P1720 Hammock mitral valve, a challenging echocardiographic diagnosis

Abstract

Abstract We report a 43 year-old female with a past TTE echocardiography of rheumatic valve disease performed in her district hospital , ( No clear symptomatology of rheumatic fever in the past). She was transferred to our tertiary hospital for elective cardiac surgery. Preoperative echocardiogram showed a non-dilated left ventricle with preserved contractility, mild-moderate left atrium enlargement with severe mitral regurgitation and basal displacement of papillary muscles and severe tricuspid regurgitation.All of it resembling a hammock mitral valve instead of former echocardiogram described as rheumatic valve disease. Preoperative cardiac study showed severe pulmonary hypertension with increased pulmonary vascular resistances. Preserved biventricular cardiac output and increased proto and telesystolic pressures. During surgery , ifindings were described as a mitral valve with a large papillary muscle inserted in the distal third of the left ventricle with none tendinous cords at the anterior leaflet and without cords in the posterior leaflet with an isolated papillary muscle with cords at A3 and P3 scallops, compatible with hammock mitral valve. A tendinous muscle/fibrous or fibromuscular band connecting the septum to the posterior wall of the left ventricle was described. Moreover over, there was an enlarged tricuspid ring with very short tendinous cords on the septal leaflet, although the leaflet was bigger than usual. Surgery consisted of resection of the mitral valve preserving A3 and P3 scallops with a 29mm Bicarbon Sorin mechanical mitral prosthesis and a 32mm Carpentier tricuspid ring implantation and pulmonary veins ablation combined with occlusion of left atrial appendage. After 112 minutes of cross-clamping time, the patient was weaned from cardiopulmonary bypass. She had important left ventricle dysfunction which improved with dobutamine and AAI pacemaker at 90lpm. Postoperative TEE showed moderate dysfunction of right ventricle, mild left ventricular dysfunction, moderate tricuspid regurgitation and a good functioning of the prosthesis. TTE before discharge showed good function of mitral valve prosthesis, good left ventricle function, mild tricuspid regurgitation, mild-moderate right ventricular enlargement, although less than preoperatively. Conclusion Congenital mitral valulophaty is a rare condition in the adulthood. The estimated prevalence is 0,5%. The hammock mitral valve is a more uncommon pathology which affects the mitral valve and subvalvular apparatus. This anomaly, was first described in 1967 and it is characterised by anomalous papillary muscles directly connected to the anterior mitral valve by a fibrous bridge without chordae tendineae in between them. This fibrous bridge hampers the opening and closure of the mitral valve. Diagnosis requires a high index of suspicion, both ultrasound studies and medical history, to avoid misdiagnosis. Abstract P1720 Figure.