Patient 1
Patient 1 has been introduced detailly in a former publishment written
by some of our authors [2]. He was a 25-year-old
man who was otherwise healthy. His tachycardia could be induced by
ventricular burst pacing, with a complete right bundle branch block
(CRBBB) pattern, cycle length (CL) variating from 220 to 300 ms. But
S1S2 and S1S2S3 stimulation of the atrium and the ventricle did not
induce any abnormal phenomena. There were 3 types of VA relationships
during tachycardia. One was V-A 1:1 relationship with long RP intervals,
another was VA dissociation with V faster than A rate, the
3rd was VA dissociation with atrial fibrillation
(Figure 1A). Thus atrial tachycardia and atrio-ventricular reentrant
tachycardia (AVRT) could be excluded. HV intervals during sinus rhythm
and tachycardia were equal (50ms) which excluded ventricular
tachycardia. His bundle refractory period ventricular stimuli could
reset the tachycardia with H-H interval reseted earlier than the V-V
interval and terminate the tachycardia repeatedly which suggested the
existence of an AP. His bundle refractory period ventricular stimuli
during tachycardia complicated with AF suggested that the AP was not
connected to the atrium, but to the AV node (Figure 1B). Multiple QRS
fusion morphologies during His bundle refractory period ventricular
stimuli on a fixed RVA site could be observed, suggesting the AP was a
nodo-ventricular (NV) fiber which provides a broader period for His
bundle refractory period ventricular stimuli to enter the circuit more
easily (Figure 1B) [9 ]. S1S1 pacing of
RVA led to dissociation of H and V, which excluded the ventricle from
the reentrant circuit and further suggested that it were an AVNRT
(Figure 1C). Both evidences confirmed that it was an AVNRT with a
concealed NV fiber as a bystander. Sketch maps of the tachycardia are
shown in our previous work (Figure 1D) [2].
After thermo-controlled ablation (55°C, 40 watt, 90 seconds) of the slow
pathway of AV node at the lower 1/3 of the triangle of Koch, the
tachycardia could not be induced anymore.