The ECG (Figure 3 shown on page 16) is from a 35-year-old male who presents with paroxysmal tachycardia.

e) What condition is demonstrated? Describe the characteristic features. (30% marks)

f) What would be the possible pharmacological options if his tachycardia were to recur?
(10% marks) 

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College answer

e)    Wolf-Parkinson-White syndrome                                 
•    short PR interval, less than 3 small squares (120 ms) 
•    slurred upstroke to the QRS indicating pre-excitation (delta wave) 
•    broad QRS 
•    secondary ST and T wave changes 
 
f)    IV procainamide or amiodarone is preferred, but any class Ia, class Ic, or class III antiarrhythmic can be used      
 

Discussion

The ECG features of WPS are:

  • The PR interval is short (less than 0.12 seconds)
  • There is a delta wave (a slurred upstroke of the QRS complex)
  • Wide QRS (because the delta wave widens it)
  • ST Segment and T wave discordant changes: T waves point in the opposite direction to the QRS.
  • Pseudo-Q waves: negatively deflected delta waves in the inferior/anterior leads
  • prominent R wave in V1-3 (mimicking posterior infarction).

Management of SVT in this condition:

  • Vagal manoeuvres
  • AVOID AV node blocking drugs such as adenosine, digoxin, beta blockers and calcium channel blockers
  • Procainamide, ibutilide or amiodarone are the only antiarrhytmics useful in WPW
  • DC synchronised cardioversion

Flecainide or propafenone are used in long term management. Amiodarone also OK - but the side effect profile in long term use is not very nice for younger patients. 

In general:

Pharmacological Peculiarities of WPW
Arrhythmia Drugs contraindicated Drugs Recommended
Orthodromic AVRT  
  • Adenosine
  • Verapamil
  • Diltiazem
  • Procainamide
  • Amiodarone
Antidromic AVRT
  • Adenosine
  • Verapamil
  • Diltiazem
  • β-blockers
  • Digoxin
  • Procainamide
  • Flecainide
  • Propafenone
  • Amiodarone
AF
  • Adenosine
  • Verapamil
  • Diltiazem
  • ß-blockers
  • Digoxin
  • Procainamide
  • Ibutilide
  • Dofelitide
  • Flecainide
  • Amiodarone

In case you were wondering, WPW patients die sudden cardiac deaths when they develop AF, which is conducted rapidly and erratically through their aberrant pathway, producing VF (Obeyeseker et al, 2012)

References

References

Wellens, Hein JJ, and Dirk Durrer. "Effect of digitalis on atrioventricular conduction and circus-movement tachycardias in patients with Wolff-Parkinson-White syndrome." Professor Hein JJ Wellens. Springer Netherlands, 2000. 63-68.

Gulamhusein, S. A. J. A. D., et al. "Acceleration of the ventricular response during atrial fibrillation in the Wolff-Parkinson-White syndrome after verapamil."Circulation 65.2 (1982): 348-354.

Munger, T. M., et al. "A population study of the natural history of Wolff-Parkinson-White syndrome in Olmsted County, Minnesota, 1953-1989."Circulation 87.3 (1993): 866-873.

Svenson, ROBERT H., et al. "Electrophysiological evaluation of the Wolff-Parkinson-White syndrome: problems in assessing antegrade and retrograde conduction over the accessory pathway." Circulation 52.4 (1975): 552-562.

Narula, Onkar S. "Wolff-Parkinson-White Syndrome A Review." Circulation 47.4 (1973): 872-887.

and, somewhat more recently...

Scheinman, Melvin M. "History of Wolff‐Parkinson‐White Syndrome." Pacing and clinical electrophysiology 28.2 (2005): 152-156.

Keating, L., F. P. Morris, and W. J. Brady. "Electrocardiographic features of Wolff-Parkinson-White syndrome." Emergency medicine journal 20.5 (2003): 491-493.

Obeyesekere, Manoj, et al. "Risk of sudden death in Wolff-Parkinson-White syndrome: how high is the risk?." (2012): 659-660.

Luigi Di Biase, M. D., Edward P. Walsh, and Bradley P. Knight. "Treatment of symptomatic arrhythmias associated with the Wolff-Parkinson-White syndrome." UpTo Date