Irregular Wide Complex Tachycardia: Vtach?

​HPI: Teenage female with SOB, presyncope, and palpitations x 1 hour.  HR is 220 in triage. BP 118/84, RR 28, SpO2 96%. Alert and oriented.
 
EKG:

Question:  What arrhythmia is this? How you would treat this rhythm in a stable patient. What if the patient were unstable?
 
 
ECG Interpretation: Rate of 173/min.  Irregularly irregular rhythm, wide complex tachycardia with intermittent narrow complexes and changing of QRS morphologies. No LBBB or RBBB pattern.
 
Diagnosis: Afib with WPW
 
Let’s discuss the interpretation of irregularly irregular Wide Complex Tachycardias (WCT), and then we will discuss the treatment.
 
At first glance, it is difficult to assess the regularity, but with some scrutiny, you can see that the rhythm is irregular. The differential diagnosis of irregularly irregular WCT is essentially limited to three main dysrhythmias. Dr. Littmann calls these FBI: Fast, Broad, and Irregular:

• Afib with LBBB
• Afib with RBBB
• Afib with WPW

​The above ECG is an irregularly irregular WCT meeting the criteria for LBBB as below (upgoing in I, deep S waves in V1). Note the rate of 134. Fast, but not extremely fast, indicating likely transmission through the AV node.

​Consider RBBB, looking for triphasic QRS, with rSR’ and 2nd upgoing phase wider and taller than first upgoing phase as shown in these images:

So we have scrutinized our irregularly irregular WCT and found no evidence of BBB pattern. We are now left with Afib with WPW. Why is this important? The treatment is completely different from regular WCT (usually Vtach) and Afib with BBB pattern.
 
Treatment of FBI, Fast Broad and Irregular:

• Unstable
  • DC Cardioversion!
• Stable
  • IV PROCAINAMIDE, 18-20 mg/kg at 20-30 mg/min (slow)
  • IV Ibutilide
  • Avoid all AV nodal blockers!
    • Adenosine
    • Verapamil
    • Diltiazem
    • Beta-blockers
    • Digoxin
    • Amiodarone (has both beta-blocker and Ca-channel blocker properties)
  • May consider DC Cardioversion if procainamide or ibutilide are unavailable
  • Some sources (e.g. 10-second EM app) suggest amiodarone for "polymorphic or irregular" WCT. Amiodarone was once the first-line treatment for irregular WCT, but there have been many poor outcomes associated with this. Treatment with amiodarone and other AV nodal blockers has resulted in patient decompensation including reports of death on multiple occasions.

Discussion:

• Recall that WPW causes an accessory electrical pathway which allows impulses to bypass the AV node, resulting in tachydysrhythmias. Most commonly, this causes a reentrant tachycardia (70-80%), which is managed as any other SVT. Adenosine is appropriate in these patients as it blocks the reentrant rhythm and allows a normal sinus rhythm to resume. 10-30% of the time, though, atrial fibrillation occurs as we have discussed. In Afib, rates can be >200 bpm, which is rarely seen in the absence of accessory pathways (recall max sinus heart rate estimation using 220 minus age). Any tachydysrhythmia with rate > 200 should raise suspicion for an accessory pathway. Constantly changing QRS morphology should also lead you to consider WPW with Afib.
• If the AV node is blocked in a patient with WPW who is in Afib, Vfib or asystole can and have occurred, unfortunately at times in young, healthy patients.

 
Key Points:

• Consider WPW with Afib in any Fast, Broad, Irregular (FBI) rhythm without signs of BBB pattern, especially if rate is excessive (>180)
• Treatment of stable WPW with Afib is procainamide or ibutilide. Don’t block the AV node! Cardiovert if unstable.
• In a patient with known WPW with a regular narrow complex rhythm (SVT), standard SVT treatment is appropriate

 
As a reminder for recognizing WPW in the non-tachycardic patient’s ECG:

References:

• Amal Mattu’s video lecture on Afib with WPW: https://www.youtube.com/watch?v=3Opx1XMA-yo
• Dr. Littmann’s ECG lectures
• FOAMCAST.org Episode 15 on Afib/Flutter: http://foamcast.org/2014/09/21/episode-15-atrial-fibrillationflutter/
• Boriani, Giuseppe et al. 'Ventricular Fibrillation After Intravenous Amiodarone In Wolff-Parkinson-White Syndrome With Atrial Fibrillation'. American Heart Journal 131.6 (1996): 1214-1216. Web.
• Marius A. Tijunelis and Mel E. Herbert (2005). Myth: Intravenous amiodarone is safe in patients with atrial fibrillation and Wolff–Parkinson–White syndrome in the emergency department. CJEM, 7, pp 262-265. doi:10.1017/S148180350001441X.

 
By:  Dean Tanner, PGY1 EM