Investigating Deep Sedation With Intravenous Ketamine in Spontaneous Respiration During Pulsed-Field Ablation.

OBJECTIVES: The authors report their experience of a protocol for deep sedation with ketamine in spontaneous respiration during the pulsed-field ablation (PFA) of atrial fibrillation (AF). DESIGN: Observational, prospective, nonrandomized fashion. SETTING: Single-center hospitalized patients. PARTICIPANTS: All consecutive patients undergoing PFA of AF. INTERVENTIONS: Patients undergoing deep sedation with intravenous ketamine. MEASUREMENTS AND MAIN RESULTS: The authors' sedation protocol involves the intravenous administration of fentanyl (1.5 µg/kg) and midazolam (2 mg) at low doses before local anesthesia with lidocaine. A ketamine adjunct (1 mg/kg) in 5-minute boluses was injected about 5 minutes before the first PFA delivery. The authors enrolled 117 patients (age = 59 ± 10 y, 74.4% males, body mass index = 27.6 ± 5 kg/m2, fluoroscopy time = 24 ± 14 minutes, skin-to-skin time = 80 ± 40 minutes and PFA LA dwell time = 24 ± 7 minutes). By the end of the procedure, pulmonary vein isolation had been achieved in all patients using PFA alone. The mean time under sedation was 54.9 ± 6 minutes, with 92 patients (79%) being sedated for <1 hour. A satisfactory Ramsay Sedation Scale level before ketamine administration was achieved in all patients, except one (80.3% of the patients with rank 3; 18.4% with rank 2). In all procedures, the satisfaction level was found acceptable by both the patient and the primary operator (satisfactory in 98.2% of cases). All patients achieved a Numeric Rating Scale for Pain ≤3 (none or mild). No major procedure or anesthesia-related complications were reported. CONCLUSION: The authors' standardized sedation protocol with the administration of drugs with rapid onset and pharmacologic offset at low doses was safe and effective, with an optimal degree of patient and operator satisfaction.

Is the mid-diastolic isthmus always the best ablation target for re-entrant atrial tachycardias?

AIMS: We evaluated the ability of an ultrahigh mapping system to identify the most convenient Rhythmia ablation target (RAT) in intra-atrial re-entrant tachycardias (IART) in terms of the narrowest area to transect to interrupt the re-entry. METHODS: A total of 24 consecutive patients were enrolled with a total of 26 IARTs. The Rhythmia mapping system was used to identify the RAT in all IARTs. RESULTS: In 18 cases the RAT matched the mid-diastolic phase of the re-entry whereas in 8 cases the RAT differed. In these patients, the mid-diastolic tissue in the active circuit never represented the area with the slowest conduction velocity of the re-entry. The mean conduction velocity at the mid-diastolic site was significantly slower in the group of patients in which the RAT matched the mid-diastolic site (P = 0.0173) and that of the remaining circuit was significantly slower in the group in which the RAT did not match (P = 0.0068). The mean conduction velocity at the RAT was comparable between the two groups (P = 0.66). CONCLUSION: Identifying the RAT in challenging IARTs by means of high-density representation of the wavefront propagation of the tachycardia seems feasible and effective. In one-third of cases this approach identifies an area that differs from the mid-diastolic corridor.

Inducibility of ventricular arrhythmia and tachyarrhythmia recurrences in patients with implantable defibrillator.

INTRODUCTION: We evaluated the potential ability of the electrophysiological (EP) inducibility of ventricular arrhythmias to predict the likelihood of appropriate ICD intervention over the long-term in ischemic and nonischemic patients with current primary prevention indications for ICD implantation. METHODS: Between 2006 and 2008, 206 consecutive heart failure patients who were candidates for ICD implantation for the primary prevention of sudden cardiac death according to standard indications underwent EP testing, usually on ICD implantation. RESULTS: On EP testing, 15 (7%) patients had inducible monomorphic ventricular tachycardia (VT) and 14 (7%) ventricular fibrillation (VF). Over 24 months, 64 (31%) patients received appropriate ICD therapies: 51 (25%) for VT and 16 (8%) for VF. The time to the first appropriate ICD therapy trended to be shorter in the group of patients who were inducible on EP testing (p=0.072). Among patients receiving appropriate therapies, the median number of arrhythmic episodes was 2, and the proportion of patients with 2 treated arrhythmic episodes was higher in the group of inducible patients (34% versus 14%, p=0.005). On multivariate analysis, inducibility proved to be an independent predictor of frequent (2) arrhythmic episodes, as did a history of coronary artery bypass grafting. Moreover, patients with 2 treated arrhythmic episodes showed higher mortality (log-rank test, p=0.042). CONCLUSION: Patients with inducibility of VT or VF are more likely to experience frequent appropriate ICD therapies during follow up.