Supraventricular Tachycardia

SVT is a ‘narrow complex’ regular tachycardia with a heart rate >180/min in children (and >220/min in infants).

The tachycardia is caused by a secondary pathway activation causing re-entry through the AV node.

In most cases, no cause is found but few children may have Wolf Parkinson White syndrome, while others are post-cardiac surgery or may have a structure heart disease.

Presentation

Children can be asymptomatic or sometimes present with intermittent palpitations, chest discomfort, dizziness or syncopes. Young children may present with irritability and reduced feeds due to reduced cardiac output.

On examination children may appear well if still hemodynamically compensated. They may present with shock with low BP and increased CRT, increased RR, or have signs of heart failure. 

ECG shows ‘narrow complex’ regular tachycardia with HR typically over 250 bpm in infants.

Those with WPW syndrome show ‘delta wave’.

Management

If haemodynamically stable, SVT requires initial stabilising of ABCDE with high flow oxygen and IV access.

Then perform vagal manoeuvers.

If sinus rhythm not achieved then give IV Adenosine.

Those who are haemodynamically unstable, require initial stabilising followed by synchronised cardioversion with lower energy at 0.5 joules/kg.