Congenital Left Ventricular Outflow Tract Obstruction

Abstract

Left ventricular outflow tract obstruction (LVOTO) is classified by the site of presentation into valvar, subvalvar, and supravalvar forms. This disorder affects multiple age groups, and success rates of operative therapies vary dramatically. In general, there is an obstruction to forward flow which increases afterload, and if untreated, can result in hypertrophy, dilatation, and eventual failure of the left ventricle. Valvar stenosis is the most common, and when present in infants, carries a high mortality rate. Subvalvar stenosis is much less common and may present as a discrete ring or a diffuse tunnel. Supravalvar stenosis is the least common and likewise has discrete and diffuse forms. These various forms of obstruction require surgical relief. Each operation must be tailored to the individual patient. Additionally, the possibility for recurrent stenoses after operation is always present. For these reasons, therapy and interventions directed toward relief of LVOTO are considered to be palliative, and lifelong patient follow-up is necessary. This chapter focuses mainly on subvalvar (subaortic) stenosis and supravalvar stenosis.