title: Carbon nanotube facilitation of myocardial ablation with radiofrequency energy.
abstract: BACKGROUND
  The use of carbon nanotubes (CNTs) in oncology has been proposed for the purpose of sensitizing tumors to radiofrequency (RF) ablation. We hypothesize that myocardial tissue infiltrated with CNTs will improve thermal conductivity of RF heating and lead to altered ablation lesion characteristics.
  
  
  METHODS
  An ex vivo model consisting of viable bovine myocardium, a circulating saline bath at 37 °C, a submersible load cell, and a deflectable sheath was assembled. A 4-mm nonirrigated ablation catheter was positioned with 10 gm of force over bovine myocardium infiltrated with CNTs, 0.9% saline, or sham injections. A series of ablation lesions were delivered at 20 and 50 W, and lesion volumes were acquired by analyzing tissue sections with a digital micrometer. Tissue temperature analyses at 3 and 5 mm depths were also performed.
  
  
  RESULTS
  Myocardial tissue treated with CNTs resulted in significantly larger lesions at both low and high power settings. The electrical impedance was increased in CNT treated tissue with a greater impedance change observed in the CNT infiltrated myocardium. The thermal conductivity of heat generated by application of RF in the tissue was altered by the presence of CNTs, resulting in higher temperatures at 3 and 5 mm depths for both 20 and 50 W.
  
  
  CONCLUSIONS
  Myocardial tissue treated with CNTs resulted in significantly larger lesions at both low and high power settings. The electrical and thermal conductivity of heat generated by application of RF in myocardial tissue was altered by the presence of CNTs. Further research is needed to assess the in vivo applicability for this concept of facilitated ablation with CNTs.
authors.affiliation: Section of Cardiac Electrophysiology, University of Colorado, Aurora, Colorado.
authors.forename: Duy T
authors.initials: DT
authors.lastname: Nguyen
authors.forename: Waseem
authors.initials: W
authors.lastname: Barham
authors.forename: Lijun
authors.initials: L
authors.lastname: Zheng
authors.forename: Benjamin
authors.initials: B
authors.lastname: Shillinglaw
authors.forename: Wendy S
authors.initials: WS
authors.lastname: Tzou
authors.forename: Bonnie
authors.initials: B
authors.lastname: Neltner
authors.forename: Luisa
authors.initials: L
authors.lastname: Mestroni
authors.forename: Susanna
authors.initials: S
authors.lastname: Bosi
authors.forename: Laura
authors.initials: L
authors.lastname: Ballerini
authors.forename: Maurizio
authors.initials: M
authors.lastname: Prato
authors.forename: William H
authors.initials: WH
authors.lastname: Sauer
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000187:drug effects / Q000502:physiology; D006348:Cardiac Surgical Procedures / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods*; D002417:Cattle; D003131:Combined Modality Therapy; D006321:Heart / Q000187:drug effects* / Q000502:physiology*; D066298:In Vitro Techniques; D009206:Myocardium / Q000473:pathology; D053758:Nanoparticles / Q000627:therapeutic use*; D037742:Nanotubes, Carbon; D016896:Treatment Outcome
chemical_list: D037742:Nanotubes, Carbon
keywords: carbon nanotubes; catheter ablation; lesion size; myocardium; thermal conductivity