Abstract 2665: Effects of Autonomic Interventions on Atrial Restitution Properties
Introduction: The action potential duration (APD) restitution hypothesis suggests that when cardiac tissue has a restitution curve with a slope >1, AP alternans and wave break may occur, leading to fibrillation. This study aimed to investigate the effects of autonomic interventions on the restitution properties on the atria.
Methods: In 8 open-chest dogs, multiple electrode catheters were sutured at multiple PV and atrial sites. The AP was recorded by an Ag-AgCl catheter. The restitution curve at each site was constructed by plotting each APD90 against the preceding diastolic interval at incremental atrial pacing rates (10ms steps) before and after vagal stimulation or ganglionated plexi (GP) ablation. The AF inducibility and duration induced by burst pacing were measured at each site before and after ipsolateral vagal stimulation or GP ablation.
Results: Before GP ablation, vagal stimulation markedly shortened the APD, decreased the slope of the restitution curves (Fig A⇓, LA for instance) and the 2:1 AP alternans cycle length (Fig B⇓), while increased the AF inducibility and duration once induced at each site. These effects were eliminated by GP ablation. Compared to baseline, GP ablation significantly increased the APD, steepened the restitution curves (>1) and facilitated the AP alternans while decreasing the AF inducibily and duration at most sites.
Conclusions: GP ablation steepens AP restitution curve and facilitates AP alternans while decreasing AF inducibility and duration. Vagal stimulation has the opposite effects. The change of AP restitution properties induced by autonomic interventions is not consistent with expectation in terms of AF inducibility and duration.