title: Effects of perfusion on radiofrequency ablation in swine kidneys.
abstract: OBJECTIVE
  To evaluate the effect of vascular occlusion on the size of radiofrequency (RF) ablation lesions and to evaluate embolization as an occlusion method.
  
  
  METHODS
  The kidneys of six swine were surgically exposed. Fifteen RF ablation lesions were created in nine kidneys by using a 2-cm-tip single-needle ablation probe in varying conditions: Seven lesions were created with normal blood flow and eight were created with blood flow obstructed by means of vascular clamping (n = 5) or renal artery embolization (n = 3). The temperature, applied voltage, current, and impedance were recorded during RF ablation. Tissue-cooling curves acquired for 2 minutes immediately after the ablation were compared by using regression analysis. Lesions were bisected, and their maximum diameters were measured and compared by using analysis of variance.
  
  
  RESULTS
  The mean diameter of ablation lesions created when blood flow was obstructed was 60% greater than that of lesions created when blood flow was normal (1.38 cm +/- 0.05 [standard error of mean] vs 0.86 cm +/- 0.07, P <.001). The two methods of flow obstruction yielded lesions of similar mean sizes: 1.40 cm +/- 0.06 with vascular clamping and 1.33 cm +/- 0.07 with embolization. The temperature at the probe tip when lesions were ablated with normal blood flow decreased more rapidly than did the temperature when lesions were ablated after flow obstruction (P <.001), but no significant differences in tissue-cooling curves between the two flow obstruction methods were observed.
  
  
  CONCLUSIONS
  Obstruction of renal blood flow before and during RF ablation resulted in larger thermal lesions with potentially less variation in size compared with the lesions created with normal nonobstructed blood flow. Selective arterial embolization of the kidney vessels may be a useful adjunct to RF ablation of kidney tumors.
authors.affiliation: Center for Devices and Radiological Health, Office of Science and Technology, U.S. Food and Drug Administration, 12725 Twinbrook Pkwy, HFZ-133, Rockville, MD 20852, USA. iac@cdrh.fda.gov
authors.forename: Isaac
authors.initials: I
authors.lastname: Chang
authors.forename: Igor
authors.initials: I
authors.lastname: Mikityansky
authors.forename: Diane
authors.initials: D
authors.lastname: Wray-Cahen
authors.forename: William F
authors.initials: WF
authors.lastname: Pritchard
authors.forename: John W
authors.initials: JW
authors.lastname: Karanian
authors.forename: Bradford J
authors.initials: BJ
authors.lastname: Wood
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D007668:Kidney / Q000098:blood supply / Q000473:pathology* / Q000601:surgery*; D012079:Renal Circulation; D013552:Swine; D013696:Temperature