Cycle Length Alternation during Atrioventricular Reentrant Tachycardia: What Is the Mechanism?

An irregularly irregular supraventricular tachycardia: What is the mechanism?

“…However, in our case, atrial activation sequences were identical regardless of VA intervals. Another paper reported that cycle length alternation during orthodromic AVRT was caused by conduction delay at the left atrium‐CS musculature connection, 5 but in our case, atrial activation potentials at CS electrodes were not separated into left atrial and CS musculature potentials. Speculating on the mechanism of two retrograde conduction patterns with same atrial activation sequence but different conduction time, the following possibilities were considered; two very closely spaced APs or one AP with longitudinal dissociation.…”

“…4 However, in our case, atrial activation sequences were identical regardless of VA intervals. Another paper reported that cycle length alternation during orthodromic AVRT was caused by conduction delay at the left atrium-CS musculature connection, 5…”