Supramitral obstruction of left ventricular inflow tract by supramitral ring

Abstract

Supramitral ring (SMR) is a rare developmental abnormality of the supravalvular area of the mitral valve which produces a variable degree of obstruction to left ventricular filling. The morphological substrate of SMR consists of a fibro-membranous ring which is adherent to the atrial aspect of the mitral valve leaflets. SMR is morphologically and embryologically distinct from the more common entity of cor triatriatum, which consists of an obstructive fibro-muscular membrane located within the left atrium proximal to the left atrial appendage. Surgical resection of SMR is usually effective as evident by the generally benign postoperative hemodynamic outcome. Coexistent mitral valvular lesions are usual but not typically severe in degree. © 2004 Elsevier Inc. All rights reserved.