Irrigation-Tipped vs. Conventional-Tipped Catheters for Ablation of Atrial Flutter
April 1, 2000 3 minutes read
Irrigation-Tipped vs. Conventional-Tipped Catheters for Ablation of Atrial Flutter
abstract & commentary
Synopsis: Use of irrigation-tipped catheters improves the safety, efficiency, and duration procedures for radiofrequency ablation of atrial flutter.
Source: Jais P, et al. Circulation 2000;101:772-776.
In this paper, jais and colleagues from bordeaux, France, report a randomized trial comparing an irrigation-tipped catheter to a conventional catheter for the ablation of atrial flutter. Irrigation ablation catheters cool the electrode at the tip of the catheter by irrigating saline through the catheter. This prevents heat build-up, with subsequent boiling at the catheter tip, and permits greater heating of the tissue during radiofrequency energy delivery. Jais et al compared an irrigation-tipped catheter that had either a 3.5-mm or a 5-mm tip to a conventional 4-mm electrode-tip ablation catheter. The study group included 50 patients who were referred for initial ablation of atrial flutter. Typical atrial flutter was confirmed by right atrial mapping showing counterclockwise activation around the tricuspid annulus. The technique involved sequential point lesions from the tricuspid annulus to the inferior vena cava. Each catheter was used to create a line of lesions through the isthmus between the tricuspid annulus and inferior vena cava with termination of atrial flutter and production of bidirectional isthmus block, the end point of the ablation procedure. As part of this protocol, coronary angiography was performed to look for asymptomatic coronary damage related to the ablation procedure.
All 24 patients treated with the irrigation-tipped catheter had successful ablation of the atrial flutter in contrast to 22 of 26 patients who were treated with the conventional catheter. Four of the conventional catheter patients were crossed over to the irrigation-tipped catheter and had successful completion of their ablation using the latter approach. There was a significantly shorter procedure duration (53 ± 41 vs 27 ± 16 minutes) and x-ray exposure time (18 ± 14 vs 9 ± 6 minutes) with the irrigation-tipped catheter.
No significant side effects related to the radiofrequency ablation occurred. There were no changes in the coronary angiograms performed after the ablation procedure. Thirteen ± 10 applications required isthmus block in the conventional catheter group vs. five ± three applications in the irrigation-tipped catheter group. Jais et al conclude that use of irrigation-tipped catheters improves the safety, efficiency, and duration procedures for radiofrequency ablation of atrial flutter.
Comment by John P. DiMarco, MD, PhD
Build-up of temperature at the ablation tip with subsequent boiling and impedence rises has limited the use of conventional catheters for radiofrequency ablation. Cooling the catheter tip has been one solution to this problem and it has been shown that cooled-tip catheters can produce larger lesions with a decreased risk of these problems. In this paper, Jais et al show that cooled-tip catheters are highly effective in radiofrequency ablation of common atrial flutter.
However, the results here may be an overstatement of the benefit with the cooled-tip catheters. Many laboratories use 5-mm or 8-mm tipped catheters instead of the smaller 4-mm size used here for comparison for flutter ablation. These larger tipped catheters dissipate heat better and yet remain effective for flutter ablations. In our laboratory, we also do not use sequential point lesions to produce the ablation line. Rather, we gradually withdraw the catheter during continuous RF delivery from the tricuspid annulus to the inferior vena cava. This technique often requires application of fewer lesions and in our hands has shortened procedure duration. Whether using a slightly bigger catheter tip and a pullback lesion with the cooled-tip catheter might further shorten procedure duration is not known.
New developments in catheter design will probably permit placement of linear lesions with a single catheter that is not moved at all during the procedure. New catheter designs are now undergoing testing for flutter ablation. These catheters will allow either sequential or continuous application of radiofrequency along a much longer segment of catheter. At this point, the chilled-tip catheter appears to offer some advantages over conventional catheters. Questions of cost and laboratory experience should probably be used to determine whether their use will be the initial approach.
Saline-cooled ablation catheters vs. conventional catheters produce:
a. less tissue damage during RF energy delivery.
b. more tissue damage during RF energy delivery.
c. higher ablation success rates.
d. b and c
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