Dynamic left ventricular outflow tract obstruction

Abstract

Left ventricular outflow tract (LVOT) obstruction is often clinically unrecognized unless echocardiographic assessment is performed. Its occurrence is favoured by anatomical factors (i.e. concentric or asymmetrical hypertrophy, excess tissue in mitral valve), hypovolemia and adrenergic stimulation and can occur in various conditions including postoperative setting (especially but not exclusively, after cardiac surgery), stress cardiomyopathy, and sepsis. A high flow in a narrow LVOT generates a Venturi effect in the LVOT which results in the attraction of the anterior mitral leaflet towards the interventricular septum causing LVOT obstruction. Not only this generates an intraventricular (left ventricle to LVOT) pressure gradient but can also be accompanied by mitral regurgitation that can sometimes be severe. Prompt echocardiographic assessment is warranted in order to adequately manage the patient. Typical echocardiographic findings include systolic aliased flow in LVOT on colour Doppler and dagger-shaped or double-peak Doppler flow in LVOT. The systolic anterior movement of the anterior leaflet of the mitral valve should be carefully searched. In some cases mitral regurgitation can be observed. Therapy may include fluid administration, weaning of adrenergic agents, and, whenever possible, beta-blockade administration.