title: Right ventricular contractility as a measure of optimal interventricular pacing setting in cardiac resynchronization therapy.
abstract: OBJECTIVE
  The aim of the present study was to assess whether right ventricular (RV) contractility can be used for optimization of the interventricular (VV) interval and to study the acute hemodynamic effect of different VV intervals on right and left ventricular (LV) contractility in patients referred for cardiac resynchronization therapy (CRT).
  
  
  RESULTS
  Intracardiac LV and RV dP/dt were measured with a 0.014-in. sensor-tipped pressure guidewire during pacing at nine different VV intervals ranging from +80 ms (LV pre-excitation) to -80 ms (RV pre-excitation) in 26 patients who received a biventricular pacemaker. No correlation was found between the optimal VV intervals identified by maximum LV dP/dt and RV dP/dt, which were identical in only seven cases (27%). Only when testing slightly broader intervals (+/-20 ms) was there a statistically significant correlation (P= 0.037) between the optimized VV intervals. In the majority of patients (58%) either LV or RV pre-excitation was superior to simultaneous pacing according to LV dP/dt(max) measurements.
  
  
  CONCLUSIONS
  RV dP/dt(max) failed to identify the optimal VV interval when compared with LV dP/dt(max) and can therefore not be recommended for VV optimization in CRT patients.
authors.affiliation: Department of Cardiology, Uppsala University Hospital, S-751 85 Uppsala, Sweden. elena.sciaraffia@akademiska.se
authors.forename: Elena
authors.initials: E
authors.lastname: Sciaraffia
authors.forename: Helena
authors.initials: H
authors.lastname: Malmborg
authors.forename: Stefan
authors.initials: S
authors.lastname: Lönnerholm
authors.forename: Per
authors.initials: P
authors.lastname: Blomström
authors.forename: Carina
authors.initials: C
authors.lastname: Blomström Lundqvist
mesh_terms: D002304:Cardiac Pacing, Artificial / Q000379:methods*; D005260:Female; D006801:Humans; D008365:Manometry / Q000379:methods*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000209:etiology / Q000517:prevention & control*; D013813:Therapy, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome; D018497:Ventricular Dysfunction, Right / Q000150:complications* / Q000175:diagnosis*