Isolated cleft posterior mitral valve leaflet: an uncommon cause of mitral regurgitation

A 53-year-old woman with a history of hypertension was referredfor an echocardiogram by her primary care physician after anunspecified abnormal ECG. The echocardiogram showed normal leftventricular size and function; however, an isolated cleft posteriormitral valve leaflet was identified with concomitant bileafletprolapse and mild mitral regurgitation. She was subsequentlyreferred to a cardiologist for clinical evaluation. Cleft mitralvalve leaflet (CMVL) is an uncommon congenital cause of mitralregurgitation. Clefts, defined as slit-like holes or defects,are hypothesized to be a result of incomplete expression ofan endocardial cushion defect which most commonly involves theanterior mitral valve leaflet with a paediatric incidence of1:1340. Clefts affecting only the posterior mitral valve leafletare extremely rare with only four cases being reported in themedical literature. Important co-existing anomalies with eitherposterior and/or anterior CMVL include counterclockwise rotationof the papillary muscles, the presence of an accessory papillarymuscle or mitral valve leaflet, atrial septal defects, and mitralvalve prolapse. Regurgitation from CMVL can lead to importantphysiological and anatomical changes within the cardiac system.Regurgitation results from blood flow directly through the cleftitself or from malcoaptation from accessory chordae with orwithout papillary muscle distortion. Significant chronic mitralregurgitation elevates left atrial filling pressures and leadsto chamber enlargement and eccentric left ventricular hypertrophy.Early detection through two-dimensional echocardiography canprovide accurate anatomical images of the various mitral valvestructures and identify associated congenital anomalies. Earlysurgical correction is preferred before mitral regurgitationcauses unfavourable remodelling. Most mitral valve cleft defectscan easily be repaired by suturing the edges of the cleft. Ifa cleft resection leads to limited residual valve tissue, theleaflet of the mitral valve can be reconstructed using an autologouspericardial patch pre-treated with buffered glutaraldehyde.Posterior CMVL is an uncommon but clinically important causeof mitral insufficiency. Early recognition of this rare clinicalentity and possible co-existent anomalies can identify the patientswho would benefit from surgical intervention before compensatoryleft ventricular remodelling and contractile dysfunction develop.