Panel A Patient with antidromic atrio-ventricular re-entrant tachycardia (AVRT) and two previous failed catheter ablation procedures. The successful ablation site 5with 3D electroanatomical mapping) was between 10 and 11 o’clock of the tricuspid annulus. On the first beat during tachycardia, the His activation is from distal to proximal (dashed arrow) with a short HV interval, probing an antidromic mechanism. On the second beat, a spontaneous atrial premature activation interrupts the tachycardia (black triangle). On the third beat during sinus rhythm, there is evidence of reversal of the His activation to proximal to distal (dashed arrow) activation with a normal HV interval.
Panel B 3D electro-anatomical and activation map reconstruction of the right atrium and tricuspid valve during antidromic atrio-ventricular re-entrant in the same patient. The yellow dots show the areas where His potentials were recorded; the green dot demonstrates the area of the Mahaim potential, which was also the site of the successful ablation (red dots).
Figure 6. Surface ECG (electrocardiogram) and intracardiac EGMs (electrograms) in a young patient with a Mahaim accessory pathways during the repeated ablation procedure.