RT-25
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Atrial stimulation by means of
floating electrodes: evaluation of different pacing configurations
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Matteo Di Biase, Giovanni Luzzi,
Matteo Anaclerio, Daniela Casella, Maria Vittoria Pitzalis, Paolo Rizzon.
Istituto di Cardiologia, Universita degli Studi, Bari, Italy
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Abstract
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Background. The major limitation to
the widespread use of DDD pacing utilizing a single lead with floating atrial dipole is
the parasitic stimulation of the phrenic nerve and the consequent diaphragmatic
contraction, which is an intolerable side effect. The reduction of diaphragmatic
stimulation incidence could be achieved by maximizing the difference between atrial and
diaphragmatic thresholds mainly by lowering the atrial threshold utilizing different
pacing configurations. In this study, 4 different pacing configurations were tested with
the 830-S PHYMOS lead.
Subjects and methods. During pacemaker implantation of 14 patients
with atrioventricular block of different degrees and sites, atrial and diaphragmatic
thresholds were tested utilizing 4 different pacing configurations: A = monopolar via
proximal electrode; B = monopolar via distal electrode; C = bipolar with proximal
electrode as a negative one; D = bipolar with distal electrode as a negative one.
Results. Pacing configuration C was associated with atrial capture in
all patients and showed the lowest incidence of diaphragmatic contraction and the highest
difference between atrial and diaphragmatic thresholds (4 V), with mean values of 2.6 ±
0.64 and 6.8 ± 1.5 V, respectively.
Conclusions. Utilizing a 830-S PHYMOS lead, a bipolar atrial
stimulation, with proximal floating electrode as negative, is associated with the lowest
atrial pacing threshold, the highest difference between atrial and diaphragmatic
thresholds and the highest incidence of atrial capture. A careful set up of an implanted
pacemaker could be helpful in avoiding diaphragmatic stimulation by utilizing the
difference in atrial and diaphragmatic thresholds.
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Key Words
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Pacing
electrode configuration, DDD pacemakers, OA
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