In this randomized study, two energy sources for the ablation of AV nodal reentry tachycardia are compared: The standard technique of radiofrequency energy delivery is compared with the new approach of cryo-energy application.

The ablation of AV nodal reentry tachycardia with radiofrequency (RF) energy delivering catheters is a standard procedure and in experienced EP laboratories, the safety and efficacy of this approach is very high.

However, the potential complication of higher degree AV conduction block, requiring in some instances implantation of a pacemaker, is a major drawback of this approach.

We want to compare in this randomized study the safety and efficacy of standard RF ablation with the cryo-ablation technique. This relatively new technique is thought to offer more safety concerning higher degree AV conduction block.

Inclusion Criteria:

• Age between 18 and 80 years old
• Clinical diagnosis of AVNRT (ECG/patients history)
• Electrophysiologically confirmed (invasively assessed) diagnosis of AVNRT
• Written informed consent

Exclusion Criteria:

• Prior ablation for AVNRT
• Congenital heart disease interfering with the ablation method
• Prior cardiac surgery
• Medical or psychiatric disorder interfering with study protocol or data acquisition
• Exclusion of the patient by the study investigator