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A 20 year old man presented with dyspnoea on exertion class III. Clinically he was diagnosed to have severe mitral regurgitation, possibly caused by rheumatic heart disease. The x ray revealed cardiomegaly with left atrial enlargement, and pulmonary venous and arterial hypertension. The ECG suggested left atrial overload with left ventricular hypertrophy.
He underwent transthoracic two dimensional echocardiography with colour Doppler study which revealed multilobulated cystic spaces in the left atrial cavity, with colour flow within these. The mitral valve was thin and there was severe mitral regurgitation. To define the anatomy further, transoesophageal echocardiography was performed which demonstrated cystic structures as before (below left). A communication between the left ventricle and one of these cysts was clearly seen just below the posterior mitral leaflet (below centre). A to-and-fro flow was seen on colour Doppler. With these findings the patient was diagnosed as having a submitral aneurysm of the left ventricle with severe mitral regurgitation. On cardiac catheterisation, there was moderate pulmonary arterial and pulmonary venous hypertension. Left ventricular angiogram in right anterior oblique view demonstrated filling of a multilobulated structure, close to the left atrium (below right). Severe mitral regurgitation was also confirmed.
Submitral aneurysm is a rare cardiac pathology mostly seen in African countries, particularly in the black population. It is considered to be a false aneurysm caused by a congenital defect in the posterior portion of the mitral annulus. Other aetiologies such as tuberculosis, Takayasu arteritis, and mitral valve endocarditis have been proposed. Although it can present rarely with life threatening complications such as ventricular tachycardia caused by compression of the left main coronary artery, the most common presentation is as severe mitral regurgitation.
Echocardiography usually shows it as a subpericardial echo-free space below the mural leaflet of the mitral valve, which communicates with the ventricular cavity. Our case presented with interesting echocardiographic features, not reported previously.