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Dual chamber pacing (DDD) with short AV delay has first been
proposed in the early 90’s as an alternative therapy for severe drug refractory heart failure1. The mechanisms
of the beneficial effect have been attributed to an improvement of LV filling due to the resynchronization of
atrial contraction and to a reduction in presystolic mitral regurgitation, the latter being observed especially
in patients with first degree AV block2. However hemodynamic benefits of short AV delay dual chamber
pacing have not been observed by other investigators3-5.
Table I – Expectations from biventricular pacing12
- Restoration of both left and right ventricular
contraction
- Decrease in the lateral wall diskinesia
-
Better synchronization of the papillary muscle
contraction and decrease in the mitral regurgitation
-
Resynchronization of ventricular filling flows and
decrease in filling pressures
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Later, the ventricular activation sequence had been emphasized as the key point and alternative stimulation
modalities were proposed: RV outflow tract and/or RV multisite stimulation6-9. However, further studies
showed that for better resynchronization, left ventricle based pacing was indispensable10,11. Thus,
biventricular pacing has gained great interest and emerged as an alternative for patients with CHF
refractory to optimal drug therapy.
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