RT-237
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Dual chamber pacing with
optimized AV delay in congestive heart failure patients: 6th month results of a randomized
study
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S. Mangiameli, D. Castelli, G.
Doria, P. Lo Giudice, G. Chiaranda and ISSC Group.
Divisione di Cardiologia, Ospedale Garibaldi, Catania, Italy
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Introduction
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Dual chamber pacing has been found to improve symptoms
and NYHA Class in patients with dilated cardiomyo-pathy and congestive heart failure1-3. Subsequently these results were partially confirmed4 or completely contradicted5,6,
probably because the results were derived from observational studies with small,
heterogeneous patient populations. In addition, it is unknown whether all subjects with
left ventricular systolic dysfunction respond to dual-chamber pacing or whether the
beneficial effect is limited to a select subgroup of patients. The hemodynamic mechanisms
of this "electrical" therapy may be resumed in three main physiopathologic
statements:
1) the reduction of mitral regurgitation. Sequential pacing with short AV interval
leads to an activated atrium during the expulsive stage of the left ventricle, thus
determining the reduction of the ventriculoatrial gradient, the diastolic mitral
regurgitation and the early mitral valve closure1,7;
2) a better utilization of the Frank-Starling mechanism obtained by restoring the
atrioventricular synchronization8;
3) a better sequence of the activation-relaxation induced by sequential pacing
compared with that realized by the normal conduction pathways3,4,9.
This mechanism may reduce the apical activation delay, that it's very pronounced in
dilated hearts, and, consequently, the wall stress.
From these previous statements it appears evident that only a small, select group of
patients may benefit from DDD pacing with shortened AV delay.
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Key Words
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Pacing - congestive heart failure
dual chamber pacing, optimized-programmed AV interval, dilated cardiomyopathy, Italian
Study on Stimulation in Cardiomyopathy/ISSC trial, left ventricular filling, OA
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