Valve repair for mitral regurgitation associated with isolated double-orifice mitral valve

Abstract

Double-orifice mitral valve (DOMV) can occur as an isolated lesion or in association with other cardiac malformations of which atrioventricular canal defect is most common. 1 Isolated DOMV is, however, rarely identified when the valve is functioning normally. We present here a case with mitral regurgitation in isolated DOMV in which valve repair was done successfully. A 55-year-old man was referred to our hospital with exertional dyspnea. Physical examination showed a grade 4/6 holosystolic murmur at the left fourth intercostal space. The electrocardiogram showed atrial fibrillation. The chest x-ray film showed a dilated left atrium. Transthoracic two-dimensional and color Doppler echocardiography showed a DOMV with grade 4 mitral regurgitation because of a torn chorda at the mitral orifice of the anterolateral side. The left ventricular diastolic and systolic dimensions by echocardiography were 74 mm and 42 ram, respectively. Cardiac catheterization revealed a peak pulmonary capillary wedge pressure of 21 mm Hg. The left ventriculogram showed severe mitral regurgitation. An operation was done with the use of standard cardiopulmonary bypass with moderate hypothermia (28 ° C) and cold cardioplegic arrest. The left atrium was entered through the standard longitudinal incision. The mitral valve was found to have two orifices, which were completely separated by a fibromuscular bridging tissue (Fig. 1). The orifices were almost equal in size: the posteromedial orifice was 30 ram; the anterolateral orifice, 25 mm. Each orifice had its own site of chordal insertion. No cleft was identified on either the anterior or posterior leaflet of each orifice. One half of the posterior leaflet of the anterolateral orifice was found to have prolapse because of a torn chorda. A quadrangular segmental resection of the prolapsed posterior leaflet was done. Large, pledgeted 2-0 sutures were placed at the level of the anulus for plication. The split leaflet was sutured with interrupted 4-0 polypropylene sutures. Because the fibromuscular bridging tissue seemed to be unsuitable for placement of the annuloplasty ring, another pledgeted suture was added to reinforce the plicated anulus. By this procedure, the anterolateral orifice was reduced to 10 mm in diameter. Transesophageal Doppler echocardiography showed trivial mitral regurgitation from the repaired anterolateral orifice. The patient was discharged from the hospital on postoperative day 15 after an uneventful recovery. Various classifications for DOMV have been proposed on the basis of the size and location of the two orifices. 1-3 The case presented here is an example of a complete type in the classification of Trowitzsch and colleagues 2 and of a central type in the classification of Cascos, Rabago, and Sokolowski. 3 In the majority of isolated cases of DOMV, the second orifice is found as an accessory orifice, which is the cause of mitral regurgitation, s'4 For this type of accessory orifice, simple closure has been the choice to correct mitral regurgitation. 4 Mitral regurgitation associated with isolated DOMV with two equal orifices as in our case has rarely been described in previous literature. 5 Because no cleft was identified at operation, the choices of treatment seemed to be repair or closure of the valve. In a case with two equal orifices, however, closure of one orifice might produce acute diminution of the mitral valve area leading to a stenotic condition. 6 In addition, closure of the orifice might possibly cause deformity at the fibrous bridging tissue, leading to incompetence of another intact orifice. Considering the possible problem in closure of the orifice and the finding of a torn chorda located only at the posterior leaflet, valve repair was chosen in our case. The