Objectives To determine the effects of interventricular pacing interval and left ventricular (LV) pacing site on ventricular dyssynchrony and function at baseline and during biventricular pacing, using tissue Doppler imaging.
MethodsUsing an angioplasty wire to pace the left ventricle, 20 patients with heart failure and left bundle branch block underwent temporary biventricular pacing from lateral (n=20) and inferior (n=10) LV sites at 5 interventricular pacing intervals: +80, +40, synchronous, -40 and -80ms.
Results LV ejection fraction (EF) increased (from 18 ± 8% to 26 ± 10%, p=0.016) and global mechanical dyssynchrony decreased (from 187 ± 91ms to 97 ± 63ms, p=0.0004) with synchronous biventricular pacing compared to unpaced baseline. Sequential pacing with LV pre-activation produced incremental improvements in EF and global mechanical dyssynchrony (p<0.0001 and p=0.0026 respectively), primarily as a result of reductions in inter LV-RV (p=0.0001) rather than intra LV (p=NS) dyssynchrony. Biventricular pacing from an inferior or lateral LV site were comparable (e.g. synchronous biventricular pacing- global mechanical dyssynchrony: lateral LV site 97± 63ms, inferior LV site 104 ± 41ms, p=NS; EF: lateral LV site 26 ± 10%, inferior LV site 27 &± 10%, p=NS). ECG morphology was identical during biventricular pacing via an angioplasty wire and a permanent lead.
Conclusions Sequential biventricular pacing with LV pre-activation most frequently optimises LV synchrony and EF. An inferior LV site offers a good alternative to a lateral site. Pacing via an angioplasty wire may be useful in assessing the acute effects of pacing.
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