Late activation mapping guided slow pathway ablation in a patient with persistent left superior vena cava

Slow pathway ablation can be technically challenging in patients with persistent left superior vena cava (PLSVC) due to the distortion of the Koch triangle and dilated coronary sinus. There is no consistent approach to localize the slow pathway (SP) in these patients as conventional landmarks do not apply. Over the last few years, new approaches have been proposed. Hale et al.1 validated SP visualization in normal hearts using ripple or sparkle mapping to identify the latest activation in the inferior septum. A 29-year-old patient with dilated cardiomyopathy and transvenous implantable cardioverter-defibrillator (ICD) received inappropriate shock therapy. At electrophysiological studies, PLSVC was noted. Coronary sinus atrial pacing at 550–660 ms resulted in frequent non-re-entrant non-sustained tachycardia with 1 : 2 atrioventricular node (AVN) response (Figure 1A), suggestive of dual atrioventricular nodal non-re-entrant tachycardia (DAVNNT). We proceeded with high-density mapping of the right atrial septum using a PentaRay™ catheter in sinus rhythm to create a local activation map of the atrial septum. A His cloud was demarcated with the His electrogram signals manually excluded from the map. Local activation time (LAT) was annotated to the peak negative dv/dt in the unipolar electrogram by the system. A discrete late atrial activation zone was identified along the tricuspid annulus, which was associated with a fractionated corresponding atrial electrogram (Figure 1B), representing the SP ablation target.1 A single-radiofrequency application to that area led to transient 1 : 2 response, resembling clinical tachycardia, and subsequent successful SP modification, as confirmed by arrhythmia non-inducibility and elimination of dual atrioventricular nodal physiology. (A) Coronary sinus (CS) pacing demonstrating dual atrioventricular nodal non-re-entrant tachycardia (DAVNNT). (B) Modified left anterior oblige (LAO) view. His cloud is demarcated. The latest activation area with fractionated atrial electrogram represents the slow pathway location (purple zone). A, atrium; CS, coronary sinus; H, His; PLSVC, persistent left superior vena cava; V, ventricle. Our proposal is to use a LAT map to display similar information in a single image that is intuitive to understand. An additional advantage of such an approach is the elimination of fluoroscopy. To our knowledge, this is the first case describing SP modification using the LAT map in a patient with PLSVC and DAVNNT. The demonstrated new approach may allow rapid and precise SP localization in challenging cases. Consent: The authors confirm that written consent for submission and publication of this case report including image(s) and associated text has been obtained from the patient in line with COPE guidance. Funding: Self-funded.