What is the procedure for performing double sequential cardioversion?

Double Sequential Cardioversion Procedure

Double sequential cardioversion is a technique used for refractory ventricular tachycardia or fibrillation when standard cardioversion attempts have failed, involving the use of two defibrillators to deliver shocks in rapid succession.

Standard Cardioversion Procedure (For Context)

Before considering double sequential cardioversion, standard cardioversion should be attempted:

• Perform cardioversion with the patient in a fasting, post-absorptive state under sedation or general anesthesia 1
• Maintain adequate ECG monitoring throughout the procedure 1
• Place electrodes (paddles or pads) in anteroposterior or base-apex location 1
• For atrial defibrillation, a more superoanterior left paddle position is often more effective 1
• Ensure synchronization to the peak of the QRS complex (never deliver shock on the T-wave) 1
• For atrial fibrillation, initial shock energy of 200 J or greater is recommended when using biphasic defibrillators 1
• If conversion is unsuccessful, repeat with higher energy 1

Double Sequential Cardioversion Technique

When standard cardioversion fails to terminate refractory arrhythmias, double sequential cardioversion may be considered:

Equipment Setup

• Two separate defibrillators are required 2
• First defibrillator: place pads in standard anterior-lateral position 3
• Second defibrillator: place pads in anterior-posterior position 3

Procedure Steps

1. Ensure proper sedation or anesthesia is maintained 1
2. Set both defibrillators to synchronized mode (for ventricular tachycardia with pulse) 2
3. Charge both defibrillators to the desired energy level 2
4. Deliver the first shock from one defibrillator 2
5. Immediately follow with the second shock from the other defibrillator (within seconds) 2
6. Assess rhythm and hemodynamic response 2

Energy Settings

• Both defibrillators are typically set to deliver maximum energy (usually 200J each with biphasic defibrillators) 3
• The combined effect provides higher total energy delivery than a single defibrillator can achieve 4

Indications and Considerations

• Primary indication is refractory ventricular tachycardia or fibrillation that has not responded to multiple standard cardioversion attempts 2
• Consider this technique after 3-5 unsuccessful standard defibrillation attempts 4
• May be considered before or after administration of antiarrhythmic medications like amiodarone 2
• Particularly useful when rapid restoration of sinus rhythm is needed and antiarrhythmic medications might worsen hypotension 2

Important Cautions

• This is considered an off-label use of defibrillators and is not currently part of published advanced cardiac life support guidelines 5
• May cause damage to the defibrillator equipment 5
• Manufacturer's warranty may be voided by this off-label use 5
• Limited evidence exists for improved survival outcomes 3
• Some studies suggest lower odds of prehospital return of spontaneous circulation with this technique compared to conventional defibrillation 3

Alternative Approaches

• Internal cardioversion may be considered when external cardioversion fails 1
• Administration of antiarrhythmic medications (amiodarone, ibutilide) before subsequent cardioversion attempts may lower defibrillation threshold 1, 6
• Repositioning of electrodes between attempts may improve success rates 6

Post-Procedure Management

• Monitor for potential complications including ventricular arrhythmias, asystole, and transient myocardial depression 1
• Be prepared to manage these complications with appropriate medications and interventions 1
• Continue appropriate anticoagulation if cardioverting atrial fibrillation 1

Double sequential cardioversion should be considered an advanced rescue technique for life-threatening situations when standard approaches have failed, with awareness of its limited evidence base and potential equipment risks.