Abstract 12171: Biochemical and Histological Study of the Areas Exhibiting the Dominant Frequency and Those Exhibiting Continuous Fractionated Atrial Electrograms in Atrial Fibrillation Utilizing a Porcine Heart
(Background) Atrial areas exhibiting continuous fractionated atrial electrograms (CFE) have been considered to be effective target sites for catheter ablation (CA) to eliminatie atrial fibrillation (AF). Recently, areas with the dominant frequency (DF) have been regarded as a rotor of AF, and also have been regarded as new target sites for the successful catheter ablation of AF. However, a biochemical and histological assessment of the DF and CFE areas have systematically never been performed. The aim of this study was to investigate the biochemical and histological aspects with regard to the DF and CFE in terms of the efficacy of the CA of AF.
(Methods) The geometry of both the right and left atria was constructed using a three dimensional mapping system (NavX) in a total of 6 pigs. CFE and DF areas were visualized on the atrial geometry of NavX during electrically induced sustained AF by utilizing a multi-electrode circular catheter. Radiofrequency current energy (RF) was applied along the boundary of the DF and CFE areas for the macroscopic recognition of the DF and CFE areas in an excised heart. Tissue specimens of the DF, CFE and non-DF-CFE atrial areas were excised and examined for the histological analysis and quantitative RT-PCR for a biochemical analysis. Atrial fibrosis was evaluated by Hematoxyrin-Eosine (HE) and Mallory-Azan (MA) staining. Quantitative RT-PCR was performed to evaluate the expression of pro-collagen, MMP-2, alpha-SMA, Tyrosine hydroxylase (TH), and Choline acetyltransferase (ChAT).
(Results) The DF and CFE areas could easily be recognized by RF lesions created along their boundary. A mild deposition of a fibrotic area by HE and MA staining was observed in the atria. Deposition of collagen fibers evaluated by pro-collagen, MMP-2, and alpha-SMA also indicated no difference between the DF, CFE and non-DF-CFE areas. Expression of mRNA regarding TH and ChAT was lower in the DF and CFE areas than non-DF-CFE area.
(Conclusions) Areas exhibiting DF and CFE seem to have different characteristics than the non-DF-CFE sites in terms of autonomic innervation, not of tissue fibrosis.
- © 2012 by American Heart Association, Inc.