title: Acute effects of biventricular pacing in heart failure patients with a normal ejection fraction and mechanical dyssynchrony.
abstract: OBJECTIVE
  We tested the acute effects of resynchronization in heart failure patients with a normal (>50%) left ventricular (LV) ejection fraction (HFNEF) and mechanical dyssynchrony.
  
  
  METHODS
  Twenty-four HFNEF patients (72 ± 6 years, 5 male) with mechanical dyssynchrony (standard deviation of electromechanical time delay among 12 LV segments >35 ms) were studied with temporary pacing catheters in the right atrium, LV, and right ventricle (RV), and high-fidelity catheters for pressure recording. Using selected atrioventricular (AV) intervals of 60, 90, 120, 150, and 180 ms to optimize transmitral flow during simultaneous biventricular pacing, the RV-LV (VV) interval was then evaluated at RV30, RV15, 0, LV15, LV30, and LV45 (RV or LV indicates which ventricle was paced first, the number indicates by how many ms).
  
  
  RESULTS
  During simultaneous pacing, longer AV intervals were associated with improved LV pressure-derivative minimums and increased aortic pressures (p < 0.05 vs. normal sinus rhythm). In the VV interval from RV30 to LV45, there was a graded increase in the aortic velocity time integral and a decrease in dyssynchrony during simultaneous or LV-first pacing (p < 0.05 vs. normal sinus rhythm).
  
  
  CONCLUSIONS
  For HFNEF patients with mechanical dyssynchrony, acute simultaneous biventricular or LV-first pacing with longer AV intervals reduced mechanical dyssynchrony and improved diastolic and systolic hemodynamics.
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan, ROC.
authors.forename: Yi-Chih
authors.initials: YC
authors.lastname: Wang
authors.forename: Chih-Chieh
authors.initials: CC
authors.lastname: Yu
authors.forename: Fu-Chun
authors.initials: FC
authors.lastname: Chiu
authors.forename: Vincent
authors.initials: V
authors.lastname: Splett
authors.forename: Ruth
authors.initials: R
authors.lastname: Klepfer
authors.forename: Kathryn
authors.initials: K
authors.lastname: Hilpisch
authors.forename: Chia-Ti
authors.initials: CT
authors.lastname: Tsai
authors.forename: Ling-Ping
authors.initials: LP
authors.lastname: Lai
authors.forename: Juey-Jen
authors.initials: JJ
authors.lastname: Hwang
authors.forename: Jiunn-Lee
authors.initials: JL
authors.lastname: Lin
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy; D058409:Cardiac Resynchronization Therapy Devices; D003971:Diastole; D005260:Female; D006325:Heart Atria / Q000503:physiopathology*; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000628:therapy*; D006352:Heart Ventricles / Q000503:physiopathology*; D006439:Hemodynamics; D006801:Humans; D008297:Male; D013318:Stroke Volume; D013599:Systole; D014463:Ultrasonography