Radiofrequency catheter ablation of posteroseptal accessory pathways--results of a step-by-step ablation approach

Electrocardiographic estimation of successful ablation site in patients with manifest inferior paraseptal accessory pathway

Inferior paraseptal accessory pathways (APs) have a wide distribution and prediction of AP location before radiofrequency ablation is very important in such pathways. We aimed to estimate successful ablation site based on electrocardiogram in 137 patients (mean age: 25.8±9.0; 126 males) with single manifest inferior paraseptal AP. Right endocardial inferior paraseptal APs were discriminated from left endocardial APs with an R/S ratio <1 (p<0.001) and negative delta wave in lead V1 (p<0.001). Epicardial inferior paraseptal APs were differentiated from endocardial APs by a negative delta wave in lead II (p=0.001), positive delta waves in AVR (p<0.001) and V1 (p=0.012), R/S ratio <1 in lead II (p=0.03), and R/S ratio ≥1 in V1 (p=0.04). Delta wave polarity and R/S ratio in lead V1 differentiate right endocardial inferior paraseptal APs from left endocardial APs. Delta wave polarities in leads II, AVR and V1, and R/S ratios in leads II and V1 estimate epicardial inferior paraseptal APs.

Ablation of posteroseptal and left posterior accessory pathways guided by left atrium-coronary sinus musculature activation sequence

INTRODUCTION

While some posteroseptal and left posterior accessory pathways (APs) can be ablated on the tricuspid annulus or within the coronary venous system, others require a left-sided approach. "Fragmented" or double potentials are frequently recorded in the coronary sinus (CS), with a smaller, blunt component from left atrial (LA) myocardium, and a larger, sharp signal from the CS musculature.

METHODS AND RESULTS

Forty patients with posteroseptal or left posterior AP were included. The LA-CS activation sequence was determined at the earliest site during retrograde AP conduction. Eleven APs (27.5%) were ablated on the tricuspid annulus (right endocardial), 9 (22.5%) inside the coronary venous system (epicardial), and 20 (50%) on the mitral annulus (left endocardial). A "fragmented" or double "atrial" potential was recorded in all patients inside the CS at the earliest site during retrograde AP conduction. Sharp potential from the CS preceded the LA blunt component (sharp/blunt sequence) in all patients with an epicardial AP, and in 10 of 11 (91%) patients with a right endocardial AP. Therefore, 18 of 19 (95%) APs ablated by a right-sided approach produced this pattern. The reverse sequence (blunt/sharp) was recorded in 19 of 20 (95%) patients with a left endocardial AP.

CONCLUSION

During retrograde AP conduction, the sequence of LA-CS musculature activation-as deduced from analysis of electrograms recorded at the earliest site inside the CS-can differentiate posteroseptal and left posterior APs that require left heart catheterization from those that can be eliminated by a totally venous approach.