Legends to figures
Figure 1 : Upper : induction of the reciprocating tachycardia by ventricular extra-stimulus with decremental retrograde conduction and a VAV pattern. Lower entrainment of the reciprocating tachycardia by fast ventricular pacing with a VAV pattern after the last ventricular paced beat (S= pacing artifact, CS and His = coronary sinus and His bundle electrodes, A=atrial electrogram, H=His electrogram).
Figure 2 : Upper : ventricular extra-stimulus delivered at the time the His bundle is refractory advanced the next atrial depolarization. Retrograde conduction through the accessory pathway has decremental properties, since although atrial event is advanced, VA interval was larger for shorter coupling interval of the premature beat. Lower : recording by the ablation catheter at the lateral tricuspid annulus : there is a specific potential between the ventricular (V) and atrial (A) electrograms during the tachycardia, similar to a His bundle potential
Figure 3 : high density 3D mapping of the right lateral part of the heart during the tachycardia, showing first the ventricular activation (blue) preceding the area of activation of the specific potential (violet) and then the atrial activation (red and yellow) with a concentric propagation from the preceding area. Besides are shown the potentials which were recorded by the system at each site (white = ECG and atrial reference, red = local bipolar electrogram, yellow = local unipolar electrograms, green = « trend » in local activation as a summation of local electrograms). Of note that there was an additional component between the ventricular and atrial components on the trend. White dots represent the expected location of the tricuspid annulus, and black dots the approximate location of the additional structure responsible for the specific potential on the vestibular part of the valve, and which could be considered as an accessory AV conduction system/network.