title: Left ventricular resynchronization therapy in a canine model of left bundle branch block.
abstract: Positive responses to left (LV) and biventricular (BV) stimulation observed in heart failure patients with left bundle branch block (LBBB) suggest a possible mechanism of LV resynchronization. An anesthetized canine LBBB model was developed using radio frequency ablation. Before and after ablation, LV pressure derivative over time (dP/dt) and aortic pulse pressure (PP) were assessed during normal sinus rhythm with right ventricle (RV), LV, or BV stimulation combined with four atrioventricular delays in six dogs. In three more dogs, M-mode echocardiograms of septal and LV posterior wall motion were obtained before and after LBBB and during LV stimulation. LBBB caused QRS widening and hemodynamics deterioration. Before ablation, stimulation alone worsened LV dP/dt and PP. After ablation, LV and BV stimulation maximally increased LV dP/dt by 16% and PP by 7% (P < 0.001), whereas little improvement was observed during RV stimulation. M-mode echocardiogram showed that LBBB resulted in a paradoxical septal wall motion that was corrected by LV stimulation. In conclusion, LV and BV stimulation improved cardiac function in a canine LBBB model via resynchronization of LV excitation and contraction.
authors: Heart Failure Research Department, Guidant Corporation, St. Paul, Minnesota 55112, USA.
authors: Lili
authors: L
authors: Liu
authors: Bruce
authors: B
authors: Tockman
authors: Steven
authors: S
authors: Girouard
authors: Joseph
authors: J
authors: Pastore
authors: Greg
authors: G
authors: Walcott
authors: Bruce
authors: B
authors: KenKnight
authors: Julio
authors: J
authors: Spinelli
mesh_terms: D000818:Animals; D001011:Aorta / Q000503:physiopathology; D002037:Bundle-Branch Block / Q000628:therapy*; D004195:Disease Models, Animal; D004285:Dogs; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006439:Hemodynamics; D008297:Male; D009200:Myocardial Contraction; D014160:Transducers, Pressure; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology / Q000628:therapy*; D017725:Ventricular Pressure