Contribution of atrioventricular node inputs on orthodromic atrioventricular reentrant tachycardia cycle length

Abstract

We describe a 21-year-old woman with a previous history of orthodromic AVRT and overt preexcitation. Electrophysiological study revealed the presence of a left-sided accessory pathway. During an orthodromic AVRT a spontaneous sudden change in heart rate (141 to 202 beats/min) without any change of the QRS morphology was noted due to a decrease in AH interval (from AH = 227 ms to AH = 100 ms). We explained this phenomenon as the sudden change of the inferior inputs to superior in the AV node.