RADIOFREQUENCY CATHETER ABLATION OF VENTRICULAR ARRHYTHMIAS IN PEDIATRIC PATIENTS: ASSESSMENT OF EFFECTIVENESS AND RISK FACTORS OF RECURRENCE

To assess effectiveness of radiofrequency ablation (RFA) of idiopathic ventricular arrhythmias (VA) in pediatric subjects and risk factors of their recurrence, 259 children aged 13.4±3.1 years (5 17 years, 153 boys) with idiopathic VA were examined and surgically treated. Patients with cryocatheter ablation of arrhythmic foci were not included into the study. The study assessment included anthropometry, blood and urine lab tests, electrocardiography, Doppler echocardiography, Holter ECG monitoring, stress-test (treadmill-test) according to the modified Bruce protocol for children. The invasive electrophysiological study was performed under general anesthesia (91%) according to the commonly accepted technique which included stimulation and activation mapping. In a majority of cases (82%), the electroanatomic mapping using the CARTO navigation system (Biosense Webster, USA) was carried out. The primary indications to radiofrequency ablation of arrhythmogenic foci were presence of signs of arrhythmogenic myocardial dysfunction and symptomatic VA. Patients with frequent single and coupled ventricular premature contractions (VPC) predominated in the structure of VA (187 children; 72%). In 49% of these cases (127 children), allorhythmia was documented. In 26% of cases (67 children), VPC were associated with bursts of monomorphic ventricular tachycardia (VT). Paroxysmal VT occurred in 5 children (2%). Signs of arrhythmogenic myocardial dysfunctions (left ventricular dilatation and/or depressed ejection fraction at the background of the sinus rhythm) were found in 59% of patients (153 pediatric subjects). The most widespread location of VA foci was the right ventricle outflow tract (RV OT). The second widespread arrhythmogenic areas were the aortic sinuses and the RV inflow area, which were revealed 3 times less than RV OT. Rare locations of arrhythmogenic foci in pediatric patients were the left ventricle inflow tract, apical part of inter-ventricular septum, left ventricular outflow tract, sub-valvular space, which took place in 0.4-1% of subjects. In a majority of cases (98%), the focal type of arrhythmia took place. The highest effectiveness of RFA of 96.1 100% was observed in fascicular VT and VT originating from aortic sinus, whereas a lower effectiveness, in case of VA from RV OT and from the RV free wall (88.9% and 70.2%), respectively. The extremely low effectiveness was typical for ectopies in the apical of the inter-ventricular septum. The intra operational effectiveness after the primary RFA procedure was 86.5%. During the subsequent follow-up, a delayed or partial effect of RFA was noted in 7 patients (2.7%) and 6 patients (2.3%), respectively. In 7 children (2.7%), a repetitive intervention was performed, which turned out to be effective in 3 patients (1.2%). Other pediatric patients (n=21) did not undergo repetitive RFA. The recurrence after the primary RFA were found in 8.5% of cases (n=22), including 20 cases in the early post-operation period (91%) and 2 patients in the late post-operation period (9%). In 10 children (3.9%), a repetitive ablation was performed, which was effective in 8 cases (3.1%). Thus, RFA of arrhythmogenic focus is an effective and safe method of the VA treatment in pediatric patients. The total effectiveness of RFA in VA is 85% (100% through 70%) depending of the ectopic focus location.

idiopathic ventricular arrhythmias, ventricular premature contractions, ventricular tachycardia, fascicular tachycardia, radiofrequency catheter ablation, recurrence

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