Cryofreezing catheter ablation of adenosine triphosphate sensitive atrial tachycardia

Abstract

Introduction Adenosine triphosphate (ATP) sensitive atrial tachycardia (AT) has been treated by radiofrequency catheter ablation. Cryofreezing energy has emerged as a novel energy source for catheter ablation. The aim of this study was to investigate the efficacy and safety of cryofreezing ablation for ATP‐sensitive AT. Methods and Results A total of six patients with ATP‐sensitive ATs were included in this study. A single atrial extrastimulation was able to initiate and terminate these ATs in all six patients. The electrophysiological findings satisfied the diagnostic criteria of ATP‐sensitive AT. The ablation catheter was located at the earliest activation site of atrial excitation during the AT, and cryofreezing energy was delivered through a cryoablation catheter to perform cryomapping at temperature of −30 or −80°C. When cryomapping successfully terminated the ATs, cryoablation at a temperature of −80°C was subsequently performed. The earliest atrial activation during AT was recorded at the Koch's triangle area associated with a distinct intra‐atrial activation sequence from that recorded during ventricular pacing. Cryoablation was performed at successful cryomapping sites and resulted in the complete elimination of the AT in all six patients without affecting the bidirectional atrioventricular (AV) nodal conduction. Conclusion Cryofreezing energy was safe and effective in treating ATP‐sensitive ATs even in patients with its origins located in the vicinity of the AV node.

Does cryomapping warrant a safety in the subsequent therapeutic cryoablation?

“…Ablation targeting at the earliest activation site per se is the same as used in the radiofrequency catheter ablation for the same tachycardia. For cryomapping, two attempts were made in this study: one was CM‐30 in which cryothermal energy at a halfway low temperature (−30°C) was applied, and the other CM‐80 in which cryothermal energy at an adequately low temperature (−80°C) was for a short duration (within 10 seconds) . Although the number of the patients treated was limited to six cases, this “test” application, which is not available in radiofrequency ablation would be useful and important, especially in patients with the earliest activation site close to the critical AV node area.…”

“…In this issue of the Journal of Cardiovascular Electrophysiology , Okishige et al first reported the effect of the catheter‐based cryoablation in patients with ATP‐sensitive atrial tachycardia, paying special attention to the predictive value of cryomapping as well as the effectiveness and safety of cryoablation. Of a total of 37 patients with focal atrial tachycardia treated between April 2016 and September 2018, the consecutive six patients with ATP‐sensitive atrial tachycardia originating from the Koch' triangle consisted of this study.…”

“…This study demonstrated not only the effectiveness and safety of cryoablation targeting the earliest activation site in ATP‐sensitive atrial tachycardia but the usefulness of cryomapping in determining the target ablation site while avoiding the adverse AV conduction impairment . Ablation targeting at the earliest activation site per se is the same as used in the radiofrequency catheter ablation for the same tachycardia.…”

“…It should be emphasized, however, that cryomapping indeed is useful in identifying an effective ablation site but does not necessarily warrant a safety in the subsequent therapeutic cryoablation, which is applied at a much lower temperature and for a longer duration and thus may create a more robust lesion. In fact, cryoablation was prematurely interrupted in one case in which Wenckebach type AV block developed during freezing . As discussed by the authors, cryomapping did not always guarantee safety in the subsequent cryoablation applied to the critical area, and therefore, careful observation during cryothermal energy application is required.…”

“…10 In this issue of the Journal of Cardiovascular Electrophysiology, This study demonstrated not only the effectiveness and safety of cryoablation targeting the earliest activation site in ATPsensitive atrial tachycardia but the usefulness of cryomapping in determining the target ablation site while avoiding the adverse AV conduction impairment. 11 Ablation targeting at the earliest activation site per se is the same as used in the radiofrequency catheter ablation for the same tachycardia. For cryomapping, two attempts were made in this study: one was CM-30 in which cryothermal energy at a halfway low temperature (−30°C) was applied, and the other CM-80 in which cryothermal energy at an adequately low temperature (−80°C) was for a short duration (within 10 seconds).…”