Electrical Alternans at 300/min

Report:

Supraventricular tachycardia 300/min

Electrical alternans

Comment:

At fast rates, electrical alternans has no connotation of cardiac failure. It can be quite transient: below (Fig 73a) is a trace at only slightly slower rate, without alternans.

The rhythm, in an adult, would almost certainly be flutter with 1:1 conduction. At two weeks, the likely diagnosis is an orthodromic atrio-ventricular reentrant tachycardia. Sustained tachycardia causes heart failure in infants as well as adults – the so-called tachycardiomyopathy.

Further on (Fig 73b) is the patient in sinus rhythm. He was cardioverted with digoxin and adenosine.

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