Cryoablation of the Retrograde Fast Pathway as Treatment for AVNRT

Cryoablation of the Retrograde Fast Pathway as Treatment for AVNRT

In this study a new technique for ablation in atrioventricular nodal reentrant tachycardia using cryo-energy will be studied in cases where the standard approach has higher risk.

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common cause of fast heartbeats in young people. People with AVNRT have two pathways within the heart, the fast pathway (FP) and slow pathway (SP). A treatment for AVNRT is ablation (burning or freezing) of the SP. This can be done with either radiofrequency or cryo-energy. A complication which occurs in 1% of cases is AV block (AVB), meaning the person needs a pacemaker.

Slow pathway ablation is a problem in people when the electrocardiogram (ECG) shows a long PR interval, with greater rates of AVB. This accounts for 5% of AVNRT cases. A possible solution is to treat the FP with cryo-energy and leave the SP intact. This pilot study aims to show this is safe and effective.

Inclusion Criteria:

• Documented supraventricular tachycardia (SVT)
• Planned to undergo electrophysiology (EP) study and ablation
• PR interval on ECG <220ms (Group 1) or >220ms (Group 2)

Exclusion Criteria:

• Pregnancy
• Age <18 years
• Inability to provide consent
• High likelihood of tachycardia mechanism other than AVNRT (e.g. Pre-excitation on surface ECG, atrial tachycardia)