Assessment of septal motion abnormalities in left bundle branch block patients using computer simulations

Abstract

Septal Flash (SF) is a rapid leftward – rightward motion of the septal wall during the isovolumic contraction phase that is frequently but not always observed in heart failure patients with left bundle branch block (LBBB). The goal of the present study is to evaluate the feasibility of detecting SF by assessing septal curvature both in patients with LBBB using MRI and in simulations using the CircAdapt model of the heart and circulation. In both patients and simulations, SF was characterized by a decrease of septal wall curvature and septum to lateral wall distance, followed by a rapid increase prior to aortic valve opening. Additionally, computer simulations revealed that SF can be explained by an intra-left ventricular (septal-to-lateral wall) activation delay. Reducing contractility in the left ventricular free wall abolished the rightward SF motion in LBBB. This finding suggests that lack of SF may indicate co-morbidities that can result in nonresponse to cardiac resynchronization therapy.