Right Bundle Branch Block and Electromechanical Coupling of the Right Ventricle: An Echocardiographic Study

A growing body of evidence suggests that the presence of a right bundle branch block (RBBB) is a negative prognostic indicator in patients with and without preexisting heart disease. Even though electromechanical activation of the right ventricle (RV) in patients with RBBB and pulmonary hypertension (PH) has been investigated; a direct comparison of the presence of RBBB, on the duration of RV mechanical systole using echocardiography has not been studied.

In this retrospective study, we analyzed the echocardiograms of 40 patients by measuring the magnitude and timing of tricuspid annulus plane systolic excursion (TAPSE) and tricuspid annulus systolic velocity (TA S'). Patients were selected to form four groups of ten patients based on the presence or absence of RBBB and PH to determine if RBBB has any effect on the time-to-peak of TAPSE or TA S', which for our purposes serves as a measure of duration of RV mechanical systole.

Our results demonstrate that RBBB leads to a measurable prolongation of TAPSE and TA S' in patients without PH. Time-to-peak of TAPSE or TA S' was not significantly prolonged in patients with PH.

The results of this pilot study show that RV mechanical systole is prolonged in patients with RBBB, and the addition of PH attenuates this change. Additional prospective studies are now required to elucidate further the electrical and mechanical dyssynchrony that occurs as a result of RBBB, and how these new echocardiographic measurements can be applied clinically to risk stratify patients with RBBB and PH.