EFFECTS OF ADENOSINE-TRIPHOSPHATE ON VENTRICULOATRIAL CONDUCTION - USEFULNESS AND PROBLEMS IN ASSESSMENT OF CATHETER ABLATION OF ACCESSORY PATHWAYS

The effects of adenosine triphosphate (ATP) on ventriculoatrial (VA) c onduction were examined before and after accessory pathway (AP) ablati on, with emphasis on assessment of the complication of dual atrioventr icular (AV) node pathway. By evaluating the differences in the respons e to ATP of APs and other pathways, we assessed the usefulness and pro blems of this method. Of 59 patients who underwent AP ablation, 31 sho wed pre-excitation and 28 had concealed APs. A dual AV node pathway wa s found in 9 patients (15.3%) before ablation. After ablation, a dual AV node pathway was newly found in 9 patients. Thus, the total number of patients with a dual AV node pathway was 18 (30.5%). VA conduction over APs was not blocked in 26 of 29 patients, but the remaining 3 APs were blocked transiently by ATP. ATP caused VA block over the AV node in 15 of 16 patients and a dual AV node pathway in all 11 patients. I n contrast, VA conduction over the retrograde fast pathway was blocked in 9 of 14 patients with AV node re-entrant tachycardia. ATP has litt le effect on APs, so observation of the response to ATP provides a mor e reliable and useful means of evaluating successful ablation. With th is method, however, it is important to consider the possibility of the presence of ATP-sensitive APs and ATP-resistant retrograde fast pathw ays. The influence of ablation-induced injury has not been fully clari fied. It is therefore essential to take into account various data, inc luding the comparison between data obtained before and after ablation.