br Discussion There were recurrences out of patients

Discussion There were 2 recurrences (8.3%¸ 2 out of 24 patients), 1 of which occurred immediately following the procedure. In this patient, SVT was not induced with programmed atrial or ventricular stimulations after the ablation of accessory pathway. Ventriculoatrial conduction was through the AV node upon ventricular stimulation. However, the patient developed SVT the next day and was treated with propafenone. The other patient had late recurrence of a manifest accessory pathway, which was asymptomatic for a long time. The SVT, which was atrial ectopic tachycardia, was probably induced with the use of a neurostimulant having potential chronotropic and proarrhythmic side effects. Our acute success rate and recurrence rate are comparable to other studies [2–5]. Lesh et al. [3] reported 85% successful elimination and 2.24% recurrence rate of left-sided accessory pathways. Calkins et al. [6] had an 87% success rate with a retrograde approach. The retrograde aortic approach has the potential for complications related to arterial access and manipulation of a stiff catheter across the aortic valve [7,8]. In certain cases, close proximity of the RF catheter to the coronary order leptomycin b or the mitral valve may cause injury at these sites. However, it is a simpler and less time consuming approach in terms of access. Alternatively, the transseptal approach needs special training and has potential procedural risks including pericardial effusion and cardiac tamponade. A learning curve is associated with this technique and is inversely related to the complication rate. Katritsis et al. [9] documented 1.27% cardiac tamponade among 393 patients with the use of the transseptal access. In a study by von Alvensleben et al. [10], the incidence of pericardial effusion was 1.9% among pediatric patients undergoing transseptal ablation. Tang et al. [11] described ST-T wave elevation during 0.38% of the transseptal ablation procedures. We do not favor transseptal approach for pediatric patients in our institution mainly because of the lack of special skill in performing this technique in children. Lesh et al. [3] reported a 6.7% complication rate during the retrograde approach, most of which were attributable to arterial access. The most serious complication was the dissection of the left main coronary artery in 1 patient. In this procedure, the ablation catheter tip had lodged briefly in the left coronary artery during an attempt to cross the aortic valve. Lesh et al. [3] found no difference in the incidence and severity of complications when they compared the retrograde and transseptal approaches. The success rate and total procedure and fluoroscopy times were similar. In our study group, no major complications were observed; only 1 patient had groin hematoma, which recovered without any consequences. The overall minor complication rate was 12% (3 patients out of 25). Mean procedure and fluoroscopy times were shorter in our study, compared to those in the study of Lesh et al. (procedure time 71.54±21.05min, fluoroscopy time 31.42.60±19.57min in our study vs. 220±12.8min and 44.1±4.4min, in the study of Lesh et al.). Nevertheless, the patient with an unsuccessful procedure had very long fluoroscopy time of 86min. Expectantly, 3-dimensional electroanatomic mapping may eliminate or reduce fluoroscopy duration in such difficult cases while performing safe and effective accessory pathway ablations. Injury to valvular structures has occasionally been described related to left-sided ablations. The frequency of lesions has been as high as 12% for the mitral valve and 30% for the aortic valve [7]. The aortic valve may be injured either directly by the catheter tip when it is passed through the valve or by compression and stretching of the cusps by the catheter shaft during prolonged placement in the ventricle. Olsson et al. [15] studied the frequency of valvular insufficiency after the long-term follow-up of retrograde aortic RF catheter ablation procedures. They demonstrated the incidence of valvular damage as 1.9% among 179 patients (mitral regurgitation: 2 patients; aortic regurgitation: 2 patients). Injuries are likely to be related to the duration of the procedure and number of energy applications and passes through the aortic valve.