Double-Orifice Mitral Valve Associated with Bicuspid Aortic Valve and Primary Pulmonary Vein Stenosis.

Introduction

A 67-year-old man with severe bicuspid aortic valve (BAV) stenosis was referred for transcatheter aortic valve replacement. Cardiac computed tomographic angiography followed be transesophageal echocardiography revealed a double-orifice mitral valve (DOMV) caused by an accessory scallop fusing the mitral leaflets. The point of fusion was more toward the anterolateral commissure, causing asymmetric orifices. The patient was also found to have primary left upper pulmonary vein (PV) stenosis. We herein present this case and review the literature for similar cases.

Case Presentation

A 67-year-old man with a history of usual interstitial pneumonia was referred to our institution after transthoracic echocardiography showed a BAV and severe aortic stenosis (Video 5). Echocardiography had been ordered to evaluate for progressive shortness of breath out of proportion to the patient's underlying lung pathology. Cardiac computed tomographic angiography followed by transesophageal echocardiography revealed the anterior and posterior mitral valve (MV) leaflets to be fused near the centerline, resulting in a DOMV (Videos 1 and 2). This resulted in two unequal orifices, with the smaller one in the anterolateral commissure. At the point of leaflet fusion, an accessory scallop was noted to be attached to the middle scallop of the anterior leaflet (Figure 1B). The diastolic gradient across the MV was normal. There were multiple regurgitant jets caused by regurgitation across both MV orifices and the accessory scallop occupying the larger hole in different configurations throughout the cardiac cycle (Figure 1C) (Videos 3 and 4). In addition, the left upper PV was found to be stenosed, with prestenotic dilatation (Figure 2B). This was confirmed with increased velocities on Doppler interrogation (Figure 1D) (Video 6). The remainder of the PVs were normal.

Figure 1

Transesophageal echocardiogram. (A) Two-chamber view showing MV inflow through two separate orifices. (B) Three-dimensional view of the MV in diastole showing the double orifices and accessory scallop attached to A2 (arrow). (C) Three-dimensional view of the MV in systole showing multiple regurgitant jets caused by regurgitation across both MV orifices and the accessory scallop occupying the larger hole in different configurations throughout the cardiac cycle. (D) Doppler interrogation of the left upper PV showing abnormally high velocity (peak velocity 180 cm/sec). LA, Left atrium; LV, left ventricle.

Figure 2

Computed tomographic angiogram. (A, B) Orthogonal views of the stenotic left upper PV (red arrow) with prestenotic dilatation. (C) View of the MV in diastole showing the two orifices and the accessory scallop (black arrow). PA, Pulmonary artery.

Discussion

DOMV is a rare condition (present in 1% of patients with congenital heart disease) that is characterized by the presence of two separate orifices of the MV, each with an independent chordal attachment to the papillary muscles. Isolated DOMV is very rare. DOMV is often found in association with other congenital cardiac anomalies, most commonly BAV., Obstructive left-sided lesions are present in 40% of patients, including aortic coarctations, subaortic stenosis, and Shone syndrome., When the smaller orifice is posteromedial, a common atrioventricular canal is present in 90% of patients, whereas when the smaller orifice is anterolateral, as in our case, the atrioventricular canal is normal in 70% of patients. DOMV can be caused by a small strand of tissue connecting the anterior and posterior leaflets at the leaflet edge level (i.e., incomplete bridge type), a fibrous bridge dividing the atrioventricular orifice completely into equal or unequal parts (i.e., complete bridge type, as in our case), or an additional orifice with subvalvular apparatus occurring in the posterior commissure of the MV (i.e., hole type). DOMV often causes no hemodynamic abnormality and is detected as incidentally during surgery or necropsy. In some cases, the DOMV is regurgitant or, very rarely, stenotic. Surgical management of DOMV is not necessary, and the decision for surgical intervention depends on the associated cardiac anomalies and degree of mitral regurgitation and/or stenosis.

The most common cause of PV stenosis in the current age is secondary to radiofrequency ablation during PV isolation for management of atrial fibrillation. Primary PV stenosis is rare and is associated with other cardiac defects in 50% of cases. The PV stenosis is usually not static, and postnatal worsening of stenosis may be caused by abnormal proliferation of unusual myofibroblastic cells. During fetal cardiac development, fusion of the PVs with the left atrium and cardiac valve formation occur through the final stages of embryogenesis, between days 28 and 50. The majority of complex congenital cardiac conditions develop during this period. Moreover, recent studies suggest that restricting blood flow into fetal cardiac chambers plays a role in abnormal valvulogenesis. To our knowledge, this is the first reported case of primary PV stenosis in association DOMV and BAV. At this point, it is unclear if this is a mere coincidence of association or a syndrome that will become more recognizable with the widespread adoption of new cardiovascular imaging modalities.