Paroxysmal nonreentrant supraventricular tachycardia due to simultaneous fast and slow pathway conduction in dual atrioventricular node pathways

Abstract

Electrophysiologic studies were performed on a 49 year old woman who had paroxysmal nonreentrant supraventricular tachycardia due to simultaneous anterograde conduction through dual atrioventricular (AV) node pathways. Slow pathway conduction was inversely related to the preceding sinus cycle length and fast pathway conduction was determined by the Hs-A interval (measured from the His potential due to slow pathway conduction to the onset of the subsequent atrial electrogram). Major determinants of sustained simultaneous anterograde fast and slow pathway conduction during sinus rhythm were 1) a retrograde unidirectional block in both fast and slow pathways, and 2) a critical conduction delay in the slow pathway and a long enough Hs-A interval to allow sequential conduction of impulse from both pathways. Flecainide was successful in preventing recurrences of the tachycardia by eliminating slow pathway conduction during long-term follow-up.

Simultaneous Dual Fast and Slow Pathway Conduction upon Induction of Typical Atrioventricular Nodal Reentrant Tachycardia: Electrophysiologic Characteristics in a Series of Patients

“…Over the years, a few cases have been reported where simultaneous dual AV node conduction (SDNC) occurs at the induction of a typical atrioventricular nodal reentrant tachycardia (AVNRT), which has been amenable to a successful treatment by conventional slow pathway radiofrequency energy (RF) ablation 2–6 . Moreover, in some other rare cases, SDNC has been observed during normal sinus rhythm at a critical rate: if sustained, it causes a peculiar form of arrhythmia called non‐reentrant junctional tachycardia (NRJT) 7–19 …”

Nonreentrant Supraventricular Tachycardia Misdiagnosed as Inappropriate Sinus Tachycardia

“…The supportive literature describes this finding as a rare and poorly recognized cause of paroxysmal SVT that is typically resistant to pharmacologic therapy. This finding has been described in isolation and in the form of sustained tachycardia, which has been commonly classified as a nonreentrant SVT 2–6 or dual nodal response tachycardia 7…”

Profound Hypotension Due to Slow Atrioventricular Nodal Pathway Conduction during Atrial Tachycardia

“…Up to 39% of such patients with dual AV nodal physiology have no history of AV nodal reentrant tachycardia (AVNRT) 1 . Non‐reentrant supraventricular tachycardia (SVT) due to simultaneous fast and slow AV nodal pathway conduction has also been observed 2,3 . We report a case of atrial tachycardia with AV conduction alternating over fast and slow AV nodal pathways.…”