Submitral Aneurysm: A Rare Cause of Complete Heart Block

Abstract

Subvalvular left ventricular (LV) aneurysms are rare and are of two types – subaortic and submitral. More commonly, they are submitral in position. Submitral aneurysms (SMAs) are most commonly located below posterior mitral leaflet (PML), whereas subaortic aneurysms are present below intermediate portion of the left aortic sinus. SMA was first described by Corvisart in 1812, and since then, only about 100–120 cases have been described worldwide. Aneurysmal dilatation in submitral position behind PML that communicates with left ventricle helps in making the diagnosis. Color Doppler echocardiography reveals the severity of mitral regurgitation. Transesophageal echocardiography and contrast-enhanced computed tomography (CT) are helpful in diagnosis in cases of acute rupture of SMA, and contrast-enhanced CT helps in evaluation of coronaries. Surgical resection is the definitive treatment for these aneurysms. Our special case presented with complaints of giddiness and presyncope and was diagnosed as complete heart block on electrocardiogram and was then diagnosed as having a large SMA on two-dimensional echocardiogram with LV dysfunction. Usually, SMAs present with dyspnea, pansystolic murmurs due to mitral regurgitation, fever secondary to infective endocarditis, or as thromboembolism. However, this patient presented symptoms of complete heart block. To conclude, SMA should be considered in differential diagnosis of mitral regurgitation with LV dysfunction and heart failure in young patients. Although complete heart block is uncommon in these patients, it should be kept in mind.