Double-orifice mitral valve - echocardiographic findings.

BACKGROUND Double-orifice mitral valve (DOMV) is a rare congenital malformation characterised by the presence of two orifices in the left atrio-ventricular valve area, each having an independent chordal attachment to the papillary muscle. AIM To establish the echocardiographic features and incidence of DOMV in patients undergoing an echo study in a tertiary referral centre. METHODS We carried out a retrospective review of 215,193 echocardiographic studies in 79,919 patients performed between 1993 and 2006. Transthoracic echocardiographic examinations (TTE) of nine patients with DOMV (six female, mean age 37.9 years, range 8-59) were analysed. RESULTS In six patients, the complete bridge type of DOMV was recognised, two patients had a duplicate mitral valve, and one had the hole type. In all cases, mild to moderate mitral regurgitation was present. Moderate to severe mitral stenosis was diagnosed in five cases and was associated with the complete bridge type. In four patients, ostium primum atrial septal defect was present. The TTE was sufficient to define the type, anatomy and associated lesions in seven cases. In two patients, TEE was essential to establish the diagnosis. CONCLUSIONS Transthoracic echocardiographic examination is a reliable, and in most cases sufficient, means of diagnosing DOMV and determining its type. The DOMV as a cause of symptomatic mitral valve disease is seen in middle-aged/elderly patients. The incidence of double-orifice mitral valve in the adult tertiary referral echocardiographic laboratory is estimated at 0.01%.