Background: Cryoenergy as a modality for transcatheter ablation has been well established in the last decade. Direct cell injury from freezing manifests sometimes in a delayed manner. We present two clinical cases of a delayed effect of cryoablation in perinodal tissue.
Methods and Results: A 37 y female, without structural heart disease, presented with numerous repetitive parahisian extrasystoles highly symptomatic. We conducted a detailed mapping of AV node with the Carto system and we performed cryoablation. After each lesion we noted junctional beats partially different from the original arrhythmia. At one month follow-up the patient didn’t present any extrasystoles.
We performed cryoablation of a medioseptal accessory pathway in a 14 y male with preexcitation (the effective refractory period of the by-pass tract was 240msec). Two hours after ablation the patient presented evidence of preexcitation. Nevertheless, at one month follow-up there was no evidence of preexcitation.
Conclusions: We describe two clinical cases of delayed effects of cryoablation in perinodal tissue. These effects are likely secondary on apoptotic cell death occurring after application of cryoenergy. Further studies are needed to exclude other possible mechanisms.