title: Fatal end of a safety algorithm for pulmonary vein isolation with use of high-intensity focused ultrasound.
abstract: BACKGROUND
  High-intensity focused ultrasound (HIFU) can achieve pulmonary vein isolation (PVI), but there are safety concerns after severe complications. Therefore, we evaluated an esophageal temperature (ET)-guided safety algorithm to apply HIFU safely.
  
  
  RESULTS
  After standard left atrial access, HIFU was repeatedly applied until PVI was complete. A safety algorithm was used: <or=3 complete ablations per pulmonary vein (PV), early abortion when no effect after 50%of programmed time or when ET was >or=40.0 degrees C, use of power modulation (PM) at ET 39.0 degrees C: to reduce ablation temperature in surrounding tissue, acoustic power is switched on/off at 1 Hz; in all first ablations, use of PM after 50% of programmed time. Touch-up radiofrequency ablation was used when PVI failed. Periprocedural ET monitoring and endoscopy 2 days after ablation were performed. Twenty-eight patients (18 males; mean age at enrollment, 63 years), with paroxysmal atrial fibrillation (AF; n=19) and persistent AF (n=9) were included. In 84 of 109 PV (9 of 25 patients), PVI was achieved using HIFU only. In 9 of 109 PV, HIFU was aborted because of high ET. Mean ET at the end of the ablations with and without use of PM were 38.1+/-2.0 degrees C and 37.4+/-1.0 degrees C (P=0.0002). During endoscopy in 2 of 26 patients, a small thermal lesion was found. Other complications included 2 persistent phrenic nerve palsies, 1 ischemic stroke, 1 pericardial effusion 48 days after ablation, 1 unexplained death 49 days after ablation, and 1 lethal atrial-to-esophageal fistula 31 days after ablation.
  
  
  CONCLUSIONS
  The safety algorithm failed to prevent lethal complications. Currently HIFU does not meet the safety standards required for treatment of atrial fibrillation.
authors.affiliation: Asklepios Klinik St Georg, Department of Cardiology, Hamburg, Germany.
authors.forename: Kars
authors.initials: K
authors.lastname: Neven
authors.forename: Boris
authors.initials: B
authors.lastname: Schmidt
authors.forename: Andreas
authors.initials: A
authors.lastname: Metzner
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Otomo
authors.forename: Dieter
authors.initials: D
authors.lastname: Nuyens
authors.forename: Tom
authors.initials: T
authors.lastname: De Potter
authors.forename: K R Julian
authors.initials: KR
authors.lastname: Chun
authors.forename: Feifan
authors.initials: F
authors.lastname: Ouyang
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Kuck
mesh_terms: D000368:Aged; D000465:Algorithms; D001281:Atrial Fibrillation / Q000401:mortality / Q000503:physiopathology / Q000601:surgery*; D001833:Body Temperature Regulation; D002545:Brain Ischemia / Q000209:etiology; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D004937:Esophageal Fistula / Q000209:etiology / Q000401:mortality; D004945:Esophagoscopy; D004947:Esophagus / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D010243:Paralysis / Q000209:etiology; D010490:Pericardial Effusion / Q000209:etiology; D010791:Phrenic Nerve / Q000293:injuries; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011667:Pulmonary Veins / Q000503:physiopathology / Q000601:surgery*; D018570:Risk Assessment; D020521:Stroke / Q000209:etiology; D016896:Treatment Outcome; D014464:Ultrasonic Therapy / Q000009:adverse effects / Q000401:mortality