Patterns of Left Ventricular Contraction in Strain Vector Space Related to Bundle Branch Block with Heart Failure by Speckle-Tracking Echocardiography

The aim of this research is to study bundle branch block (BBB)-related patterns of radial strain in the left ventricles of patients with heart failure by speckle-tracking echocardiography. Twenty-seven left-BBB (LBBB), 10 right-BBB (RBBB), and 11 narrow QRS-complexes (non-BBB) patients and 11 healthy subjects were assessed. Strain fractions used to quantify thickening-during-systole and thinning-during-diastole, and timing parameters defined as time to onset-of-thickening and peak-strain were measured. Principal strain vectors were conducted on the fractions and parameters to analyze mechanical discoordination and dyssynchrony. Heart failure patients show a significantly greater extent of discoordination and dyssynchrony compared with healthy subjects. Significant differences between the LBBB and RBBB groups are demonstrated by deflection, a spatial characteristic of myocardial coordination. New information provided by these findings can provide a better understanding of BBB-related mechanisms of myocardial coordination and may be useful in improving patient selection, electrode placement and subsequent outcomes for cardiac resynchronization therapy. (E-mail: chanhl@mail.cgu.edu.tw)