title: Percutaneous microwave ablation with a long side-firing antenna array can successfully treat a nonsurgical chronic ovine atrial flutter model.
abstract: BACKGROUND
  Long side-firing microwave (MW) arrays can deliver energy uniformly over its length without the need for intimate endocardial contact. We hypothesize that a novel 6 Fr 20 mm long percutaneous high-efficiency MW antenna array ablation catheter can rapidly create long, continuous, and transmural linear ablation lesions.
  
  
  RESULTS
  Cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) was created in 11 sheep by a line of radiofrequency ablation lesions in the posterior right atrium (RA) linking the venae cavae. After 4-6 weeks recovery, CTI-dependent AFL was still inducible in all 11 sheep (cycle length 178 +/- 13 ms). MW ablation of the CTI at 100 W for 30 seconds was then performed with an endpoint of AFL noninducibility. AFL was not inducible in all 11 sheep after 4.3 +/- 3.3 MW applications (129 +/- 99 seconds). The last 6 animals needed fewer ablations (2.2 +/- 1.5) and 3 of these sheep required only a single ablation. Although conduction times from proximal coronary sinus to lateral RA and vice versa increased postablation (51 +/- 14 ms to 118 +/- 31 ms [P = 0.0002] and 60 +/- 13 ms to 119 +/- 28 ms [P = 0.0001], respectively), AFL was still inducible in 2 sheep and further ablation was needed to reach the endpoint.
  
  
  CONCLUSIONS
  High-efficiency side-firing MW array ablation can rapidly create long linear and electrically intact lesions in an ovine AFL model. AFL noninducibility may be a more reliable indicator than CTI conduction times of an intact line of ablation in this animal model.
authors: University of Sydney, Sydney, Australia.
authors: Toon Wei
authors: TW
authors: Lim
authors: Ray
authors: R
authors: Clout
authors: Michael A
authors: MA
authors: Barry
authors: Juntang
authors: J
authors: Lu
authors: Kaimin
authors: K
authors: Huang
authors: Stuart P
authors: SP
authors: Thomas
mesh_terms: D000818:Animals; D001282:Atrial Flutter / Q000175:diagnosis / Q000601:surgery*; D002908:Chronic Disease; D004598:Electrosurgery / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D008872:Microwaves / Q000627:therapeutic use*; D012756:Sheep; D014159:Transducers; D016896:Treatment Outcome