RESUMO
We studied the clinical features and factors of successful catheter ablation for common and uncommon atrioventricular nodal reentrant tachycardia(AVNRT). The study population consisted of 41 consecutive patients, 33 with common type AVNRT (16 males mean age of 57.8 years), and 8 patients with uncommon type AVNRT (4 males, mean age of 57.1 years). In all patients with common type AVNRT, the earliest atrial activation during tachycardia was recorded at the His bundle region. The effective ablation sites were located in the medial septal area and all cases were successfully ablated without complication. In patients with uncommon type AVNRT, dual pathway was observed in 5 patients(63%) and triple pathway in 3 patients(38%). The earliest atrial activation during tachycardias was recorded at the ostium of the coronary sinus. Radiofrequency ablation therapy was performed during sinus rhythm in 5 patients, and during tachycardia in 3 others. The effective ablation sites were located at the posterior septal area around the coronary sinus ostium. All cases were successfully ablated without any major complication, but one case had second-grade atrioventricular block after ablation. There were no significant differences between the common and uncommon type AVNRT cases with regard to the therapeutic success rate, the mean application number or the total energy applied. However, the successful ablation sites were different between the two groups. We concluded that radiofrequency catheter ablation would be effective in patients with both common and uncommon types AVNRT. Selective ablation at the site of the retrograde slow pathway exit was the most important factor for successful catheter ablation for uncommon type AVNRT. However, it should be performed only after careful analysis, taking into account the complex mechanism of uncommon type AVNRT.
