title: Effect of frequency on entrance and propagation pattern of high-frequency (radiofrequency) electrical currents in biologic tissues.
abstract: BACKGROUND
  Radiofrequency electrical currents have a tendency to move toward the center of the bulk of biologic tissues.
  
  
  OBJECTIVE
  To evaluate the effect of the frequency of currents on their entrance and propagation pattern in biologic tissues.
  
  
  METHODS
  Three electrosurgical generators with 0.4, 1.5, and 3 MHz frequency outputs were studied. Current was applied using a metallic needle introduced into a piece of cow liver, with different amounts of energy delivered at multiple points. Cross-sections of the liver were then studied for tissue effect. The diameters of the coagulated areas at the deepest and most superficial parts were measured. The tendency of the currents for penetration in the deeper layers of tissue rather than in the superficial layers was assessed using the superficial diameter/deep diameter ratio.
  
  
  RESULTS
  Diameter of coagulated area was larger around deeper parts than around superficial parts of the electrode. No correlation between frequency of current and the superficial/deep diameter ratio of the coagulation zone was found.
  
  
  CONCLUSIONS
  Radiofrequency currents have a tendency to move toward the center of the tissue. Frequency of current over the range of 0.4-3 MHz did not show any effect on this tendency.
authors.affiliation: Center for Dermatology Research, Department of Dermatology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: A
authors.initials: A
authors.lastname: Taheri
authors.affiliation: Department of Pathology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: P
authors.initials: P
authors.lastname: Mansoori
authors.affiliation: Center for Dermatology Research, Department of Dermatology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Huang
authors.affiliation: Center for Dermatology Research, Department of Dermatology, Wake Forest School of Medicine, Winston-Salem, NC, USA.|Department of Pathology, Wake Forest School of Medicine, Winston-Salem, NC, USA.|Department of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Feldman
mesh_terms: D065638:Absorption, Radiation; D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D002417:Cattle; D004553:Electric Conductivity; D006498:Hepatectomy / Q000379:methods*; D066298:In Vitro Techniques; D008099:Liver / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery*; D011829:Radiation Dosage; D011846:Radio Waves
keywords: current; electrical; frequency; high-frequency; propagation; radiofrequency; skin; tissue