Comparison of cryothermia and radiofrequency current in safety and efficacy of catheter ablation within the canine coronary sinus close to the left circumflex coronary artery.
BACKGROUND
A canine model was used to compare cryoablation and radiofrequency ablation (RFA) within the coronary sinus (CS) in the ability to create a transmural CS myocardial (Trans-CSM) lesion and risk of coronary artery stenosis.


METHODS
After CS and left circumflex (LCx) coronary angiography, an intravascular ultrasound (IVUS) probe was placed in LCx in 29 dogs. An irrigated RFA catheter (8 dogs) or N(2)O cryoablation catheter (21 dogs) was inserted into the CS and positioned within 2 mm of LCx, confirmed by IVUS. RF (30-50W) was applied for 60 seconds at 10 CS sites. Cryoablation (-75 degrees C) was performed with one (n = 7) or two (n = 14) 4-minute applications. Dogs were sacrificed at 1 week (8 RFA and 13 cryoablation) or 3 months (8 cryoablation).


RESULTS
During RFA, IVUS showed wall thickening and LCx narrowing in 9 of 10 sites. Angiography at 5-minute post-RFA identified LCx narrowing (25-90%) at 6 of 10 sites and 25-75% narrowing at 4 of 9 sites at 1-week post-RFA. During cryoablation, IVUS showed reversible ice ball compression of LCx, and no LCx narrowing by angiography at 5 minutes, 1 week, or 3 months. Histology showed Trans-CSM lesion at 10 of 10 RFA sites and 20 of 21 cryoablation sites. RFA produced LCx medial necrosis at 7 of 10 sites, involving 20-50%(median 32.5%) of LCx circumference with loss of intima at 5 of 7 sites. Single and twice 4-minute cryoablation produced LCx medial necrosis at 2 of 7 and 8 of 14 sites (5-40%, median 25% circumference). Intima was preserved at 1 week (13/13) with minor proliferation (without narrowing) at 2 of 8 sites at 3 months.


CONCLUSIONS
Cryoablation in CS within 2 mm of LCx produces Trans-CSM lesions similar to RFA with lower risk of LCx stenosis than RFA.
Aoyama
Hiroshi
H
Cardiac Arrhythmia Research Institute and Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA. hiroshi-nakagawa@ouhsc.edu
Nakagawa
Hiroshi
H
Pitha
Jan V
JV
Khammar
George S
GS
Chandrasekaran
Krishnaswamy
K
Matsudaira
Kagari
K
Yagi
Tetsuo
T
Yokoyama
Katsuaki
K
Lazzara
Ralph
R
Jackman
Warren M
WM
D000818:Animals; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods*; D016009:Chi-Square Distribution; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000293:injuries / Q000601:surgery*; D003452:Cryosurgery / Q000009:adverse effects / Q000379:methods*; D004285:Dogs; D019160:Endosonography