Wide complex tachyarrhythmias refer to abnormal rapid heart rhythms characterized by widened QRS complexes on an electrocardiogram (ECG). These arrhythmias can be life-threatening and require prompt evaluation and management. The etiology, clinical features, and management strategies for stable and unstable patients differ, and in some cases, an electrical storm may occur, necessitating advanced interventions like dual sequential defibrillation.
Etiology:
Wide complex tachyarrhythmias can have various causes, including:
Ventricular Tachycardia (VT): Most common cause, often associated with structural heart disease, myocardial infarction, or scar tissue. Appropriate medical care is to assume that any wide complex tachycardia is VT until proven otherwise.
Supraventricular Tachycardia (SVT) with Aberrancy: When a supraventricular origin rhythm encounters a conduction abnormality, it may result in a wide complex appearance on the ECG.
Pre-excited Atrial Fibrillation: In the presence of an accessory pathway (WPW), atrial fibrillation can conduct rapidly to the ventricles, leading to a wide QRS complex.
Management for Stable Patients:
Identification of Underlying Cause: Determine if the arrhythmia is ventricular or supraventricular in origin.
Antiarrhythmic Medications: Administer medications such as amiodarone, procainamide, or lidocaine depending on the underlying rhythm.
Amiodarone (preferred agent in setting of AMI or LV dysfunction) – dosing is 150mg over 10min, followed by 1mg/min drip over 6 hr.
Procainamide is a potential agent. Did better in the PROCAMIO trial over amiodarone. Initial dosing is 20-50mg/min until arrythmia breaks (max 17mg/kg or 1 gram) then maintenance of 1-4mg/min x 6hr.
Electrolyte Correction: Address any electrolyte imbalances, especially potassium and magnesium.
Management for Unstable Patients:
Immediate Cardioversion: Synchronized electrical cardioversion is the treatment of choice. The usual dosage for synchronized cardioversion is 100-200J. (Note if the patient loses a pulse, in conjunction with started ACLS, the treatment option becomes unsynchronized cardioversion, or defibrillation).
IV Antiarrhythmic Medications: Amiodarone or procainamide may be administered while preparing for cardioversion. Lidocaine is also a potential agent.
Advanced Cardiovascular Life Support (ACLS): Follow ACLS guidelines for managing cardiac arrest, including chest compressions and airway management.
Electrical Storm and Dual Sequential Defibrillation:
An electrical storm is a term used to describe the occurrence of multiple sustained ventricular arrhythmias within a short period. It is a life-threatening situation that may be refractory to standard treatments.
Dual Sequential Defibrillation (DSD):
In cases of resistant ventricular arrhythmias, dual sequential defibrillation involves using two defibrillators almost simultaneously to deliver two shocks.
The goal is to increase the energy delivered to the heart, potentially terminating the arrhythmia.
This approach is considered in refractory cases where conventional defibrillation has failed.
Procedure for DSD:
1. Apply both sets of pads, adjacent to one another, and not touching (see the diagram from RebelEM).
2. Charge both monitors to max dosage (200J for biphasic, 360J for monophasic).
3. Charge and simultaneously activate the defibrillation/shock button on each monitor.
4. Continue with compressions and ACLS.
5. Consider a beta-blocker (esmolol) bolus, and consider holding epinephrine dosing to limit cardiac excitation.
Sources:
https://rebelem.com/dual-sequential-defibrillation-dsd/
https://pubmed.ncbi.nlm.nih.gov/27354046/