New catheter techniques for analysis of the sequence of retrograde atrial activation in man

Surgical interruption of accessory pathways underlying the preexcitation syndrome is a useful and feasible therapeutic modality in selected patients with life-threatening arrhythmias or recurrent arrhythmias refractory to conventional therapies. The sequence of retrograde atrial activation has been found to be a useful indicator of the site of the accessory pathway. The introduction of catheter electrode recordings has greatly enhanced our understanding of impulse formation and conduction in the atria. While mapping of the left atrial activation has been facilitated by recordings from the coronary sinus, exploration of the circumference of the tricuspid valve has been limited by difficulty in accurate positioning of electrode catheters in stable, reproducible positions within the right atrium, particularly the atrial septum. A new catheter technique was therefore devised to allow more accurate mapping of the endocardial surface of the right atrium. This communication describes the sequence of retrograde atrial activation during ventricular pacing in normal patients, patients with enhanced conduction of the AV node, and during reciprocating tachycardia due to reentry in the AV node, using this technique.