Comparison of Properties of Slow Pathway Potential between Successful and Unsuccessful Radiofrequency Applications in Patients who Underwent Catheter Ablation for Atrioventricular Nodal Reentrant Tachycardia

Findings concerning selective slow pathway radiofrequency ablation for atrioventricular nodal reentrant tachycardia (A VNRT) using the slow pathway potential (SPP) guided method are reported. The electrogram at the SPP recording site showed double potentials consisting of the atrial potential (A) and SPP. However, SPP is usually recorded widely in the right atrial posteroseptal region. To examine whether there was any characteristic marker in the electrogram at the SPP recording site specific to successful RF application, the properties of SPP and its anatomical locations in both successful (S) (38 sites) and unsuccessful (UN) (28 sites) application sites were analyzed in 38 patients who underwent SPP-guided ablation. The distance between the upper margin of the coronary sinus ostium (UCSO) and the ablation catheter (ABL) (DUCSO-ABL) was shorter in S than in UN (2.3 ± 6.3 mm vs. 9.0 ± 5.2 mm below the level of UCSO, p < 0.001). The interval between A and SPP (A-SPP) was longer in S than in UN (44.2 ± 9.9 msec vs. 24.0 ± 7.0 msec, p < 0.001). RF applications at the more anterior sites with longer A-SPP were more successful than at other sites. The sensitivity and specificity of A-SPP (more than 40 msec) were superior to those of DUCSO-ABL (within 5 mm) as the marker for the successful application (sensitivity; 73.7% v.s. 68.4%, specificity; 100% v.s. 82.1 %, respectively). In conclusion, the sites with longer A-SPP might be specific for successful ablation

Structural Characteristics of Koch's Triangle in Patients with Atrioventricular Node Reentrant Tachycardia

The aim of this study is to investigate whether patients with atrioventricular node reentrant tachycardia (AVNRT) present different structural characteristics of Koch's triangle from patients with atrioventricular (AV) reentrant tachycardia and other control patients. Fifty-eight patients with arrhythmia or chest pain underwent selective coronary sinus angiography so that the diameter of the coronary sinus could be measured. The patients with arrhythmia also underwent electrophysiological study and measurement of the height of Koch's triangle. Patients with AVNRT had large coronary sinus ostial diameters compared with patients with AV reentrant tachycardia and those with chest pain (13.6 ± 2.2 mm vs. 10.6 ± 2. 7 mm [p < 0.005] and 10.0 ± 2.1 mm [p < 0.002], respectively), while there were no differences in distal diameter. The ostial diameter in patients with dual AV node pathways but noninducible AVNRT (11.8 ± 1.5 mm) tended to be smaller than that in patients with AVNRT. No differences in the height of Koch's triangle and electrophysiological characteristics, including AV node properties, were found among the study groups. In conclusion, an increased size of the coronary sinus ostium (the base of Koch's triangle) is a structural characteristic in patients with AVNRT and may be the substrate needed for the appearance of AVNRT