title: Early assessment of biophysical parameters predicts lesion formation during RF energy delivery in vitro.
abstract: BACKGROUND
  There is no currently available technology to accurately predict ablation lesion size within seconds of onset of delivery of radiofrequency (RF) energy.
  
  
  METHODS
  Changes in several biophysical characteristics of cardiac tissue in vitro within 5-15 seconds of the onset of RF energy were evaluated to predict lesion formation at 120 seconds. RF energy was applied with a 50% duty cycle to measure heating and cooling behavior of the electrode temperature sensor. Changes in impedance, phase angle, and the resulting resistance and capacitance, power, and electrode temperature variation during RF ablation were analyzed.
  
  
  RESULTS
  A combination of electrical-based parameters measured online as early as 5, 10, and 15 seconds after onset of RF energy in vitro was found to explain 63, 75, and 76% of variability (R(2) ) of lesion volume. These correlations were better than any single parameter, particularly impedance and target temperature.
  
  
  CONCLUSIONS
  A combination of electrical-based parameters provides better correlation with lesion formation than a single parameter and may be useful to predict lesion size during RF ablation in vivo. These parameters appear to represent changes in the tissue during heating.
authors.affiliation: University of Arizona, Arizona Cancer Center Bard Electrophysiology Division, Lowell, MA, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Bosnos
authors.forename: José M
authors.initials: JM
authors.lastname: Guillén-Rodríguez
authors.forename: Ding S
authors.initials: DS
authors.lastname: He
authors.forename: Frank I
authors.initials: FI
authors.lastname: Marcus
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000503:physiopathology* / Q000601:surgery*; D017115:Catheter Ablation; D002417:Cattle; D017097:Electric Impedance; D004566:Electrodes; D004735:Energy Transfer; D006358:Hot Temperature