High resistance of atrioventricular node to cryoablation: a great safety margin targeting perinodal arrhythmic
Nicasio Pérez-Castellano1, Julián Villacastín, Javier Moreno
1Unit of Arrhythmias, Cardiovascular Institute, San Carlos University Hospital, Madrid, Spain. nperez.hcsc@salud.madrid.org
Background:
Findings from animal studies and small series of patients support the greater safety of cryoenergy over radiofrequency in the ablation of arrhythmic substrates near the AV node.
Objectives:
The purpose of this study was to systematically evaluate the electrophysiologic effects of successive cryoenergy applications to the human AV node in order to better define the safety margin of cryothermal ablation.
Methods:
In 15 patients referred for AV nodal ablation, 94 cryomapping and 105 cryoablation applications were delivered through a 6-mm-tip cryothermal ablation catheter (Freezor Xtra, CryoCath) at predefined sites of the triangle of Koch.
Results:
Temporary effects on AV conduction were observed in 18 (19%) cryomapping and 38 (36%) cryoablation applications. Persistent effects were observed in 9 (9%) cryoablation applications. Persistent effects were associated with cryoablation at the superior third of the triangle of Koch (P = .05), nadir tip temperature < or = -79 degrees C (P = .007), and effect onset time < or =15 seconds (P = .03). Temperature and effect onset time remained statistically significant after multivariate adjustment (P = .01 and .02, respectively). Overall, persistent complete AV block was achieved with cryoenergy in only one patient. In two additional patients, AV conduction remained modified. In the remaining patients, persistent complete AV block was achieved with radiofrequency (median one application per patient).
Conclusion:
The low rate of persistent AV conduction impairment observed with attempts to cryoablate the AV node supports a great safety margin of perinodal cryothermal ablation.
Insights
Cryoablation of the atrioventricular (AV) node shows a high safety margin, with a low rate of persistent conduction impairment. This suggests cryothermal ablation is a safe option for AV nodal ablation procedures.
Area of Science:
- Electrophysiology
- Cardiovascular Medicine
- Medical Technology
Background:
- Animal studies and limited patient data suggest cryoenergy is safer than radiofrequency for ablating tissue near the AV node.
- Defining the safety margin of cryothermal ablation for AV nodal ablation is crucial for clinical practice.
Purpose of the Study:
- To systematically assess the electrophysiologic effects of cryoenergy on the human AV node.
- To establish the safety profile of cryothermal ablation in the AV nodal region.
Main Methods:
- 15 patients undergoing AV nodal ablation received 94 cryomapping and 105 cryoablation applications.
- A 6-mm-tip cryothermal ablation catheter was used at specific sites within the triangle of Koch.
Main Results:
- Temporary AV conduction effects occurred in 19% of cryomapping and 36% of cryoablation applications.
- Persistent effects were noted in 9% of cryoablation applications, associated with specific locations and temperatures (< -79°C) and onset times (< 15s).
- Complete AV block was achieved with cryoenergy in only one patient; radiofrequency was used for definitive block in others.
Conclusions:
- Cryoablation of the AV node demonstrates a favorable safety margin due to a low incidence of persistent conduction abnormalities.
- Perinodal cryothermal ablation appears to be a safe therapeutic option for AV nodal ablation.
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