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
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Since the introduction of cardiac pacing the
right ventricular apex (RVA) has been considered the elective site for permanent
stimulation: this choice was suggested by practical advantages such as easy placement
of leads, good fixation, low thresholds, rather than particular haemodynamic benefit.
However the RVA stimulation induces an anomalous sequence of activation and
contraction with consequent haemodynamically adverse effects. As early as 1925,
Wiggers1 reported that in intact dog models, artificial stimulation of the right ventricle
produced a less effective ventricular contraction than activation through the normal
conduction system. The greater the amount of muscle activated before activation of
the His-Purkinje system, the greater the degree of dyssynchrony and the weaker the
contraction.
In the last years right ventricular outflow tract (RVOT) pacing (RVOTP) has been
proposed to avoid these effects and improve cardiac function.
Whether RVOT pacing is better than traditional pacing is still an open question: the
results are discordant and the mechanisms by which RVOT pacing provides
hemodynamic benefit is still not well known.
In theory pacing at RVOT site because of its proximity to His bundle, could involve the
normal conduction system and lead to a more physiologic sequence of activation and
a more sincronous contraction of left and right ventricles.
The aim of our study was:
1) to confirm the haemodynamic benefit in RVOT pacing versus RVA pacing;
2) to demonstrate a reduction of interventricular delay.
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