Atrioventricular nodal reentrant tachycardia and the dilemma of reentry circuit components: A proof of concept

Figures

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  Figure 1. Upper common pathway (UCP) Wenckebach phenomenon during atrioventricular nodal reentrant tachycardia. A: Wenckebach cycle to the atria at UCP. Surface electrocardiography shows a progressive increase in RP interval (black arrows) until a P wave blocks in the UCP. B: Wenckebach cycle illustration in UCP: green arrows indicate conduction by the fast pathway and red irregular arrows conduction by the slow pathway. Straight black arrows represent depolarization of UCP and wavy lines represent impulse block. AVN = atrioventricular node; HB = His bundle; LCP = lower common pathway.

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  Figure 2. Upper common pathway 2:1 block during atrioventricular nodal reentrant tachycardia. A: After an increase in tachycardia cycle length, the impulse blocks in the upper common pathway (UCP) every other cycle (fixed AH interval, septal VA interval, and HA interval) in a 2:1 VA fashion. B: Upper-axis P waves in frontal plane every other QRS complex corresponding to a 2:1 VA block in the UCP. Green and red arrows: conduction by the fast and slow pathways, respectively. Straight black arrows represent the impulse through the UCP and the wavy lines the impulse block. AVN = atrioventricular node; HB = His bundle; LCP = lower common pathway.

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  Figure 3. Atypical atrioventricular nodal reentrant tachycardia alternating atrioventricular and ventriculoatrial block. A: An alternating infra-Hisian and upper common pathway (UCP) block at each every other cycle is shown. B: Green and red arrows represent fast and slow pathway activation, respectively. AVN = atrioventricular node; HB = His bundle; LCP = lower common pathway.

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  Supplemental Figure 1S. Catheter positioning. Through the right femoral vein, quadripolar catheters were positioned in high atrium/ ventricle apex and His bundle. A decapolar catheter was positioned in the coronary sinus floor (proximal dipole at coronary sinus ostium) through the right internal jugular vein.

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  Supplemental Figure 2S. Supraventricular tachycardia (SVT) induction (A) Programmed high atrial stimulation with a nodal jump and, after 10ms extra-stimulus decrement (B). A supraventricular tachycardia was initiated with a spontaneous timely PAC (noted by HRA timing inconsistent with a true echo beat) just after S2 (B). A progressive increase in HA interval (HAi) along with AH interval (AHi) shortening is observed until ventriculoatrial conduction block resembling a Wenckebach phenomenon in the upper common pathway (UCP). As the UCP is not supposed to make part of the AVNRT circuit, but is interposed between the latter and the atria, a progressive decrement conduction makes the atria depolarize later (increasing the HAi and VAi). Simultaneously, a wave front leaves the circuit and depolarizes His bundle. As atria are depolarized later without delaying the progression of the impulse to His, the more HAi increases, the more AHi shortens until the impulse blocks in the UCP. Maintenance of atrial activation sequence during Wenckebach cycle suggests that atrial septum is not part circuit. PAC=premature atrial contraction; HISp=His proximal;; AVNRT=atrioventricular nodal reentrant tachycardia; VAi=VA…

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  Supplemental Figure 3S. Retrograde Wenckebach cycle in UCP during tachycardia Surface ECG showing a retrograde P wave ventriculoatrial Wenckebach cycle (black straight arrows).

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  Supplemental Figure 4S. Spontaneous atrial contraction resetting tachycardia A 2:1 VA conduction with a quite stable H-ASCp (105ms) during VA conduction is followed by a VA Wenckebach conduction (with the shortest H -ASCp of 105ms). A spontaneous atrial contraction 312ms after VA block and 12ms after His depolarization, anticipates atrium septum (HISp) 30ms, penetrates in slow pathway while the impulse was still travelling through the fast pathway (cycle 1) and anticipates the next tachycardia beat (cycle 2), suggesting diagnosis of AVNRT.

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  Supplemental Figure 5S. Surface ECG of a 2:1 VA block Upper axis P waves (black arrows) in frontal plane every other QRS complex corresponding to a 2:1 VA block in the upper common pathway.

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  Supplemental Figure 6S. AVNRT cycle length acceleration Every other alternating infra-hissian cycle and upper common pathway (UCP) blocks are followed by a 1:1 AV conduction with a left bundle branch aberrancy together with 2:1 VA conduction due to supra-circuit block (UCP).

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  Supplemental Figure 7S. Possible simultaneous exit block to the atria and ventricles in atypical AVNRT After atrioventricular nodal reentrant tachycardia (AVNRT) induction, an H (∗) signal (HB catheter), but neither atrial nor ventricular electrograms were recorded, suggesting an AVNRT concealed circuit. We hypothesize that the impulse blocked both to the atrium at the level of upper common pathway and to the ventricle at the level of or below His bundle. The third wide QRS complex is a premature ventricular contraction and does not disturb tachycardia circuit. H=His; HB=His bundle; UCP=upper common pathway; LCP= lower common pathway.

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  Supplemental Figure 8S. A second atypical Atrioventricular Nodal Reentrant Tachycardia (A) A second slow-slow atrioventricular nodal reentrant tachycardia (AVNRT) (probably the same tachycardia showed before with orthodromic and antidromic limbs inversion) was induced with a 1:2 AV conduction due to UCP block. (B). A RPi>PRi, infero-septal atrium (ABL catheter positioned in infero-septal region, anterior aspect of coronary sinus ostium) activation 35ms before supero-septal atrium (His bundle catheter) and preceding the P wave inscription suggests atypical AVNRT. AV=atrioventricular; UCP=upper common pathway; RPi=RP interval; PRi=PR interval; ABL=ablation).