1. A 47 year old man presents to the ED with intermittent palpitations.
Although he can recall episodes occurring occasionally over
perhaps the last 6 months, they have become much more frequent
and prolonged over the past 2 days. Each time he says he can “..feel
my heart racing…” and becomes light headed, although he has not
collapsed. He denies chest pain. He is usually well and is on no
regular long-term medications.
•Describe and interpret the ECG
•What options are there for treating him ?
•What is likely the best of these options ?
2.
3. The ECG shows a transition about 6 seconds into the trace from one that shows
typical features of Wolff-Parkinson-White (WPW) syndrome to one of a regular
broad complex, but supraventricular, tachycardia.
The signs of WPW here are a short PR interval (<0.12sec) and a slurred upstroke
(known as a Delta wave) to the slightly widened QRS, and most obvious in V2 &
V3. The tachycardia is very rapid (>200bpm) regular and broad but there is clearly
a P wave before each QRS. So this will be an “antidromic” re-entrant tachycardia
where the atrial impulses are conducted to the ventricles by the accessory pathway
and not through the normal path via the AV node.
The options that are worthy of consideration are:
•“Observe” - monitor as his history suggests self-terminating episodes.
•Electrical cardioversion with cautious procedural sedation.
•Chemical cardioversion using agents that slow accessory pathway conduction but
don’t further block the AV node. The best of these is procainamide (currently
unavailable in Australia) & perhaps flecainide.
The safest option is likely observation in a monitored area with DC cardioversion if
needed (i.e. for prolonged arrhythmia or CVS collapse). Be careful to avoid AV
blockers (especially verapamil and Beta blockers).
