Gabriele Vicedomini, Salvatore Rosanio, Giuseppe Oreto*, Carlo Meloni, Adriano Salvati, Stefano Bianchi, Cosimo Dicandia, Patrizio Mazzone, Monica Tocchi, Julio Spinelli**, Jiang Ding**, Luciano Sallusti, Sergio Chierchia, Carlo Pappone.
Department of Cardiology, Hospital S. Raffaele, Milan, *University of Messina, Italy, **Congestive Heart Failure Research Group, Guidant Corp., St.Paul, USA
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Cardiac pacing is a promising therapy for patients with
severe congestive heart failure (CHF) and LBBB1-3. Although the atrioventricular (AV) delay is an important
determinant of ventricular filling and pacing response, the pacing chamber has been recognized to
influence the efficiency of pump function. Contradictory acute and long-term clinical results have been
reported with atrial-synchronous right ventricular pacing using short AV delays4,5, whereas more
consistent and positive data have been presented when pacing either in the left ventricle (LV) or in
both the right and left ventricles1-3,6. Experimental studies have demonstrated that pacing at different
sites in the LV or performing a combined stimulation of multiple LV sites may influence the magnitude of
ventricular function response7,8. To date, however, no study has directly compared, in the same patients,
the hemodynamic effects of specific LV pacing sites, nor has attempted pacing 2 sites simultaneously.
The present study tested the following hypotheses: 1) pacing the LV base (B) at a posterior or
posterolateral location (the area of latest LV activation in the vast majority of patients with LBBB)6,9
yields comparable or better hemodynamic effects than the most commonly paced LV lateral free wall
(FW); 2) pacing both sites simultaneously (Dual-site-site) provides for faster ventricular activation,
expressed by shorter QRS duration, and possibly, greater LV function improvement than single-site
pacing.
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