Open Chest Ablation of a Right Anterior Epicardial Accessory Pathway

Background: Radiofrequency (RF) catheter ablation is currently the treatment of choice in patients with accessory pathways (APs), its success rate being about 95%. Yet, standard endocardial ablation can be challenging especially in case of an epicardial or intramural localization of AP. Alternative approaches to left posterior or postero-paraseptal AP include percutaneous catheterization of pericardial space or epicardial access via epicardial venous system.

Method: A 17-year-old, otherwise healthy male was diagnosed with WPW syndrome. His electrocardiogram showed typical preexcitation. He had been suffering from episodes of palpitations and one episode of syncope while cycling. EP study for assumed right-sided anteroseptal AP was performed using 3D cardiac mapping system. Earliest ventricular activation was documented at the anterior portion of the tricuspid annulus. Pacing maneuvers showed ACERP ≤ 270 ms, IAP 210 ms. Nonsustained ventricular tachycardia (nsVT) could be induced by sensed S3 extrastimuli. However, RF ablation was not successful despite using a long sheath for stabilization of ablation catheter and ablation with irrigated catheter. Also, reablation using high-density mapping and jugular venous access few months later failed. Therefore, mapping of the noncoronary sinus using retrograde approach was conducted. While mapping, catheter accidentally fell into the right coronary artery (RCA) and revealed sharp and very early ventricular signal fused with atrial activation about 15 to 20 mm distally to the ostium of RCA. Mapping was completed without further ablation as ablation either by RF or cryo near the coronary arteries can lead to serious complications like acute coronary syndrome extreme. To confirm suspected epicardial AP, 3D-CT scan of the heart was carried out and revealed a small myocardial bridge crossing the RCA exactly matching up with the spot of earliest ventricular activation. Because of high risk of coronary injury in case of ablation, a surgical approach via inferior partial sternotomy was chosen. Right atrioventricular (AV) groove and aortic root were exposed. Simple epicardial mapping using a decapolar catheter in the right AV sulcus was used to navigate the surgeon during preparation of myocardial bridge. The complete myocardial bridge was dissected and EP study showed no recurrence of preexcitation during incremental atrial pacing. The postoperative course was uneventful. The ECG at 9 months of follow-up showed sinus rhythm without preexcitation. The patient is asymptomatic.

Conclusion: To the authors’ knowledge, this is the first case of open chest surgical ablation of a right anterior to anterolateral epicardial accessory pathway.