Para-Hisian pacing. A new method for differentiating retrograde conduction over an accessory AV pathway from...

Area of Science:

• Electrophysiology
• Cardiac Pacing

Background:

• Differentiating ventriculoatrial (VA) conduction via accessory pathways (APs) and the atrioventricular node (AVN) is challenging, particularly with septal APs.
• Accurate differentiation is crucial for diagnosing and managing cardiac arrhythmias.

Purpose of the Study:

• To evaluate the efficacy of a novel para-Hisian pacing technique in distinguishing between accessory pathway (AP) and atrioventricular node (AVN) mediated ventriculoatrial (VA) conduction.
• To assess the accuracy of para-Hisian pacing in various accessory pathway locations, including septal and free wall pathways.

Main Methods:

• Para-Hisian pacing was performed in patients with and without accessory pathways experiencing AV nodal reentrant tachycardia (AVNRT).
• Ventricular pacing adjacent to the His bundle (HB-RB) was initiated at high output and then decreased to differentiate between HB-RB capture and non-capture.
• Changes in timing and sequence of retrograde atrial activation were analyzed based on pacing output.

Main Results:

• Para-Hisian pacing correctly identified retrograde AP conduction in 132 of 147 AP patients, including all septal and right free wall APs.
• Exclusive retrograde AVN conduction was indicated by an increased stimulus-atrial (S-A) interval without change in His bundle-atrial interval.
• A change in atrial activation sequence suggested the presence of both retrograde AP and AVN conduction.

Conclusions:

• Para-Hisian pacing is a reliable method for identifying retrograde conduction over septal and right free wall accessory pathways.
• Atrioventricular node conduction can mask accessory pathways located distally or those with prolonged retrograde conduction times.