title: Further deterioration of LV ejection fraction and mechanical synchrony during RV apical pacing in patients with heart failure and LBBB.
abstract: Electrocardiographic left bundle branch block (LBBB) may be due to intrinsic disease of the left bundle branch or induced by right ventricular apical (RVA) pacing. Prior reports clearly delineate the derogatory impact of LBBB on left ventricular (LV) mechanical function but suggest equivalent impact between varieties. We hypothesized that their effects were disparate and performed a within-patient comparison to test this notion. Patients (n = 20) with heart failure, intrinsic LBBB, and an implanted pacing device with right atrial and RVA leads were studied. Each patient underwent transthoracic three-dimensional speckle-tracking echocardiography during atrial pacing (intrinsic LBBB) and short atrioventricular delay atrial-RVA pacing, and these studies were compared. Relative to intrinsic LBBB, RVA pacing-induced LBBB produced greater intra-LV and interventricular dyssynchrony, a deterioration in LV function, and a shift in the site of latest activation. In patients with heart failure and LBBB, acute RVA pacing induces greater mechanical dyssynchrony and further impairs LV function.
authors.affiliation: Heart and Vascular Institute, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Ludwig
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Mati
authors.initials: M
authors.lastname: Friehling
authors.forename: John
authors.initials: J
authors.lastname: Gorcsan
authors.forename: David
authors.initials: D
authors.lastname: Schwartzman
mesh_terms: D000200:Action Potentials; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects* / Q000379:methods; D019560:Echocardiography, Three-Dimensional; D004562:Electrocardiography; D006329:Heart Conduction System / Q000503:physiopathology*; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D013997:Time Factors; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000503:physiopathology*; D016277:Ventricular Function, Left; D016278:Ventricular Function, Right