What are the AV ratios for Cryo and RF ablations in AVNRT?

• A. Cryo 1:1/1:3; RF 1:4/1:8
• B. Cryo 1:4/1:8; RF 1:1/1:3
• C. Cryo 1:2/1:5; RF 1:3/1:6
• D. Cryo 1:1/1:3; RF 1:2/1:4

Answer: (A)

In AVNRT ablation, the atrial-to-ventricular (AV) ratio describes the relative size of the atrial and ventricular electrograms recorded at the ablation site. This helps identify the tissue region you’re targeting while avoiding injury to the AV node. Cryo ablation tends to be applied in areas where the atrial and ventricular signals are more balanced, so the AV ratio sits in the lower range, around 1:1 to 1:3. Radiofrequency ablation, which creates deeper and more extensive lesions, often yields a relatively larger ventricular component at the target, pushing the AV ratio toward higher values, roughly 1:4 to 1:8. Therefore, the best match is Cryo with AV ratios about 1:1 to 1:3 and RF with AV ratios about 1:4 to 1:8. This aligns with the practical observation that cryo targets near the slow pathway with more balanced signals, while RF tends to show a more ventricular-dominant ratio at effective sites. The other options would swap or misplace these ranges, not reflecting the typical relationship between modality, tissue effect, and recorded electrograms in AVNRT ablation.