RT-120
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"Optimal"
atrioventricular delay in physiological pacing: assessment by echo-doppler study of common
carotid artery flow and ergospirometric evaluation
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Gherardo Gherarducci, Stefano
Viani, Paolo Caravelli, Flavio Buttitta, Alberto Balbarini, Mario Mariani.
Cardiovascular and Pulmonary Department, University of Pisa, Italy
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Abstract
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Background. We investigated the role
of echo-doppler evaluation of common carotid artery flow in programming the optimal
atrioventricular delay in patients with pacemakers which maintain atrioventricular
synchronization.
Methods. Twenty-one patients, implanted with VDD(R) single-lead
pacemakers because of impaired atrioventricular conduction, were studied during VDD pacing
at various atrioventricular intervals (75, 100, 150, 200, 250) and VVI pacing mode. We
measured Doppler velocity flow curves at right common carotid artery and defined optimal
atrioventricular delay that associated with the highest velocity-time integral value.
Subsequently the patients performed an ergospirometric test both in VDD, at optimal
atrioventricular delay, and VVIR pacing mode.
Results. We observed a large interindividual variability of optimal
atrioventricular delay in atrial sensed-ventricular paced stimulation. However the mean
value of flow-velocity integral at optimal atrioventricular delay was significantly higher
than the value associated with the most unfavourable one (36.7 ± 9 cm vs 29.3 ± 6 cm; p
< 0.02), with the nominal delay setting (36.7 ± 9 cm vs 33 ± 7.8 cm; p < 0.05) and
with VVI pacing mode (36.7 ± 9 cm vs 29.7 ± 8.3 cm; p < 0.02). Moreover atrial
sensed-ventricular paced stimulation at optimal atrioventricular delay provided a
statistically significant increase of oxigen consumption (14 ± 3.9 ml/kg/min vs 9.6 ±
4.5 ml/kg/min; p < 0.01) and exercise duration (403 ± 132 sec vs 300 ± 121 sec; p
< 0.05) at anaerobic threshold in respect to VVIR pacing mode.
Conclusions. Optimal atrioventricular interval shows a large
interindividual variability in atrial sensed-ventricular paced stimulation, consequently
empirical or nominal setting seems to be quite unsatisfactory. Atrioventricular
synchronization, at the single best programmable delay, gives an additional contribution
to effort performance in respect to ventricular rate increase. Echo-doppler measurement of
common carotid artery flow may be a useful, non-invasive method to choose the best
atrioventricular delay in these patients both at rest and during exercise.
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Key Words
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Pacing assessment – follow-up
atrial sensed-ventricular paced stimulation, optimal atrioventricular delay, Doppler
echocardiography, OA
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