14th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 2000

Jan. 29 - Feb. 5, 2000
Marilleva, Trento, Italy

RT-84

Left ventricular performance in right ventricular outflow tract pacing: a comparison with right ventricular apex pacing

Maria Cristina Porciani, Luigi Padeletti, Antonio Michelucci, Andrea Colella, Alessandro Costoli, Andrea Chelucci, Paolo Pieragnoli, Silvio Vena, Cristina Ciapetti, Alessandra Sabini, Letizia Giurlani, Gabriele Demarchi, Gian Franco Gensini.
Institute of Internal Medicine and Cardiology, University of Florence, Florence, Italy

Abstract

BACKGROUND. Previous studies have reported controversial findings about hemodynamic effects of right ventricular outflow tract (RVOT) pacing. Whether this site of stimulation is better than the traditional right ventricular apex (RVA) is still an open question. RVA pacing induces widening of QRS complex and interventricular asynchrony. In RVOT pacing the QRS is narrower, but information about interventricular asynchrony is lacking.

METHODS. Ten pts with chronic atrial fibrillation high-degree AV block or total AV block induced by RF ablation underwent a DDD chamber implantation. A screw-in lead was positioned in the RVOT and was connected to the atrial port of the device. A tined ventricular lead was positioned in the RVA and was connected to the ventricular port of the device. This configuration allowed to pace separately the two sites (AAIR or VVIR). Pts were randomized to RVA or RVOT pacing and after three months the mode of pacing was crossed-over. The following echo-Doppler parameters were evaluated: QRS duration, cardiac output (CO), isovolumetric relaxation time (IVRT), right and left electromechanical delay (RVED and LVED), interventricular delay (IVD) as the difference between LVED and RVED.

RESULTS. RVOT pacing compared to RVA pacing significantly reduces: QRS duration (157±17 vs 183±17, p<0.01) IVRT (82±29 vs 110±32, p<0.01), LVED (165±21 vs 181±25, p<0.01), IVD (20±15 vs 40±19, p<0.01). RVOT pacing significantly increases CO (5.8±0.9 vs 4.6±0.7).

CONCUSIONS. Our data show that RVOT pacing decreases QRS duration, reduces IVRT and induces an earlier contraction of the left ventricle decreasing the interventricular delay. A more normal activation sequence and a more simultaneous activation of right and left ventricle induce the improvement of diastolic and sistolic LV function.

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