High-Frequency Low-Tidal-Volume Ventilation During Atrial Fibrillation Ablation Improves Long Term Outcome

High-Frequency Low-Tidal-Volume Ventilation During Atrial Fibrillation Ablation Improves Long Term Outcome

Catheter ablation for pulmonary vein isolation is an important modality of treatment for paroxysmal atrial fibrillation. It is also useful for persistent atrial fibrillation, though a little less. Importance of maintaining a stable contact force of the catheter during radiofrequency ablation cannot overstressed as it contributes to lesion size and achieving transmural lesion. Both these are important in reducing re-connection of pulmonary veins, an important cause for recurrent atrial fibrillation after catheter ablation. General anaesthesia during procedure reduces the rate of pulmonary vein reconnection and hence recurrent atrial arrhythmia to some extent, by providing better catheter stability than conscious sedation. Still there is fluctuation in catheter stability during each breath in usual ventilation with tidal volumes of around 500 mL. Standard ventilation produces downward shift of diaphragm during inspiration, causing large fluctuation in catheter contact force. This also increases the risk of perforation, especially while ablating the roof of left atrium. It is because the catheter is placed in a vertical position and the diaphragm displaces the heart downwards against the catheter tip [1].

It is in this scenario that high frequency, low tidal volume ventilation comes in. It reduces catheter contact force oscillation and shortens procedure time than standard ventilation. High frequency, low tidal volume ventilation during pulmonary vein isolation is associated higher success during the first attempt itself. REAL-AF was a prospective multicenter registry of 661 patients undergoing ablation for paroxysmal atrial fibrillation using either high frequency, low tidal volume ventilation or standard ventilation [1]. Study concluded that high frequency, low tidal volume ventilation during catheter ablation improved freedom from all atrial arrhythmia recurrence, atrial fibrillation related symptoms and hospitalizations. Shorter procedure times were also documented.

High frequency, low tidal volume protocol typically had respiratory rate of 25-30 breaths/min and a tidal volume of 200 mL (3-3.5 mL/kg). The protocol was used only during ablation, to minimize the risk of carbon dioxide retention. End tidal carbon dioxide was maintained below 50 mm Hg. Hyperventilation or recruitment breaths were given between ablation sets if needed, to decease ETCO₂ to target levels. Standard ventilation was at 10-12 breaths/min and tidal volume of 6-8 mL/kg [1].

1. Osorio J, Zei PC, Díaz JC, Varley AL, Morales GX, Silverstein JR, Oza SR, D’Souza B, Singh D, Moretta A, Metzl MD, Hoyos C, Matos CD, Rivera E, Magnano A, Salam T, Nazari J, Thorne C, Costea A, Thosani A, Rajendra A, Romero JE. High-Frequency Low-Tidal-Volume Ventilation Improves Long-Term Outcomes in Atrial Fibrillation Ablation: A Multicenter Prospective Study. JACC Clin Electrophysiol. 2023 May 18:S2405-500X(23)00298-0. doi: 10.1016/j.jacep.2023.05.015. Epub ahead of print. PMID: 37294263.