Orthodromic tachycardia due to an accessory pathway (AVRT)

Patient

31-year-old patient presenting palpitations with sudden onset and termination; ECG recorded during the course of an episode;

Trace

Regular tachycardia, 180 bpm, narrow QRS; atrial activity difficult to visualize but seemingly present in the T wave with a 1:1 ratio;

Trace

Sino-carotid massage; termination of tachycardia; recovery of sinus rhythm with obvious pre-excitation (short PR + delta wave); repolarization disorders in conjunction with pre-excitation;

Trace

Electrocardiogram performed after ablation of a left posterior accessory pathway; disappearance of pre-excitation, normal PR and evidence of a physiological septal q wave in V5-V6; early repolarization;

Exergue

In orthodromic tachycardia, the impulse descends from the atrium to the ventricle through the bundle of His and ascends through the bundle of Kent; the tachycardia is regular, with sudden onset and termination, with a 1:1 A/V ratio, the P'R interval being longer than the RP' interval;