A novel peak frequency mapping algorithm for the precise localization of accessory pathways in the middle cardiac vein: a case report.

Background: Advancements in three-dimensional mapping systems have enhanced the precise accessory pathway (AP) localization and conduction properties. However, accurately identifying the earliest atrial or ventricular activation sites remains challenging, particularly in cases with multiple insertions or epicardial connections. Case summary: A 24-year-old woman with palpitations and a manifest Wolff-Parkinson-White syndrome Type A underwent catheter ablation. Local activation time mapping revealed extensive conduction in the posterior mitral annulus, with a peak frequency (PF) of 291 Hz at the earliest ventricular and earliest atrial activation sites on the endocardium in the omnipolar technology near field (OTNF) mapping. The coronary sinus and middle cardiac vein were additionally mapped using an ablation mapping catheter and a 1.6-Fr electrode catheter. Emphasis mapping identified the Kent bundle location during right ventricular pacing using local activation time and PF mapping. A narrower region of atrial insertion at the entrance of the middle cardiac vein was revealed, with a PF of 645 Hz. The AP connection successfully disappeared 8 s after ablation to the entrance of the middle cardiac vein. At the 3-month follow-up, the patient showed no recurrence of delta waves on the electrocardiogram or related symptoms. Discussion: The novel OTNF concept further enhances this function by differentiating far-field potentials based on annotated PFs. The use of PF values with novel OTNF mapping proved valuable in identifying optimal target sites for the ablation of APs. The combination of OTNF mapping and advanced ablation catheters may enable the precise targeting of specific AP sites.