[Catheter cryoablation for the treatment of supraventricular arrhythmias]. / La cryoablation endocardiaque percutanée dans le traitement des arythmies supraventriculaires.

ABSTRACT

Catheter ablation is a radical treatment for various severe and drug-refractory arrhythmias. Radiofrequency is the reference energy for ablation, but has some limitations. Cryoenergy gradually freezes myocardial tissue, allowing the consequences to be predicted before inducing the lesion. Furthermore, the lesions are better-circumscribed and less thrombogenic than those induced by radiofrequency. Twenty-two patients (12 women) aged from 20 to 79 years with drug-refractory supraventricular arrhythmias underwent cryoablation. The ablation catheter was cooled by nitrous oxide expansion. The electrophysiological properties of the tissue are reversibly lost at a temperature of -30 degrees C, allowing cryomapping. When the appropriate target has been located, the temperature is reduced to -70 degrees C. The cryoablation is painless. The procedure was initially successful in all 12 patients with atrionodal reentrant tachycardias, usually after one or two applications. However, during the 8-month follow-up period, slower, transient tachycardia recurred in 3 patients. We observed no cases of atrioventricular (AV) block, a possible complication of radiofrequency. Cryoablation was successful and safe in two patients with an accessory pathway (Kent). In eight patients with atrial fibrillation and uncontrolled ventricular tachycardia, cryoablation was used with the aim of slowing nodal conduction. Initial success was obtained in 7 cases (3 modulations and 4 complete AV blocks) but only persisted in four cases, suggesting that more applications should be used or different sites targeted. The efficacy and safety of cryoablation make it an attractive option for the ablation of small substrates close to the nodo-Hisian tissue (atrionodal reentries and accessory pathways). New criteria must be developed to define long-term success of cryoablation of the AV node, which is successful in the acute setting.