Left Ventricular Outflow Tract Obstruction

Left ventricular outflow tract obstruction (LVOTO) refers to the limitation of blood flow out of the left ventricle. The level of obstruction can be valvular, sub-valvular, or supravalvular. It can include anatomic stenotic lesions anywhere from left ventricle (LV) outflow to descending aorta. Hemodynamically, LVOTO has been defined as a peak instantaneous gradient at LV outflow of at least 30 mmHg, either at rest or on provocation.  While traditionally defined in patients with hypertrophic cardiomyopathy, LVOTO is known to have several causes.  LVOTO constitutes 6% of congenital heart diseases and in most cases, the cause of LVOTO is congenital.  It can occur in isolation or accompany other congenital heart diseases.  Dynamic LVOTO can also be seen in critically ill patients, whereby the use of inotropes in patients with intravascular volume depletion results in hypovolemia.  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.  
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