What is the evidence for double sequential defibrillation (Double Sequential Shock) in ventricular tachycardia (VT)/ventricular fibrillation (VF) cardiac arrest?

From the Guidelines

Double sequential defibrillation (DSD) may be considered for refractory ventricular fibrillation/pulseless ventricular tachycardia (VF/pVT) after standard defibrillation attempts have failed, but its usefulness has not been established according to the 2020 American Heart Association guidelines 1. The evidence for DSD comes from observational studies and case reports suggesting improved rates of return of spontaneous circulation and survival in patients with refractory VF/pVT.

Key Considerations

• The 2020 American Heart Association guidelines state that the usefulness of double sequential defibrillation for refractory shockable rhythm has not been established (Class 2b, LOE C-LD) 1.
• A systematic review reveals that at least 20% of patients with ventricular fibrillation (VF)/pulseless ventricular tachycardia (pVT) will remain in a shockable rhythm after 3 shocks, and survival decreases as the number of defibrillation attempts required increases 1.
• To perform DSD, two defibrillators are used simultaneously or in rapid sequence, with one set of defibrillator pads in the standard anterior-posterior or anterior-lateral position, and the other set in an alternative position.
• Both defibrillators should be charged to their maximum energy setting (typically 200J for biphasic defibrillators), and the shocks are then delivered either simultaneously or within seconds of each other by two operators.

Important Notes

• DSD should only be considered after multiple standard defibrillation attempts, optimal CPR, and appropriate medication administration (including epinephrine and amiodarone) have failed to terminate VF/pVT.
• The theoretical benefit of DSD is that it may overcome high defibrillation thresholds by delivering more energy and creating multiple vectors of current through the myocardium, potentially terminating refractory arrhythmias.

Clinical Decision Making

• In clinical practice, the decision to use DSD should be made on a case-by-case basis, taking into account the individual patient's circumstances and the availability of resources.
• It is essential to weigh the potential benefits of DSD against the potential risks and to consider alternative treatment options, such as continuing standard defibrillation attempts or using other advanced life support interventions.

From the Research

Double Sequential Defibrillation in Ventricular Tachycardia/Ventricular Fibrillation Cardiac Arrest

• The evidence for double sequential defibrillation (DSD) in ventricular tachycardia (VT)/ventricular fibrillation (VF) cardiac arrest is limited and inconclusive 2, 3, 4, 5.
• A retrospective review of out-of-hospital cardiac arrests found that DSD was associated with similar rates of VF termination and return of spontaneous circulation (ROSC) compared to standard defibrillation, but earlier DSD may be associated with improved rates of VF termination and ROSC 2.
• A case report series found that DSD was successful in terminating refractory VF in three patients, suggesting that DSD may improve the chance of spontaneous circulation 3.
• A study on prehospital dual sequential defibrillation found that DSD was associated with lower odds of prehospital ROSC compared to conventional defibrillation, and no differences in survival to hospital admission, 72 hours, or hospital discharge 4.
• A systematic review found no differences in neurological outcome, survival to hospital discharge, survival to hospital admission, ROSC, or termination of VF/pVT between DSD and standard defibrillation, but noted that the current literature has limitations and further high-quality evidence is needed 5.
• A randomized controlled trial is currently underway to compare DSD and vector change defibrillation to standard defibrillation for patients with refractory VF or pulseless VT during out-of-hospital cardiac arrest 6.

Key Findings

• DSD may be associated with improved rates of VF termination and ROSC when used early in the treatment of refractory VF 2.
• DSD is not associated with improved outcomes from out-of-hospital cardiac arrest, but the current literature has limitations and further high-quality evidence is needed 5.
• A well-designed randomized controlled trial is required to determine if DSD or vector change defibrillation impact clinical outcomes 6.

Study Limitations

• The current evidence is limited by small sample sizes, retrospective designs, and variability in defibrillation protocols 2, 3, 4, 5.
• Further high-quality evidence is needed to fully understand the effectiveness of DSD in VT/VF cardiac arrest 5, 6.