcostal four-chamber view, showing the double orifice right atrioventricular valve (arrows). (LA = left atrium; LV = left ventricle; RA = right atrium.)
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Comment
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Several different mechanisms have been described to produce accessory orifices in left AV valves in the setting of AV septal defects. These include a chordal ring, an accessory papillary muscle or muscles, a subdividing muscular ridge, fused papillary muscles, crossing chordae tendineae, and central fibrous subdivision. Although this anomaly is well known in the mitral position, a double orifice in the tricuspid valve remains an extreme rarity both surgically and pathologically. With the exception of one report, the few cases in the literature are from autopsies. We have described a patient with double-orifice right AV valve (in association with partial AVSD), caused by a central leaflet tissue with its papillary muscle, diagnosed and physiologically corrected at operation.
Three anatomic types of double-orifice AV valves are recognized [3]. In all patients, the presence of accessory subvalvular components distinguish the true double-outflow valve from a simple valve fenestration. The location of the second orifice then forms the basis of classification. In the "hole type" the second orifice may simply reflect a hole in one leaflet. Such valves may show only rudimentary subvalvular components.
In the commissural type, the accessory orifice is found at the end of the zone of apposition. Careful inspection reveals the associated subvalvar apparatus to be appropriate to the adjacent leaflets, although accessory papillary muscles may also be present. In central type, a bridge of tissue is seen to join together otherwise normally formed leaflets. Our patient had a central type of double orifice. The valve was made competent at operation by narrowing the annulus as described above. This was successful, as the cause of valvular incompetence was annular dilatation secondary to an increased right heart volume load, which was attributable to a large left-to-right shunt. The central tongue of leaflet tissue was left intact, as previously recommended for double orifices in the left AV valve.
The leaflets of the tricuspid valve are believed to develop equally from the endocardial cushion tissues and the myocardium [8]. The presence of an anomaly of the leaflets of a right-sided valve in association with endocardial cushion defect (AVSD), therefore, is not surprising. Its rarity nonetheless remains an enigma.
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Acknowledgments
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We are grateful to Professor R. H. Anderson for his valuable suggestions.
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Footnotes
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Address reprint requests to Dr Mankad, Department of Cardiac Surgery, Royal Hospital For Sick Children, Sciennes Rd, Edinburgh, EH9 1LF United Kingdom. (E-mail: pankaj.mankad{at}ed.ac.uk).
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References
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- Cascos AS, Rabago P, Sokolowski M. Duplication of the tricuspid valve. B Heart J 1967;29:943–5.
- Edwards JE, Carey LS, Neufeld HN, Lester RG. Congenital heart disease. Correction of pathological anatomy and angiography. Philadelphia: Saunders, 1965:126,410.
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- Lamers W, Viragh S, Wessels A, Moorman A, Anderson R. Formation of the tricuspid valve in the human heart. Circulation 1995;1:111–21.
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Abstract
Introduction
