Effect of cryoballoon inflation at the right superior pulmonary vein orifice on phrenic nerve location.
BACKGROUND
Cryoballoon catheter ablation was developed to simplify ablation for atrial fibrillation (AF). Initial enthusiasm for its widespread use has been dampened by phrenic nerve (PN) injury (PNI).


OBJECTIVE
The purpose of this study was to assess the effect of cryoballoon inflation at the right superior pulmonary vein (RSPV) orifice on PN location and to elucidate the potential mechanism of PNI.


METHODS
Twenty patients with paroxysmal atrial fibrillation underwent ablation performed with a second-generation 28-mm cryoballoon catheter. Before ablation, the pacing-determined PN course was delineated along the right atrium. PN location and its relation to the RSPV as well as RSPV surface distortions after balloon inflation were established with a NavX mapping system.


RESULTS
During RSPV ablation, the inflated balloon surface extended anteriorly 6.3 ± 1.8 mm outside the RSPV. This narrowed the distance between the PN capture points in the RSPV vs PN location from 11.4 ± 5.0 mm to 7.5 ± 5.0 mm (P = .0002) and increased the PN capture area from 1.9 ± 1.3 cm(2) to 3.2 ± 1.8 cm(2) (P = .0004). Furthermore, the PN capture points shifted toward the orifice within the RSPV and after balloon inflation were located significantly closer to the orifice in the 3 patients with transient PNI than in those without PNI.


CONCLUSIONS
Cryoballoon inflation at the RSPV orifice alters PV/left atrial surface geometry, reducing the distance between the energy delivery source and the PN and increasing PN area, possibly explaining the mechanism of PNI. PN pacing within the RSPV after balloon inflation may be useful for preventing PNI.
Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
Kazuki
K
Iso
Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan. Electronic address: cocakochan@gmail.com.
Koichi
K
Nagashima
Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
Yasuo
Y
Okumura
Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
Ichiro
I
Watanabe
Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
Toshiko
T
Nakai
Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
Kimie
K
Ohkubo
Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
Kazumasa
K
Sonoda
Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
Rikitake
R
Kogawa
Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
Naoko
N
Sasaki
Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
Keiko
K
Takahashi
Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
Sayaka
S
Kurokawa
Nihon Kohden Co., Ltd., Tokyo, Japan.
Mizuki
M
Nikaido
Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
Atsushi
A
Hirayama
D000368:Aged; D001281:Atrial Fibrillation / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D003452:Cryosurgery / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D059348:Peripheral Nerve Injuries / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control; D010791:Phrenic Nerve / Q000293:injuries; D011667:Pulmonary Veins / Q000601:surgery*; D016896:Treatment Outcome
Atrial fibrillation; Phrenic nerve injury; Pulmonary vein isolation; Second-generation cryoballoon