Left Ventricular Outflow Obstruction

Abstract

Left 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. Figure 1. Artist’s rendering of the LVOTO lesions in sequence as viewed from a superolateral orientation. A, Gradient echo cardiac MR image as viewed from the frontal projection demonstrating flow acceleration at a site of supravalvar aortic stenosis (white arrow) in a patient with Williams syndrome. The black arrow identifies the level of the unrestricted aortic valve. B, Classic radiological signs of coarctation of the aorta: rib notching (white arrows) as seen on a posteroanterior chest x-ray in a patient with coarctation of the aorta. The rib notching is caused by erosion of the inferior rib margins by dilated pulsatile posterior intercostals collateral arteries. The black arrow points to the Figure 3 silhouette that …