Left Ventricular Outflow Obstruction

L eft ventricular outflow tract obstructions (LVOTOs) encompass a series of stenotic lesions starting in the anatomic left ventricular outflow tract (LVOT) and stretching to the descending portion of the aortic arch (Figure 1).Obstruction may be subvalvar, valvar, or supravalvar.These obstructions to forward flow may present alone or in concert, as in the frequent association of a bicuspid aortic valve with coarctation of the aorta.All of these lesions impose increased afterload on the left ventricle and, if severe and untreated, result in hypertrophy and eventual dilatation and failure of the left ventricle.LVOTOs are congenital in the vast majority of individuals younger than 50 years in the United States; some variants of subaortic obstruction are the exception.It is imperative to consider all patients with LVOTO at a high risk for developing infective endocarditis, and one should always institute appropriate measures for prophylaxis.The present article is intended as a contemporary review of the causes, manifestations, treatments, and outcomes of LVOTO; it will not address LVOTO in the pediatric population or genetic hypertrophic cardiomyopathy but will focus strictly on congenital malformations in the adult.