title: Quantification of interventricular asynchrony during LBBB and ventricular pacing.
abstract: The quantification of mechanical interventricular asynchrony (IVA) was investigated. In 12 dogs left bundle branch block (LBBB) was induced by radio frequency ablation. Left ventricular (LV) and right ventricular (RV) pressures were recorded before and after induction of LBBB and during LBBB + LV apex pacing at different atrioventricular (AV) delays. Four IVA measures were validated using computer simulations on experimentally obtained pressure signals. The most robust measure for IVA was the time delay between the upslope of the LV and RV pressure signals (DeltaT(up)), estimated by cross correlation. The induction of experimental LBBB decreased DeltaT(up) from -6.9 +/- 7.0 ms (RV before LV) to -33.9 +/- 7.6 ms (P < 0.05) in combination with a significant decrease of LV maximal first derivative of pressure development over time (dP/dt(max)). During LV apex pacing, DeltaT(up) increased with decreasing AV delay up to +20.9 +/- 14.6 ms (P < 0.05). Interventricular resynchronization (DeltaT(up) = 0 ms) significantly improved LV dP/dt(max) by 15.1 +/- 5.9%. QRS duration increased significantly after induction of LBBB but did not change during LV apex pacing. In conclusion, DeltaT(up) is a reliable measure of mechanical IVA, which adds valuable information concerning the nature of asynchronous activation of the ventricles.
authors.affiliation: Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands. x.verbeek@fys.unimaas.nl
authors.forename: Xander A A M
authors.initials: XA
authors.lastname: Verbeek
authors.forename: Kevin
authors.initials: K
authors.lastname: Vernooy
authors.forename: Maaike
authors.initials: M
authors.lastname: Peschar
authors.forename: Theo
authors.initials: T
authors.lastname: Van Der Nagel
authors.forename: Arne
authors.initials: A
authors.lastname: Van Hunnik
authors.forename: Frits W
authors.initials: FW
authors.lastname: Prinzen
mesh_terms: D000818:Animals; D002036:Bundle of His / Q000503:physiopathology*; D002037:Bundle-Branch Block / Q000503:physiopathology*; D003198:Computer Simulation; D004285:Dogs; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D008297:Male; D008955:Models, Cardiovascular; D010138:Pacemaker, Artificial; D016276:Ventricular Function