title: Sequential versus simultaneous biventricular resynchronization for severe heart failure: evaluation by tissue Doppler imaging.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) by means of simultaneous biventricular pacing improves left ventricular systolic performance and synchrony in patients with heart failure and bundle-branch block. We used tissue tracking and 3D echocardiography to evaluate the impact of sequential CRT with individualized interventricular delay programming.
  
  
  RESULTS
  Twenty consecutive patients with severe heart failure and left bundle-branch block were included. Tissue tracking and 3D echocardiography were carried out before and on the day after pacemaker implantation. Eleven different interventricular delays were examined in each patient. Patients were reexamined after 3 months. Simultaneous CRT immediately reduced the extent of myocardium displaying delayed longitudinal contraction (DLC) from 48.6+/-16% to 23.2+/-13% (P<0.01) and increased left ventricular ejection fraction percentage (LVEF%) from 22.4+/-6% to 29.7+/-5% (P<0.01). However, optimum sequential CRT caused a further reduction in the extent of DLC from 23.2+/-13% to 11.1+/-7.2% (P<0.01), with a simultaneous increase in LVEF% (from 29.7+/-5% to 33.9+/-6%, P<0.01). Three months of optimum sequential CRT further improved LVEF% (from 33.6+/-6% to 38.6+/-7.2%, P<0.01). Tissue tracking detected the segments with DLC, and their location determined optimum interventricular delay programming. Compared with simultaneous CRT, sequential CRT increased diastolic filling time by 7+/-2.5%.
  
  
  CONCLUSIONS
  Compared with simultaneous CRT, sequential CRT significantly improves left ventricular systolic and diastolic performance. Tissue tracking can be used to select optimum interventricular delay during CRT.
authors.affiliation: Department of Cardiology, Aarhus University Hospital, Skejby Sygehus, Aarhus, Denmark. psogaard@dadlnet.dk
authors.forename: Peter
authors.initials: P
authors.lastname: Sogaard
authors.forename: Henrik
authors.initials: H
authors.lastname: Egeblad
authors.forename: Anders K
authors.initials: AK
authors.lastname: Pedersen
authors.forename: Won Yong
authors.initials: WY
authors.lastname: Kim
authors.forename: Bent O
authors.initials: BO
authors.lastname: Kristensen
authors.forename: Peter S
authors.initials: PS
authors.lastname: Hansen
authors.forename: Peter T
authors.initials: PT
authors.lastname: Mortensen
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000628:therapy; D015150:Echocardiography, Doppler / Q000379:methods*; D019560:Echocardiography, Three-Dimensional / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy*; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D009200:Myocardial Contraction; D010138:Pacemaker, Artificial