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.