An Unusual Cause of Incessant Tachycardia

Incessant Non‐Reentrant Supraventricular Tachycardia Interrupted By Apparent Simultaneous Wenckebach Sequences along Both Nodal Pathways

“…The association between non‐reentrant supraventricular tachycardia and tachycardia‐induced cardiomyopathy has been casually reported 1,2,4,10 . This appears rather frequent due to the rarity of this arrhythmia, but this is, however, not surprising in view of the permanent fast ventricular rate present in these patients.…”

“…For such a mechanism to be possible, several electrophysiological conditions should be simultaneously met. First, the conduction time in each pathway should be long enough to exceed the refractory period of the lower common pathway and/or His bundle‐Purkinje tissue 1–4 . Second, retrograde conduction should be poor to absent in both the fast and slow pathways, 1–6 allowing successive uninterrupted anterograde conductions along both pathways and thus the perpetuation of the arrhythmia.…”

“…First, the conduction time in each pathway should be long enough to exceed the refractory period of the lower common pathway and/or His bundle‐Purkinje tissue 1–4 . Second, retrograde conduction should be poor to absent in both the fast and slow pathways, 1–6 allowing successive uninterrupted anterograde conductions along both pathways and thus the perpetuation of the arrhythmia. If double responses can occasionally induce isolated slow‐fast nodal echoes 1 or AV node reentrant tachycardia, 7 non‐reentrant supraventricular tachycardia usually occur in an incessant fashion and are only exceptionally associated with reentrant tachycardia 2,3,6,8 because of the second mandatory condition.…”

“…Second, retrograde conduction should be poor to absent in both the fast and slow pathways, 1–6 allowing successive uninterrupted anterograde conductions along both pathways and thus the perpetuation of the arrhythmia. If double responses can occasionally induce isolated slow‐fast nodal echoes 1 or AV node reentrant tachycardia, 7 non‐reentrant supraventricular tachycardia usually occur in an incessant fashion and are only exceptionally associated with reentrant tachycardia 2,3,6,8 because of the second mandatory condition. The only exceptions have been linked to the existence of more than two pathways, 3 or to the fact that block of retrograde conduction was not fixed 2,3 or resolved under isoproterenol 6,8 .…”

“…The only exceptions have been linked to the existence of more than two pathways, 3 or to the fact that block of retrograde conduction was not fixed 2,3 or resolved under isoproterenol 6,8 . Non‐reentrant supraventricular tachycardia was first reported in 1979 by G. Csapo 9 and to the best of our knowledge, only 34—mostly isolated–cases have been published so far, 1–6,8 this entity being apparently rather exceptional, even if misdiagnosed cases are likely 4,6 . The elimination of conduction along the slow pathway by RF ablation led to the definitive cure of this unusual arrhythmia in all the reported cases.…”