title: Morphology of the RV electrogram during LV pacing is related to the hemodynamic effect in cardiac resynchronization therapy.
abstract: BACKGROUND
  Biventricular (BiV) pacing and left ventricular (LV) pacing both improve LV function in patients with heart failure and LV dyssynchrony. We studied the hemodynamic effect of the atrioventricular (AV) interval and the associated changes in the right ventricular (RV) electrogram (EGM) during LV pacing and compared this with the hemodynamic effect of optimized sequential BiV pacing.
  
  
  METHODS
  In 16 patients with New York Heart Association (NYHA) class II to IV, sinus rhythm with normal AV conduction, left bundle branch block (LBBB), QRS > 130 ms, and optimal medical therapy, the changes in RV EGM during LV pacing with varying AV intervals were studied. The hemodynamic effect associated with these changes was evaluated by invasive measurement of LVdP/dt(max) and compared with the result of optimized sequential BiV pacing in the same patient.
  
  
  RESULTS
  All patients showed electrocardiographic fusion during LV pacing. The morphology of the RV EGM showed changes in the RV activation that indicated a shift in the extent of fusion from LV pacing. These changes were associated with significant changes in LVdP/dt(max). Baseline LV dP/dt(max) was 734 +/- 177 mmHg/s, which increased to 927 +/- 202 mmHg/s (P<0.0001) with optimized LV pacing and to 920 +/- 209 mmHg/s (P<0.0001) with optimized sequential BiV pacing.
  
  
  CONCLUSIONS
  The RV EGM is a proper indicator for intrinsic activation over the right bundle during LV pacing and reveals the transition to fusion in the RV EGM that is associated with a decrease in LVdP/dt(max). The hemodynamic effect of optimized LV pacing is equal to optimized sequential BiV pacing.
authors.affiliation: Bakken Research Center, Maastricht, The Netherlands. carlgr@cze.nl
authors.forename: Berry M
authors.initials: BM
authors.lastname: van Gelder
authors.forename: Frank A
authors.initials: FA
authors.lastname: Bracke
authors.forename: Albert
authors.initials: A
authors.lastname: Meijer
authors.forename: Art
authors.initials: A
authors.lastname: Pilmeyer
authors.forename: Nico H J
authors.initials: NH
authors.lastname: Pijls
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002303:Cardiac Output, Low / Q000175:diagnosis* / Q000517:prevention & control*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000517:prevention & control*; D018497:Ventricular Dysfunction, Right / Q000175:diagnosis* / Q000517:prevention & control