Dynamic Left Ventricular Outflow Tract Obstruction - when to Intervene?

Abstract

Left ventricular outflow tract obstruction (LVOTO) in hypertrophic cardiomyopathy (HCM), most commonly is provoked by the contact between the hypertrophied basal interventricular septum (IVS) and the systolic anterior motion (SAM) of the anterior leaflet of mitral valve, during systole, thus narrowing the left ventricular outflow tract (LVOT). Several theories have been proposed to explain the occurrence of SAM and LVOTO, the “drag effect” theory is widely accepted. Despite SAM, one of the others morphological features that can contribute to LVOTO is an insertion of an accessory muscle bundle extending from the apex to the basal anterior septum of free wall of the left ventricle. In this case report we present a case of 71-year-old man with dyspnea and syncope, exercise induced, as a result of severe dynamic LVOTO. The LVOTO was a result of HCM, mostly affecting the basal IVS, with concomitant insertion of an accessory muscle bundle at the basal segment of IVS, that was additionally thickening the IVS, and SAM of the anterior mitral lealflet (AML), that were narrowing the LVOT and causing high LVOT gradients (86,3 mm Hg) at rest. The patient was symptomatic, he had dyspnea and syncope, exercise induced. The patient underwent a septal myectomy and mitral valve repair, which successfully reduced the gradients and relieved the patient of the symptoms.