General anesthesia in spontaneous respiration with intravenous ketamine in patients undergoing pulsed-field ablation

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND: Thermal ablation of atrial fibrillation (AF) by means of radiofrequency or cryo-balloon is usually performed under general anesthesia, deep sedation, or conscious sedation at operator’s discretion and based on the general condition of the patient. However, a standardized sedation protocol when performing a non-thermal ablation, such as pulsed-field ablation (PFA) through irreversible cellular electroporation, has not been well established. PURPOSE: We report our preliminary experience of a general anesthesia in spontaneous respiration protocol with ketamine used at a high-volume center during ablation of AF with a new PFA system. METHODS: All consecutive patients (pts) undergoing AF ablation with PFA at our center were included. Our sedation protocol consists of intravenous administration of midazolam (1+1 mg), fentanyl (25+25+25+25 mcg/kg) at low doses before local anesthesia with lidocaine (200mg) administration. Patients underwent sedation under spontaneous respiration by administering oxygen (4-6 l/min) through a face mask with nasal cannula. Local anesthesia was performed before the percutaneous femoral venous access. Soon after the trans-septal puncture, heparin (1 mg/kg) and atropine (1 mg, to mitigate anticipated bradycardia) were injected, followed by a second bolus of midazolam (1 mg). Ketamine adjunct (1 mg/kg) was then injected about 5 minutes before the first PFA delivery which was titrated to effect based on patient’s condition, response and changes in vital signs (total ketamine adjunction of 2 mg/kg). For quantitative assessment the Numeric Rating Scale for Pain (NRS) was applied. For qualitative assessment a 3-levels satisfaction evaluation was retrieved. The ablation endpoint was PVI as assessed by entrance and exit block. RESULTS: Forty-two pts were included in this analysis (mean age of 66±9 years,72% were male, CHA2DS2VASc score=2 [IQR 1–3], median body mass index 24[20-48]kg/m2, 35% had respiratory diseases – e.g. asthma, OSAS, COPD –). At baseline, before sedation, mean systolic blood pressure was 140.5+20.1mmHg and mean oxygen saturation was 97.9+2.1%. PVI was achieved in all the patients. The number of PFA applications to reach PVI was 33.4+3 (time to PVI = 25+4min). In two cases additional PFA lesion sets were deployed outside the PVs. Lab occupancy time was 122±32min, skin-to-skin time was 78±35min and fluoroscopy time was 23±14min. All the patients achieved a NRS ≤ 3. Satisfaction level was found to be acceptable in all procedures by both the patient and the primary operator (Score equal to 0). No major procedure-related adverse events were reported. CONCLUSION: The PFA procedure has a short execution time. The standardized anesthetic protocol with the administration of drugs with rapid onset and pharmacological offset at low doses was effective and safe with an optimal degree of patient and operator satisfaction.