title: Prospective Evaluation of Electromyography-Guided Phrenic Nerve Monitoring During Superior Vena Cava Isolation to Anticipate Phrenic Nerve Injury.
abstract: BACKGROUND
  Right phrenic nerve injury (PNI) is a major concern during superior vena cava (SVC) isolation due to the anatomical close proximity. The functional and histological severity of PNI parallels the degree of the reduction in the compound motor action potential (CMAP) amplitude. This study aimed to evaluate the feasibility of monitoring CMAPs during SVC isolation to anticipate PNI during atrial fibrillation (AF) ablation.
  
  
  METHODS
  Thirty-nine paroxysmal AF patients were prospectively enrolled. Radiofrequency energy was delivered point-by-point for 30 seconds with 20 W until eliminating all SVC potentials after the pulmonary vein isolation. Right diaphragmatic CMAPs were obtained from modified surface electrodes by pacing from the right subclavian vein. Radiofrequency applications were applied without fluoroscopy under CMAP monitoring at sites with phrenic nerve capture by high output pacing.
  
  
  RESULTS
  Electrical SVC isolation was successfully achieved with a mean of 9.4 ± 3.3 applications in all patients. In 3 (7.5%) patients, the SVC was isolated without radiofrequency delivery at phrenic nerve capture sites. Among a total of 346 applications in the remaining 36 patients, 71 (20.5%) were delivered while monitoring CMAPs. In 1 (1.4%) application, the RF application was interrupted due to a decrease in the CMAP amplitude. However, no PNI was detected on fluoroscopy, and the decreased amplitude recovered spontaneously. The remaining 70 (98.6%) applications exhibited no significant changes in the CMAP amplitude throughout the applications (from 1.01 ± 0.47 to 0.98 ± 0.45 mV, P = 0.383).
  
  
  CONCLUSIONS
  Stable right diaphragmatic CMAPs could be obtained, and monitoring CMAPs might be useful for anticipating right PNI during SVC isolation.
authors.affiliation: Cardiovascular Center, Tsuchiura Kyodo Hospital, Tsuchiura, Ibaraki, Japan.|Heart Rhythm Center, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Miyazaki
authors.affiliation: Cardiovascular Center, Tsuchiura Kyodo Hospital, Tsuchiura, Ibaraki, Japan.
authors.forename: Noboru
authors.initials: N
authors.lastname: Ichihara
authors.affiliation: Cardiovascular Center, Tsuchiura Kyodo Hospital, Tsuchiura, Ibaraki, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Cardiovascular Center, Tsuchiura Kyodo Hospital, Tsuchiura, Ibaraki, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Taniguchi
authors.affiliation: Cardiovascular Center, Tsuchiura Kyodo Hospital, Tsuchiura, Ibaraki, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Hachiya
authors.affiliation: Cardiovascular Center, Tsuchiura Kyodo Hospital, Tsuchiura, Ibaraki, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Araki
authors.affiliation: Cardiovascular Center, Tsuchiura Kyodo Hospital, Tsuchiura, Ibaraki, Japan.
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Takagi
authors.affiliation: Cardiovascular Center, Tsuchiura Kyodo Hospital, Tsuchiura, Ibaraki, Japan.
authors.forename: Jin
authors.initials: J
authors.lastname: Iwasawa
authors.affiliation: Cardiovascular Center, Tsuchiura Kyodo Hospital, Tsuchiura, Ibaraki, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Kuroi
authors.affiliation: Heart Rhythm Center, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Kenzo
authors.initials: K
authors.lastname: Hirao
authors.affiliation: Cardiovascular Center, Tsuchiura Kyodo Hospital, Tsuchiura, Ibaraki, Japan.
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Iesaka
mesh_terms: D001281:Atrial Fibrillation / Q000175:diagnosis / Q000601:surgery*; D017115:Catheter Ablation / Q000009:adverse effects*; D004576:Electromyography; D005240:Feasibility Studies; D005260:Female; D006329:Heart Conduction System / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D059348:Peripheral Nerve Injuries / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D010791:Phrenic Nerve / Q000293:injuries*; D011379:Prognosis; D011446:Prospective Studies; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014683:Vena Cava, Superior / Q000601:surgery*
keywords: atrial fibrillation; catheter ablation; compound motor action potential; phrenic nerve injury; superior vena cava