Introduction: Coronary sinus (CS) diverticulae are a known cause of posteroseptal accessory pathway. These rare congenital anomalies can be diagnosed using different imaging modalities including coronary sinus angiography and transoesophageal echocardiography. Atrial fibrillation in the presence of an accessory pathway can be fatal though accessory pathway ablation provides a high success rate of cure.
Case: A previously healthy 9-year-old boy was transferred to our paediatric cardiology centre following a sudden cardiac death event related to pre-excited atrial fibrillation.
He collapsed while playing football and was unresponsive. When the ambulance team arrived at the scene, he was noted to be in a very irregular broad complex rhythm that did not terminate with vasovagal manoeuvres. This abnormal rhythm terminated spontaneously without DC cardioversion. A 12-lead ECG performed subsequently at his local paediatric hospital demonstrated pre-excitation with positive delta waves in lead 1 and in all the precordial leads. On review of the cardiac tracings recorded by the ambulance team it was clear that he was in pre-excited atrial fibrillation with very high conduction rate through the accessory pathway. He was subsequently transferred to our unit for electrophysiology study and ablation of this pathway.
During his initial electrophysiology study, we found that there was a large area of fuse potentials adjacent to the CS and so the presence of a CS diverticulum was suspected and then confirmed on angiography. His accessory pathway was mapped and we found fractionated potentials along a diffuse area surrounding the border of the CS diverticulum. Radiofrequency ablation (RFA) with a non-irrigated tip catheter and subsequently an irrigated tip catheter was performed on the identified bidirectional posteroseptal pathway. An adenosine challenge at the end of the procedure showed persistence of the accessory pathway when the AV node was blocked, but atrial fibrillation could no longer be induced despite high dose isoproterenol. He returned to the ward where he was monitored for a few days. Post procedure ECGs and a repeat adenosine challenge showed no evidence of pre-excitation and he was therefore discharged home on no cardiac medications.
An ECG performed at the outpatient clinic two months after his RFA demonstrated recurrence of pre-excitation. An urgent repeat electrophysiology study was therefore arranged. The CS diverticulum anatomy was further visualised with CS contrast angiography. A posteroseptal pathway associated with the CS diverticulum was again identified and successfully ablated with no evidence of pre-excitation following adenosine challenge at the end of the procedure.
His post procedure ECG and adenosine challenge the following day showed no evidence of pre-excitation. He was therefore discharged home on no cardiac medications to be closely followed up in the outpatient clinic.
Discussion: Radiofrequency ablation is the definitive treatment for children with pre-excited atrial fibrillation. Accessory pathways associated with CS diverticulae can have rapid conduction rates with increased risk of atrial fibrillation and sudden death. They can also be difficult to ablate. All of which were demonstrated by our patient.
