Radiofrequency catheter ablation (RFCA) has become the most effective and safe method for treating Wolff-Parkinson-White (WPW) syndrome in children and adolescents. Accessory pathways (APs) located in the postero-septal region account for up to 28% of all these APs. Despite the fact that children are smaller than adults, leading to smaller coronary arteries and shorter distances between these vases and posterior septum, and also the growth aspect of these small coronary arteries, coronary artery injury is rarely reported.3,4 Furthermore, long-term consequences of radiofrequency lesions in developing myocardium are not completely known. Angiographic follow-up studies, limited up to 6 months after ablation, have shown no evidence of coronary abnormalities, but few cases of procedure-related late deaths have been reported. We describe a case of right coronary artery (RCA) injury secondary to RFCA of a postero-septal accessory pathway in a child, successfully treated with mechanical reperfusion and present the follow-up angiography at 1 year.

Case Report
A 12-year-old girl with WPW syndrome was referred to São Paulo Hospital at Federal University of São Paulo, Brazil, for RFCA. Clinical evaluation was unremarkable and baseline surface electrocardiogram (ECG) showed sinus rhythm with short PR interval and pre-excitation with a negative delta wave in leads D2, D3, avF and V1, suggesting a right postero-septal accessory pathway.

Figure 1

Twelve-lead electrocardiogram showing ST elevation in the inferior leads and ST depression in leads V1-V4 after radiofrequency current delivered in the postero-septal region.

The procedure was undertaken under general anesthesia. Bipolar electrograms were filtered through a range of 30–500 Hz and recorded on a multichannel polygraph (BARD Electrophysiology, Billerica, Massachusetts). An electrophysiologic (EP) study was performed using a standard electrode catheter in the high right atrium, His bundle, coronary sinus and right ventricular apex, and confirmed the accessory pathway in the right postero-septal region. A 7.0 French (Fr) quadripolar thermistor catheter with a 4 mm tip electrode (EP Technologies, Inc., Sunnyvale, California) was used for endocardial mapping and radiofrequency current delivery in the coronary sinus ostium, eliminating the APs transiently. No impedance rise was observed. After 5 applications of RF energy (60 seconds), ECG showed acute ST elevation in the inferior leads and ST depression in leads V1 to V4 (Figure 1), without change in the hemodynamic status.

Coronary angiography revealed total occlusion of the distal RCA (Figure 2A), which was resistant to intracoronary nitroglycerine (100 µg). A 0.014´´ angioplasty crosswire was then manipulated across the obstruction, resulting in recanalization of the small posterior descending artery (1 mm diameter) with TIMI III flow (Figure 2B) and immediate complete ST segment resolution. There was a small increase in CPK-MB (78 units, reference value = 24). The echocardiogram was normal and the patient was discharged on amiodarone because of recurrence of pre-excitation.

At the 1-year follow-up examination, a new coronary angiography depicted normal circulation through the posterior descending artery and total occlusion of the ventricular posterior artery, which was filled through collateral circulation from the RCA marginal branch (Figure 3). Left ventriculography was normal.

Discussion

Figure 2

(A) Left anterior oblique view demonstrating total occlusion of the distal right coronary artery. Ablation catheter was located in the coronary sinus ostium. (B) Left anterior oblique view demonstrating recanalization of the posterior descending artery with angioplasty guidewire.

Radiofrequency catheter ablation has been largely applied for treatment of accessory pathways in the pediatric population with a high success rate and low risks. In fact, except for children with congenital heart disease and the smallest children, complications of RFCA in this population have been reported to be similar to those in adults.¹ Coronary artery damage is rare, but potential complications secondary to RF ablation, which include coronary artery spasm, acute damage and thrombosis and chronic occlusion due to progressive scarring, and local chronic dissection.

Few cases have been reported of acute and chronic complications following RF current application in both the right and left sides. As in this report, Khanal et al.⁵ described a case of RCA occlusion post RFCA in a child who was treated with stenting. Other authors reporting on ischemic complications following RF ablation found that coronary angiography was normal,^7,8 suggesting that those particular cases were a consequence of reversible spasm.

In our patient, coronary angiography was immediately performed; it showed distal RCA occlusion, which was treated with mechanical angioplasty through a guidewire with reperfusion of a posterior descending artery. However, reperfusion of the posterolateral branch was not achieved. Because of immediate resolution of ECG changes, the diameters and the bifurcation of these arteries, and finally, the unknown results of angioplasty or stenting in these small and growing arteries, we opted for a more conservative approach, trying to keep flow and resolution of ST segment changes. The patient had an uneventful follow-up, with no left ventricular dysfunction or additional stenosis; she developed a rich collateral circulation. Also, no other ventricular arrhythmias were observed during follow-up.

Figure 3

1-year follow-up angiogram reveals normal circulation through posterior descending artery and total occlusion of ventricular posterior artery. Collateral circulation from the RCA marginal branch is observed.

We performed coronary angiography one year later; it showed no additional coronary artery abnormalities. This was an important concern because there are limited data regarding the long-term effects of thermal damage to the coronary arteries. In a recent study on growing animals, Bökenkamp et al. demonstrated that RCA stenosis occurred as a complication of RF application mainly when RF current was applied to the right atrium side.⁹ These authors reported that although coronary angiography did not show coronary artery abnormalities, pathologic examination of the RCA showed intimal thickening and vessel obstruction.

Conclusion
Accessory pathways and coronary arteries run over the atrioventricular groove. Perhaps the proximity of the distal RCA (especially in bifurcation of the posterior descending artery and the postero-lateral branch) with the postero-septal pathways is the most important anatomic relationship for coronary injury risk during electrophysiologic interventions for catheter ablation of accessory pathways. Thus, coronary artery occlusion can be a risk during RF catheter ablation. In this situation, blood flow restoration must be achieved. Coronary artery size and bifurcation in this area may be a potential limitation for angioplasty and stenting in the pediatric population. Although coronary artery occlusion during RFCA has been previously described, we believe this case is unique because it reports the mechanical reperfusion with crosswire as a reasonable method to restore blood flow and shows the resultant long-term angiographic follow-up.

This article has been reprinted with permission from the Journal of Invasive Cardiology 2003;15:173–175