title: Enhanced Radiofrequency Ablation With Magnetically Directed Metallic Nanoparticles.
abstract: BACKGROUND
  Remote heating of metal located near a radiofrequency ablation source has been previously demonstrated. Therefore, ablation of cardiac tissue treated with metallic nanoparticles may improve local radiofrequency heating and lead to larger ablation lesions. We sought to evaluate the effect of magnetic nanoparticles on tissue sensitivity to radiofrequency energy.
  
  
  RESULTS
  Ablation was performed using an ablation catheter positioned with 10 g of force over prepared ex vivo specimens. Tissue temperatures were measured and lesion volumes were acquired. An in vivo porcine thigh model was used to study systemically delivered magnetically guided iron oxide (FeO) nanoparticles during radiofrequency application. Magnetic resonance imaging and histological staining of ablated tissue were subsequently performed as a part of ablation lesion analysis. Ablation of ex vivo myocardial tissue treated with metallic nanoparticles resulted in significantly larger lesions with greater impedance changes and evidence of increased thermal conductivity within the tissue. Magnet-guided localization of FeO nanoparticles within porcine thigh preps was demonstrated by magnetic resonance imaging and iron staining. Irrigated ablation in the regions with greater FeO, after FeO infusion and magnetic guidance, created larger lesions without a greater incidence of steam pops.
  
  
  CONCLUSIONS
  Metal nanoparticle infiltration resulted in significantly larger ablation lesions with altered electric and thermal conductivity. In vivo magnetic guidance of FeO nanoparticles allowed for facilitated radiofrequency ablation without direct infiltration into the targeted tissue. Further research is needed to assess the clinical applicability of this ablation strategy using metallic nanoparticles for the treatment of cardiac arrhythmias.
authors.affiliation: From the Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of Colorado, Aurora.
authors.forename: Duy T
authors.initials: DT
authors.lastname: Nguyen
authors.affiliation: From the Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of Colorado, Aurora.
authors.forename: Wendy S
authors.initials: WS
authors.lastname: Tzou
authors.affiliation: From the Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of Colorado, Aurora.
authors.forename: Lijun
authors.initials: L
authors.lastname: Zheng
authors.affiliation: From the Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of Colorado, Aurora.
authors.forename: Waseem
authors.initials: W
authors.lastname: Barham
authors.affiliation: From the Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of Colorado, Aurora.
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Schuller
authors.affiliation: From the Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of Colorado, Aurora.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Shillinglaw
authors.affiliation: From the Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of Colorado, Aurora.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Quaife
authors.affiliation: From the Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of Colorado, Aurora. william.sauer@ucdenver.edu.
authors.forename: William H
authors.initials: WH
authors.lastname: Sauer
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D017115:Catheter Ablation / Q000379:methods*; D002417:Cattle; D004195:Disease Models, Animal; D005290:Ferric Compounds / Q000008:administration & dosage*; D008081:Liposomes; D019028:Magnetic Resonance Imaging, Cine; D059346:Magnets; D053768:Metal Nanoparticles / Q000008:administration & dosage*; D009206:Myocardium / Q000473:pathology*; D013552:Swine
chemical_list: D005290:Ferric Compounds; D008081:Liposomes; C000499:ferric oxide
keywords: cardiac arrhythmias; iron; magnet; magnetic resonance imaging; nanoparticle