The Evaluation Of RS₂ In Mapping The Target Site For Slow Pathway Abltion

Objective: To investigate the value of using RS2 in mapping the target site for slow pathway ablation.Methods:40 patients with AVNRT (atrioventricular nodal reentrant tachycardia) were randomly dividied into RS2 mapping group(20 cases) and ananatomic- electrogram mapping group (20 cases).In RS2 group,as the catheter was at the Kock triangle steady,with little A-wave and big V-wav, tachycardia was initiated with HAR stimulation , then single extrastimuli (RS2) were delivered from the ablation catheter tip beginning by 20 ms less than the tachycardia cycle length and decrementing by 10 ms until tachycardia terminated or loss of capture occurred . At last, the slow pathway was ablated at the site at which AVNRT was terminated with the longest coupling interval. In anatomic-electrogram group,between His and coronary sinus ostium with LAO 45°as the atrial wave was smaller than ventricular wave (A:V<0.5) , and fragmentive, two-dimensional,steady,without His potential.The radiofrequency current was delivered.The mapping time, procedure duration,fluoroscopy time,radiofrequency ablation time were studied.The radiofrequency energy,impedance and complication such as third-degree atrial ventricular block (Ⅲ°AVB)were observed.Results:Mapping time, procedure duration,fluoroscopy time,radiofrequency ablation time were less in RS2 group than those in anatomic-electrogram group(P<0.01). Ablation Suceess rate was 100% in two groups without the complication of Ⅲ°AVB. Conclusion: RS2 mapping should be superior to anatomic-electrogram mappingin guiding ablation for slow pathway.