Typical atrio-ventricular nodal reentrant tachycardia

Patient

54-year-old patient with a long history of well-tolerated tachycardias which terminate spontaneously after 2 to 3 minutes; daily episodes of longer duration since some time;

Trace

The rhythm is initially sinus; the tachycardia begins after an atrial extrasystole conducted to the ventricle with a sudden increase in PR interval; regular tachycardia with narrow QRS complexes, identical to the complexes of sinus origin; difficulty in differentiating atrial activity (during tachycardia, changes in the pattern of the portion preceding the QRS but also slight modification of the terminal portion of the QRS compared to the sinus complexes);

Trace

Identical tachycardia;

Trace

Interruption of the tachycardia after flash injection of an Adenosine ampule; recovery of sinus rhythm with slightly prolonged PR interval; the comparison of the QRS complex in tachycardia and in sinus rhythm shows a difference in the end of the QRS-beginning of the ST segment which is clearly visible in aVR and from V1 to V4 suggesting the presence of an atrial activity appended to the QRS during the tachycardia;

Exergue

The onset of a tachycardia by typical AVNRT (slow-fast) is generally characteristic: after an atrial extrasystole, the fast pathway is blocked, the impulse is then transmitted in anterograde manner with a conduction jump and a sudden prolongation of the PR interval. Atrial pacing easily triggers this type of tachycardia as opposed to ventricular pacing, where triggering is much more difficult.