Nerve sprouting induced by radiofrequency catheter ablation in dogs.
OBJECTIVE
The purpose of this study was to test the hypothesis that radiofrequency (RF) catheter ablation results in cardiac nerve sprouting.


BACKGROUND
Nerve sprouting plays a role in cardiac arrhythmogenesis. Whether or not nerve sprouting occurs after RF catheter ablation is unclear.


METHODS
We performed RF catheter ablation in the right atrium (RA) and right ventricle (RV) in 10 dogs, which then were sacrificed in 2 hours (acute group, n = 5) or 1 month (chronic group, n = 5). Seven normal dogs were used as control. Immunohistochemical staining for growth-associated protein 43 (GAP-43) was performed to measure growing (sprouting) nerves.


RESULTS
A significant increase of GAP-43 immunoreactive nerve fiber density was observed at the RA ablation sites in 2 hours (4,410 +/- 1,379 microm(2)/mm(2)) and in 1 month (2,948 +/- 666 microm(2)/mm(2)) after ablation compared to controls (1,377 +/- 471 microm(2)/mm(2), P = .0001). At remote sites (>2 cm away from ablation sites) of RA, RF ablation also resulted in robust nerve sprouting in both the acute group (5,846 +/- 3241 microm(2)/mm(2)) and the chronic group (6,030 +/- 2226 microm(2)/mm(2)). RF ablation in the RV did not increase nerve density at the ablation sites, but nerve density was increased at remote sites in 2 hours (1,345 +/- 451 microm(2)/mm(2), P = .0136) that was reduced down to the normal control level (722 +/- 337 microm(2)/mm(2)) in 1 month.


CONCLUSIONS
Nerve sprouting occurred within 2 hours after RF ablation in both the RA and RV and persisted for at least 1 month in the RA but not the RV. The increased GAP-43(+) nerve densities developed at both the ablation and the remote sites.
Okuyama
Yuji
Y
Division of Cardiology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Pak
Hui-Nam
HN
Miyauchi
Yasushi
Y
Liu
Yen-Bin
YB
Chou
Chung-Chuan
CC
Hayashi
Hideki
H
Fu
Katherine J
KJ
Kerwin
Walter F
WF
Kar
Saibal
S
Hata
Cary
C
Karagueuzian
Hrayr S
HS
Fishbein
Michael C
MC
Chen
Peng-Sheng
PS
Chen
Lan S
LS
D000818:Animals; D017115:Catheter Ablation; D004285:Dogs; D019922:GAP-43 Protein / Q000378:metabolism*; D006321:Heart / Q000294:innervation*; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D009412:Nerve Fibers / Q000378:metabolism; D009416:Nerve Regeneration / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*
D019922:GAP-43 Protein