title: Nonthermal cardiac catheter ablation using photodynamic therapy.
abstract: BACKGROUND
  Radiofrequency ablation has limitations, largely related to creation of lesions by heating. Here, we report the first nonthermal ablation by applying photodynamic therapy (PDT) to cardiac tissues using a custom-made deflectable laser catheter. The present study investigated the feasibility of PDT for cavotricuspid isthmus ablation in a canine model.
  
  
  RESULTS
  We evaluated the pharmacokinetic profiles of 17 canines after administration of a photosensitizer (talaporfin sodium) by various protocols. We succeeded in maintaining the photosensitizer concentration at a level in excess of the clinically effective dose for humans. Using a 4-polar 7-French deflectable laser catheter, we performed PDT-mediated cavotricuspid isthmus ablation in 8 canines. PDT caused oxidative injury only to the irradiated area and successfully produced a persistent electric conduction block. No acute, gross changes such as edematous degeneration, thrombus formation, steam pops, or traumatic injury were observed after irradiation. Hematoxylin and eosin staining of tissues samples also showed well-preserved endothelial layers. Testing of the blood samples taken before and after the procedure revealed no remarkable changes. Lesion size at 2 weeks after the procedure and the temperature data collected during irradiation were compared between the PDT and irrigated radiofrequency ablation procedures. A ventricular cross-section revealed a solid PDT lesion, which was as deep as a radiofrequency lesion. In addition, endocardial, surficial, and intramural temperature monitoring during the PDT irradiation clearly demonstrated the nonthermal nature of the ablation technique.
  
  
  CONCLUSIONS
  Nonthermal PDT-mediated catheter ablation is a potentially novel treatment for cardiac arrhythmias.
authors.affiliation: Department of Cardiology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Kimura
authors.forename: Seiji
authors.initials: S
authors.lastname: Takatsuki
authors.forename: Shunichiro
authors.initials: S
authors.lastname: Miyoshi
authors.forename: Kotaro
authors.initials: K
authors.lastname: Fukumoto
authors.forename: Mei
authors.initials: M
authors.lastname: Takahashi
authors.forename: Emiyu
authors.initials: E
authors.lastname: Ogawa
authors.forename: Arisa
authors.initials: A
authors.lastname: Ito
authors.forename: Tsunenori
authors.initials: T
authors.lastname: Arai
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ogawa
authors.forename: Keiichi
authors.initials: K
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D001282:Atrial Flutter / Q000188:drug therapy* / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D004195:Disease Models, Animal; D004285:Dogs; D005240:Feasibility Studies; D005471:Fluoroscopy; D053685:Laser Therapy / Q000379:methods*; D010778:Photochemotherapy / Q000379:methods*; D011166:Porphyrins / Q000494:pharmacology
chemical_list: D011166:Porphyrins; C053434:Talaporfin
keywords: atrial flutter; catheter ablation; photochemotherapy; talaporfin