A 44-year-old man presents to the emergency department with palpitations. He has a history of anxiety managed with fluoxetine and lorazepam. He also has hypertension but does not take any medications. Today, his symptoms have been persistent despite taking his medications. He says that he feels lightheaded and can’t walk. His temperature is 98.7°F (37.1°C), blood pressure is 120/72 mmHg, pulse is 183/min, respirations are 25/min, and oxygen saturation is 99% on room air. Physical exam reveals a somnolent and uncomfortable man. His pulse is rapid and regular. An ECG is performed as seen in Figure A. During the exam, the patient states that he feels lightheaded and appears occasionally somnolent. Which of the following is the most appropriate treatment for this patient?
Adenosine
Amiodarone
Procainamide
Cardioversion
Cardioversion
This patient is presenting with palpitations and an ECG demonstrating a wide complex tachycardia with a delta wave which are concerning for a tachydysrhythmia secondary to Wolff Parkinson White syndrome. Given his poor CNS perfusion (somnolence during his tachycardia despite a “normal” blood pressure), the most appropriate next step in management is cardioversion.

Wolff Parkinson White syndrome (WPW) is a pre-excitation syndrome where an accessory electrical pathway exists between the atria and ventricles that bypasses the AV node. WPW can demonstrate antidromic conduction where the accessory pathway leads to anterograde conduction causing a wide-complex tachycardia that is often mistaken for ventricular tachycardia. In this circumstance, the QRS is wide and a delta wave is often present but may be difficult to discern. If ever uncertain as to whether the diagnosis is ventricular tachycardia or WPW, cardioversion is a safe and effective intervention for both rhythms. Unstable patients with either WPW or ventricular tachycardia should undergo cardioversion immediately. Other treatments for WPW in stable patients may include procainamide. Ablation may present future episodes.

Bartlett and Friedman review the pathophysiology of WPW. They discuss the congenital presence of impulse-conducting fascicles leading to this condition. They also delve into the management and recommend rhythm agents and ablation as a modality of treatment.

Figure/Illustration A is an ECG demonstrating a wide complex (red arrow) tachycardia with a delta wave (blue arrow). These ECG findings are characteristically seen in WPW syndrome.

Incorrect Answers:
Answer A: Adenosine would be indicated after vagal maneuvers in the management of supraventricular tachycardia (SVT). SVT presents as a narrow complex tachycardia without P waves. It is regular (in contrast to atrial fibrillation). Failure to respond to vagal maneuvers or adenosine warrants cardioversion. If this patient was perfusing his CNS, a trial of adenosine could be appropriate given it has a short half-life and may differentiate ventricular tachycardia from SVT with aberrancy or a bundle branch block.

Answer B: Amiodarone may be used in stable ventricular tachycardia to control the rhythm and convert it to sinus. It would not be appropriate in a hemodynamically unstable patient. It can be used in other dysrhythmias as well including atrial fibrillation and atrial flutter.

Answer D: Defibrillation is only indicated in pulseless, shockable rhythms including ventricular fibrillation (disorganized electrical activity), pulseless ventricular tachycardia (wide complex tachycardia), and pulseless torsades des pointes (twisting of the QRS complexes around an isoelectric baseline). It could cause cardiac arrest if performed on a patient with a pulse.

Answer E: Procainamide is an antidysrhythmic that can be used in tachydysrhythmias that occur in WPW. Given that this patient is unstable, it is more appropriate to perform cardioversion.

Bullet Summary:
Unstable tachyarrhythmias in the setting of Wolff Parkinson White syndrome require cardioversion.