Catheter ablation of manifest posteroseptal accessory pathway associated with coronary sinus diverticula in a child with congenitally corrected transposition of the great arteries

Introduction

Patients with congenitally corrected transposition of the great arteries (ccTGA) usually have some specific electrophysiological features, such as twin AV node and accessory pathway (AP)-related supraventricular tachycardia (SVT) (1-3). There is limited number of AP-related case presentations of patients with both ccTGA and Wolff–Parkinson–White (WPW) syndrome (3,4).

Some of the posteroseptal pathways are related to coronary sinus (CS) diverticula, and these pathways are close to the epicardium. Therefore, multiple ablation entries can cause ablation failure (4,5). Till date, there has been no report of ccTGA accompanied with WPW syndrome treated by an ablation from inside the CS diverticula in pediatric patients. Here we present a successful radiofrequency (RF) ablation of the CS diverticula-related manifest posteroseptal AP in a pediatric patient with ccTGA.

Case Report

A 5-year-old male patient, weighing 18 kg, was referred to our clinic with multiple antiarrhythmic-resistant SVTs. He had a medical history of pulmonary banding for ccTGA, large VSD, right ventricular hypoplasia, and pulmonary hypertension. Left manifest posteroseptal AP ablation was performed two times because of medical therapy-resistant SVT, but tachycardia recurred.

He underwent catheter ablation because of SVT attacks that worsened the hemodynamics of the patient and that required cardioversion (Fig. 1). A three-dimensional (3D) mapping system (EnSite System, St. Jude Medical, Minneapolis, Minnesota, USA) and fluoroscopy were utilized during the procedure. The baseline sinus cycle length was 650 ms with an AH interval of 79 ms and a short HV interval of 10 ms. During both, V-pace was done from an RV catheter and SVT the earliest ventriculoatrial (VA) activation was between coronary (CS) catheter 7-8 and 5-6. Because the patient had previously undergone ablation in the left posteroseptal region, mapping was first done from the left side using the transseptal technique. The earliest area during SVT was again the left posteroseptal region. Ablation was initiated with a 5-Fr RF ablation catheter, and the tachycardia stopped with a VA block in the third second of the ablation (Fig. 2). After three RF lesions, the WPW syndrome pattern recurred. When we performed remapping, the earliest area was found to be the CS ostium this time, and CS diverticula were detected by CS angiogram. The region 40 ms ahead of the surface delta was labeled with mapping. Coronary angiography was performed to detect coronary arterial proximity to the target. We started RF ablation at 20 W, 50°C and AP was ablated 4 th second of the lesion. We completed the ablation with four short RF lesions Anteretro AP disappearance, confirmed by adenosine (Fig. 3). The patient has remained asymptomatic, and no pre-excitation has been observed on ECG.

Figure 1.

On the left side, WPW pattern was observed in the 12-channel ECG records of patient with ccTGA. On the right side, one of the documented orthodromic SVT attacks was observed

Figure 2.

On the top left side, a transition to the left atrium was observed by making a transseptal puncture. On the top right side, a successful RF ablation region is shown at the left posteroseptal area. On the bottom left, some successful ablation records were observed. On the bottom right, some successful RF ablation regions are labeled with orange dots at oblique and lateral positions

Figure 3.

On the top left side, CS diverticula were observed on the CS angiogram. On the top right side, the preexisting transition disappeared by means of RF ablation, which was performed from the CS diverticula. On the bottom left side, the proximity between the RF lesions (red dots) that were given inside the left CS diverticula and the RF lesions (orange dots) that were given to the left posteroseptal region (by EnSite) is remarkable. On the bottom right side, it was observed that the adenosine AP was not antegrade after the operation and VA transmission was disassociated with a concurrent V-pace at 400 ms

Discussion

RF ablation can be performed using 3D electroanatomic mapping systems for most of the complex congenital cardiac diseases. Almost 2%–5% of patients with ccTGA have one or more AP-related tachycardia substrates (2). In children, ccTGA and WPW co-occurrence is common, and the ablation experiences are limited with case presentations and low-numbered case series (3, 6, 7). In these cases, AP is usually seen in the left posteroseptal region, especially in the ones with Ebsteinoid valve (2, 6, 7). Although ablations have been performed from the retrograde aortic pathway to the tricuspid valve on the left side, the presence of the septal leaflet may increase the risk of valve disruption in the retroaortic approach (4). Therefore, it is recommended to perform ablation by passing a catheter to the left atrium using the transseptal approach in the case of left-sided APs in patients with ccTGA (2). In our clinic, ablation is performed using transseptal puncture for all left-sided APs in pediatric patients. Although transseptal puncture in patients with congenital heart diseases is difficult, it can be successfully performed by tagging of the septum (2,8).

In the present study patient, posteroseptal APs could have been related to CS diverticula, and this could have caused multi-ablation attempts and failures. The CS musculature in the diverticulum acts as the connection between the atrial and ventricular musculature and forms AP (3,7). Although these are limited in pediatric patients, it was reported that an AP ablation from CS diverticula can be successfully performed even in very small children with a normal heart (9). To the best of our knowledge, this is the first case of a pediatric patient with ccTGA accompanied with WPW syndrome treated by ablation from inside the CS diverticula.

Conclusion

AP ablation can be difficult in complex congenital heart diseases. In addition, CS diverticula should be taken into account in recurrent posteroseptal APs.