Cryothermal ablation of supraventricular tachycardia

Cryothermal ablation of supraventricular tachycardia requires special equipement for cooling the cryocatheter. Initially cryomapping is done with a slow decrease of the temperature to – 30°C up for 80 seconds. If mapping is successful, cryoablation with faster decrease of the temperature to –75°C for up to 480 seconds is done to produce the permanent lesion. Duration of application is significantly longer than for radiofrequency energy. “Cryoadherence” effect is the tight adherence of the catheter tip to the tissue caused by cooling. This has the great advantage of lack of catheter tip movement during the ablation period, which is a problem in radiofrequency catheter ablation when the catheter tip can move away from the target site due to cardiac motion. Another advantage of cryoablation is the reversibility of lesions which occur during cryomapping so that even if inadvertant AV block occurs during cryopmapping, it can be reversed by warming up on stopping the cryosource. For the same reason, recurrence rate is higher with cryoablation. Cryoablation is best suited for ablation in children where the conduction system is physically small and chance for complete heart block is higher.