Circulation, Vol 89, 2390-2395, Copyright © 1994 by American Heart Association
JG Whayne, S Nath and DE Haines
BACKGROUND: Radiofrequency (RF) catheter ablation lesion size has been
limited by the small volume of tissue directly heated by the RF electrode.
Microwave (MW) energy has been proposed as an alternative energy source to
generate larger lesions because of its increased volume of direct tissue
heating. To further characterize MW ablation of myocardium, we studied the
temperature-versus-distance profiles during MW ablation in an in vitro
model of perfused and superfused porcine right ventricular free wall.
METHODS AND RESULTS: Radial tissue temperatures in 19 isolated porcine
right ventricles were measured and recorded with four fluoroptic
thermometry probes placed within the myocardium at 2.5-mm radial increments
from the catheter. The MW antenna catheters used were monopolar and
helical-coil antennas resonating at 915 and 2450 MHz. Durations of energy
delivery for a 915- MHz MW monopolar antenna (60 to 600 seconds) and a
4-mm-tip RF electrode (60 and 300 seconds) were varied to compare time
courses of lesion formation. For each lesion, the temperature at the lesion
border zone (the isotherm of irreversible tissue injury) was determined.
Similar lesion size and temperature profiles were observed for 915- versus
2450-MHz MW antennas and monopolar versus helical-coil MW antennas. Lesion
depth for the 915-MHz monopolar antenna increased monoexponentially with a
half-time of 170 seconds. The isotherms for all MW antenna designs were not
significantly different. The mean isotherm of irreversible tissue injury
for MW lesions was not significantly different from the mean isotherm for
RF lesions (54.4 degrees C versus 53.6 degrees C, respectively).
CONCLUSIONS: Microwave ablation has the potential to directly heat a
greater volume of tissue than RF ablation but only with efficient MW
antennas. The primary mechanism of tissue injury for both MW and RF
ablation appears to be thermal.
ARTICLES
Microwave catheter ablation of myocardium in vitro. Assessment of the characteristics of tissue heating and injury
Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908.
This article has been cited by other articles:
 |
|
 |
|
  S. L. Gaynor, G. D. Byrd, M. D. Diodato, Y. Ishii, A. M. Lee, S. M. Prasad, J. Gopal, R. B. Schuessler, and R. J. Damiano Jr Microwave Ablation for Atrial Fibrillation: Dose-Response Curves in the Cardioplegia-Arrested and Beating Heart Ann. Thorac. Surg., January 1, 2006; 81(1): 72 - 76. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. Wisser, C. Khazen, E. Deviatko, G. Stix, T. Binder, R. Seitelberger, H. Schmidinger, and E. Wolner Microwave and radiofrequency ablation yield similar success rates for treatment of chronic atrial fibrillation Eur. J. Cardiothorac. Surg., June 1, 2004; 25(6): 1011 - 1017. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. Chiappini, R. Di Bartolomeo, and G. Marinelli The surgical treatment of atrial fibrillation with microwave ablation: preliminary experience and results Interactive CardioVascular and Thoracic Surgery, September 1, 2003; 2(3): 327 - 330. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Watanabe, J.-i. Hayashi, M. Sugawara, M. Hiratsuka, and S. Eguchi Experimental application of microwave tissue coagulation to ventricular myocardium Ann. Thorac. Surg., March 1, 1999; 67(3): 666 - 671. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. H. Petersen, X. Chen, A. Pietersen, J. H. Svendsen, and S. Haunso Lesion Dimensions During Temperature-Controlled Radiofrequency Catheter Ablation of Left Ventricular Porcine Myocardium : Impact of Ablation Site, Electrode Size, and Convective Cooling Circulation, January 19, 1999; 99(2): 319 - 325. [Abstract] [Full Text] [PDF]
|
|