title: Timing of the left ventricular electrogram and acute hemodynamic changes during implant of cardiac resynchronization therapy devices.
abstract: OBJECTIVE
  To examine the relationship between timing of the left ventricular (LV) electrogram (EGM) and its acute hemodynamic effect on instantaneous change in LV pressure (LVdP/dt(MAX)).
  
  
  METHODS
  In 30 patients (mean = age 67 +/- 7.9 years) who underwent implant of cardiac resynchronization therapy systems, the right ventricular (RV) lead was implanted at the RV apex (n = 23) or RV septum (n = 7). The LV lead was placed in a posterior (n = 14) or posterolateral (n = 16) coronary sinus tributary. QRS duration, interval from Q wave to intrinsic deflection of the LV EGM (Q-LV), and interval between intrinsic deflection of RV EGM and LV EGM (RV-LV interval) were measured. The measurements were correlated with the hemodynamic effects of optimized biventricular (BiV) stimulation, using the Pearson correlation coefficient.
  
  
  RESULTS
  The mean LVdP/dt(MAX) at baseline was 734 +/- 180 mmHg/s, and increased to 905 +/- 165 mmHg/s during simultaneous BiV pacing, and to 933 +/- 172 mmHg/s after V-V interval optimization. The Pearson correlation coefficient R between QRS duration, the Q-LV interval, and the RV-LV interval at the respective LVdP/dt(MAX) was 0.291 (P = 0.66), 0.348 (P = 0.030), and 0.340 (P = 0.033).
  
  
  CONCLUSIONS
  Similar significant correlations were observed between the acute hemodynamic effect of optimized BiV stimulation and the Q-LV and the RV-LV intervals. However, individual measurements showed an 80-ms cut-off for the Q-LV interval, beyond which the increase in LVdP/dt(MAX) was <10%.
authors.affiliation: Department of Cardiology, Catharina Hospital, Eindhoven, the Netherlands. carlgr@cze.nl
authors.forename: Berry M
authors.initials: BM
authors.lastname: van Gelder
authors.forename: Albert
authors.initials: A
authors.lastname: Meijer
authors.forename: Frank A
authors.initials: FA
authors.lastname: Bracke
mesh_terms: D000368:Aged; D001794:Blood Pressure; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D009202:Cardiomyopathies / Q000175:diagnosis / Q000503:physiopathology* / Q000517:prevention & control*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000503:physiopathology* / Q000517:prevention & control*