Junctional ectopic tachycardia (JET)

Patient

Young man 20 years of age with no prior history, referred to the department for palpitations;

Trace

This tracing was recorded during the sensation of palpitations; tachycardia of 140 bpm, narrow QRS with atrioventricular dissociation; QRS complexes without any particular abnormality are found with a sinus atrial activity (identifiable P wave, positive in leads I, II and negative in aVR) that is slower and dissociated from ventricular activity; these elements are indicative of a junctional ectopic tachycardia; atrial activity is normal and sinus, which allows eliminating the hypotheses of atrial fibrillation or flutter; atrial and ventricular activities are dissociated, which eliminates reentry due to an accessory pathway (mandatory 1:1 ratio between atria and ventricles); the probability of an intranodal reentry with dissociated atrial activity is very low;

Trace

Tracing recorded a few minutes later with, in this instance, a retrograde conduction to the atria (negative P waves in inferior leads) and a 1:1 ratio;

Exergue

Junctional ectopic tachycardia is usually reflected on the electrocardiogram by a narrow QRS tachycardia (rate between 160 and 300 bpm) with atrioventricular dissociation;