Transient and dynamic left ventricular outflow tract obstruction - a literature review

Abstract

Left ventricular outflow tract obstruction (LVOTO) refers to the interference of the ejection of blood flow from the left ventricle to the aorta and is defined by a pressure gradient equal or greater than 30 mmHg. Its exact prevalence in the general population is unknown, however, it is considered a relevant and underdiagnosed cause of hypotension and hemodynamic deterioration in certain clinical scenarios. Traditionally, dynamic LVOTO is associated with hypertrophic cardiomyopathy (HCM), as this is its most common cause, present in approximately 2/3 of patients diagnosed with HCM. However, it has also been described in both anatomically predisposed individuals (with left ventricular hypertrophy, septal hypertrophy, and sigmoid septum), acute myocardial infarction and in structurally normal hearts, associated with various clinical situations, such as takotsubo cardiomyopathy, catecholaminergic overload, by exogenous administration, or in the presence of a pheochromocytoma, and as well as in the setting of change in volume status due to dehydration/ volume depletion. This literature review aims to integrate the most common clinical scenarios associated with LVOTO, other than HCM, to elucidate the pathophysiology behind this phenomenon and to describe the best approach to the diagnosis, management and treatment options for these specific subsets of patients.