Left Ventricular Outflow Tract Obstruction

Abstract

Left ventricular outflow tract obstruction (LVOTO) accounts for 3.5-10% of all congenital heart defects [1, 2], with the majority of patients being male. LVOTO occurs at the valvar (70%), subvalvar (14%), and supravalvar (8%) levels, and several levels of obstruction often coexist (8%) [3]. LVOTO may be further compounded by other left-sided anomalies (small left atrium, abnormal mitral valve, small- or even hypoplastic - left ventricle (LV), aortic coarctation (CoA), or interrupted aortic arch) [4]. Often seen in this context is Shone’s complex - a combination of a parachute mitral valve, supra-annular mitral ring, subaortic stenosis, and CoA [5]. Ventricular septal defects, abnormal attachments of the mitral or tricuspid valve apparatus, and pulmonary venous anomalies may coexist with LVOTO. Critical LVOTO presents as shock in the early neonatal period, while less severe defects may only become clinically significant later in childhood, or even remain silent into adulthood [6].