Cardiac Hemodynamics Abnormalities Induced by Intermittent Left Bundle-branch Block: A Case Report.

The left bundle-branch block (LBBB) is related to worsening cardiac performance. We describe a case of a patient with an intermittent left bundle-branch block who underwent biventricular pacemaker implantation. We noted a detrimental effect on the performance of her left ventricle with the presence of the LBBB as compared to the performance after she underwent biventricular pacing or after reversal of LBBB (i.e., native rhythm with narrow QRS). Her LBBB was accompanied by increased isovolumetric contraction time, longer pre-ejection period, and increased myocardial performance index (i.e., the Tei index) compared to her sinus rhythm with a narrow QRS complex with or under biventricular pacing.