Induction of LBBB decreased the time delay between LV and RV pressure upslopes from -6.9 ms to -33.9 ms (P<0.05), while LV apex pacing increased it up to +20.9 ms (P<0.05).
Does LV apex pacing improve mechanical interventricular asynchrony in a dog model of induced LBBB?
The time delay between the upslope of LV and RV pressure signals (DeltaT(up)) is a reliable measure of mechanical interventricular asynchrony that can quantify the effects of LBBB and ventricular pacing.
Absolute Event Rate: -33.9% vs -6.9%
p-value: p=< 0.05
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.
Verbeek et al. (Tue,) conducted a other in Left bundle branch block (LBBB) (n=12). LBBB induction and LV apex pacing vs. Baseline (before LBBB induction) was evaluated on Time delay between the upslope of the LV and RV pressure signals (DeltaT(up)) (p=< 0.05). Induction of LBBB decreased the time delay between LV and RV pressure upslopes from -6.9 ms to -33.9 ms (P<0.05), while LV apex pacing increased it up to +20.9 ms (P<0.05).