Initial energy for external electrical cardioversion of atrial fibrillation

The Impact of Personal Thoracic Impedance on Electrical Cardioversion in Patients with Atrial Arrhythmias

Background and Objectives: Direct current cardioversion (DCCV) is a safe and useful treatment for atrial tachyarrhythmias. In the past, the energy delivered in DCCV was decided upon empirically, based only on the type of tachyarrhythmia. This conventional method does not consider individual factors and may lead to unnecessary electrical damage. Materials and Methods: We performed DCCV in patients with atrial tachyarrhythmias. The impedance and electrical current at the moment of shock were measured. The human thoracic impedance between both defibrillator patches and the electric current that was used were measured. Results: A total of 683 DCCVs were performed on 466 atrial tachyarrhythmia patients. The average impedance was 64 ± 11 Ω and the average successful current was 23 ± 6 mA. The magnitude of the electrical current that was successful depended upon the human impedance (linear regression, B = −0.266, p < 0.001) and the left atrial diameter (B = 0.092, p < 0.001). Impedance was directly proportional to body mass index (BMI) (B = 1.598, p < 0.001) and was higher in females than in males (77 ± 15 Ω vs. 63 ± 11 Ω, p < 0.001). Notably, the high-impedance (>70 Ω) group had a higher BMI (27 ± 4 kg/m² vs. 25 ± 3 kg/m², p < 0.001) and a higher proportion of females (37% vs. 9%, p < 0.001) than the low-impedance group (<70 Ω). However, thoracic impedance was not an independent predictor for successful DCCV. Conclusions: Human thoracic impedance was one of the factors that impacted the level of electrical current required for successful DCCV in patients with atrial arrhythmias. In the future, it will be helpful to consider individual predictors, such as BMI and gender, to minimize electrical damage during DCCV.

Propofol for sedation for direct current cardioversion

Direct current cardioversion is a low-risk and standard procedure to restore normal sinus rhythm in patients with tachyarrhythmias. It requires sedation to facilitate the procedure, as it is painful and distressful. The preferred anesthetic drug must be short acting, producing conscious sedation, to enable rapid recovery after the procedure. In this sense, this narrative review focuses on the critical analysis of recent randomized studies and presents about the safety and effectiveness of propofol, comparing it with other established sedatives, mainly etomidate and midazolam. The research was performed on MEDLINE database with Propofol and Cardioversion keywords. In most cases, propofol comes to be the best option, with a quick recovery time and low rates of side effects. Different studies have demonstrated no inferiority when comparing to other drugs and, when these adverse events happened, they were easily and quickly handled. Exceptions in this scenario are those patients, particularly the elderly, with baseline important structural heart disease, in which etomidate with fentanyl has been pointed to lead to better hemodynamic stability.