Abstract:

Objective   To quantificationally investigate the autonomic neural remodeling of pulmonary vein-left atrium (PV-LA) junction in a prolonged right atrial pacing canine model. Methods   A total of 12 healthy adult mongrel dogs, weighing 15-20kg, were randomly divided into 2 groups: 6 (paced group) underwent rapid right atrial pacing at 400 bpm for 4 weeks; 6 (control group) were not paced. The effective refractory period (ERP) of left superior pulmonary vein-left atrium (LSPV-LA) junction in all animals was measured and the experimental tissues were harvested from 1cm around all PV-LA junctions immediately after 4 weeks of pacing. Expressions of tyrosine hydroxylase (TH) and choline acetyltransterase (ChAT) were detected with immunohistochemical staining and Western blotting. Results   Compared with that of the control group, the ERP of LSPV-LA junction of the paced group was significantly shortened ［(83.33±16.33) vs (111.67±20.41) ms, P<0.05］. Spontaneous atrial fibrillation developed in 2 animals in the paced group, but not in the control group. Immunohistochemistry showed that the average density and heterogeneity of TH and ChAT at LSPV-LA junction in the paced group were significantly higher than those of the control group (P<0.01). Western blotting showed that the expressions of TH and ChAT at the 4 PV-LA junctions in the paced group increased markedly compared with those of the control group (P<0.01). Conclusion    Autonomic neural remodeling does exist in the PV-LA junction after prolonged atrial pacing, which may contribute to the initiation of atrial fibrillation. This may promote the management of atrial fibrillation by effectively guiding the radiofrequency catheter ablation procedure.

Key words: Autonomic neural remodeling; Pulmonary vein-left atrium junction; Atrial fibrillation; Radiofrequency catheter ablation