A Giant Blood Cyst of Mitral Valve Resulting in Severe Left Ventricular Outflow Tract Obstruction

Abstract

Blood cysts of the papillary muscle of the mitral valve are rare in adults. These cysts are thin-walled, lined by flattened and cobblestone-shaped epithelium, and filled with nonorganized blood. Blood cysts are often asymptomatic, and a case resulting in severe left ventricular outflow tract obstruction and valvular dysfunction successfully treated by surgery has not been reported before. A 32-year-old man presented to the hospital with a 1-year history of chest pain and four episodes of syncope. Cardiac examination revealed a loud, harsh ejection systolic murmur throughout the precordium but greatest at the left sternal edge. Transthoracic echocardiography showed a giant mass (4.6 × 2.6 cm) with an echolucent center within the left ventricular cavity (Fig 1A-1 [AA = ascending aorta; LA = left atrium; LV = left ventricle; MV = mitral valve]). It seemed to be attached to the anterior leaflet of the mitral valve (A2). In systole, the mass prolapsed into the left ventricular outflow tract with a turbulent high-velocity systolic jet (4.9 m/second) and severe mitral regurgitation (Fig 1A-2). Left ventricular contrast echocardiography showed a giant cyst between the anterior papillary muscle of the mitral valve and the chordae tendineae (Fig 1A-3 [MI = mitral insufficiency). An emergency operation was performed with cardiopulmonary bypass for intractable chest pain. During the procedure, a smooth, oval, bluish mass (4.5 × 4 cm) was found attached by a stalk to the anterior papillary muscle of the mitral valve (Fig 1B [AML = anterior mitral leaflet; PM = papillary muscle]). The papillary muscle and anterior leaflet of the valve were excised to ensure complete clearance. In addition, a 31-mm St. Jude prosthesis (St. Jude Medical, Saint Paul, MN) was inserted. The postoperative recovery was uneventful, and the patient was symptom free and working full time during follow-up. The histopathologic examination showed a blood-filled cyst with a cyst wall composed of fibrous tissue (Fig 1C). This work was supported by 2018 Wuhan Young & Middle-Aged Medical Backbone Training Program; Health and Family Planning Commission of Wuhan municipality scientific research project (WX17Q35).