Case Report

HOCM/Sigmoid septum: mechanism and management of the obstruction

Author: Marc Radermecker

In Hypertrophic Obstructive Cardiomyopathy Associated to Sigmoid Septum (HOCM/SS), the left ventricular outflow tract obstruction is a complex dynamic phenomenon where the asymmetric hypertrophy of the basal septum and associated anomalies of the mitral valve leaflets and subvalvular apparatus are less likely to explain per se the subaortic obstruction. It is our view that the closure of the aorto-mitral angle in this setting is paramount. It entails, for obvious geometric reasons, a bulging of the basal septum underneath the aortic valve and the misalignment between the LV and outflow/aortic root creates the path for an ejectional flow pattern, which may drag the mitral apparatus and promote obstruction by pushing the subvalvular apparatus and leaflets in the outflow tract. Via the presentation of a complex HOCM/SS case, the pertinent recent literature on this subject is summarized and the recommendations for interventional treatment are discussed. Even with close results, surgery appears to be more efficient in this setting.