ACLS review: Wide Complex Tachycardia (WCT) Part 7

Proarrhythmias

·         Serious tachyarrhythmias or bradyarrhythmias seemingly generated by antiarrhythmic agents

·         The interactions between agents are complex. Sequential use of 2 or more antiarrhythmic drugs compounds the adverse effects, particularly for bradycardia, hypotension, and torsades de pointes

Proarrhythmias

·         tachyarrhythmias account for most proarrhythmia events.

·         torsades de pointes accounts for the majority of tachycardic proarrhythmic episodes

·         when an appropriate dose of a single antiarrhythmic medication fails to terminate an arrhythmia, turn to electrical cardioversion rather than a second antiarrhythmic

Recommended Synchronized Cardioversion Joule Settings

·         SVT, Atrial flutter            50-100J  

·         Stable VT                       100J 

·         Atrial fibrillation              120-200J 

·         Polymorphic VT             200J (unsynchronized) 

Synchronized cardioversion of Stable VT

·         Biphasic  begin at 100J and increase joules setting on subsequent shocks as needed

·         Monophasic begin at 200J and increase in a stepwise fashion

Note:  Monomorphic VT (regular form and rate) with a pulse responds well to monophasic or biphasic waveform cardioversion (synchronized) shocks at initial energies of 100 J. If there is no response to the first shock, it may be reasonable to increase the dose in a stepwise fashion. No studies were identified that addressed this issue. Thus, this recommendation represents expert opinion (Class IIb, LOE C).

Synchronized cardioversion

·         Specific timed delivery of electrical shock to the heart

·         Treatment of choice for SVT, VT with a pulse and atrial flutter with evidence of poor profusion

·         Provide sedation and analgesia

·         Prepare to defibrillate immediately if cardioversion causes VF

Note:  Synchronized cardioversion is shock delivery that is timed (synchronized) with the QRS complex. This synchronization avoids shock delivery during the relative refractory period of the cardiac cycle when a shock could produce VF.

Indications

·         All tachycardias (rate >150 bpm) with serious signs and symptoms related to the tachycardia.  These include unstable SVT, atrial flutter, atrial fibrillation and unstable VT

·         May give brief trial of medications based on specific arrhythmias.

Note:  Cardioversion is less likely to be effective for treatment of junctional tachycardia or ectopic or multifocal atrial tachycardia because these rhythms have an automatic focus, arising from cells that are spontaneously depolarizing at a rapid rate

Precautions

·         In critical conditions go to immediate unsynchronized shocks.

·         Urgent cardioversion is generally not needed if heart rate is over 150 bpm.

·         Reactivation of sync mode is required after each attempted cardioversion (defibrillators/cardioverters default to unsynchronized mode).

·         Prepare to defibrillate immediately if cardioversion causes VF.

·         Synchronized cardioversion cannot be performed unless the patient is connected to monitor leads; lead select switch must be on lead I, II, or III and not on “paddles.”

Preparation

·         Airway: Establish appropriate airway management. Suction equipment on hand

·         B Breathing: Provide O2. Assess adequacy of ventilation.  Monitor oxygen saturation

·         C Circulation: IV access. Attach monitor leads and Combo pads

Technique

·         Premedicate whenever possible.

·         Engage sync mode before each attempt.

·         Look for sync markers on the R wave.

·         Set recommended joule setting

·         Press “charge” button, “clear” the patient, and press the “shock” button.

Ventricular Tachycardia with synch markers

Cardioversion of Ventricular Tachycardia

Technique

·         Observe for rhythm change on monitor.

·         Observe patient’s ABCs post procedure

Expert consultation

·         Seek expert consultation for tachycardias not responsive to medications

·         Seek consultation for long term management

Reviewed 2/28/16