Optimizing Transseptal Puncture Guided by Three-Dimensional Mapping: Role of Unipolar Electrogram on Needle Tip

Background and Aims A three-dimensional electroanatomic mapping system-guided transseptal puncture (3D-TSP), without fluoroscopy or echocardiography, was insufficiently reported. Indications for 3D-TSP remain unclear. This study aimed to establish a precise technique and create a workflow for validating and selecting eligible patients for fluoroless 3D-TSP. Methods and results We developed a new methodology for 3D-TSP based on the unipolar electrogram derived from transseptal needle tip (UEGM-tip) in 102 cases (the derivation cohort) with intracardiac echocardiography (ICE) from March 2018 to February 2019. The apparent current of injury (COI) was recorded at the muscular limbus of the foramen ovalis (FO) on UEGM-tip (sinus rhythm: 2.57 ± 0.95 mV, atrial fibrillation: 1.92 ± 0.77 mV), which then disappeared or significantly reduced at central FO. Changes in COI, serving as a major criterion to establish 3D-TSP workflow, proved to be the most valuable indicator for identifying FO in 99% (101/102) of patients compared to three previous techniques (3 minor criteria) of reduction in atrial unipolar or bipolar potential and FO protrusion. A total of 1042 patients in the validation cohort underwent successful 3D-TSP through the workflow from March 2019 to July 2023. ICE guidance was required for 6.6% (69/1042) of cases. All four criteria were met in 740 patients, resulting in a 100% pure fluoroless 3D-TSP success rate. Conclusion Most cases successfully achieved fluoroless 3D-TSP using changes of COI on UEGM tip. Patients who met all four criteria were suitable for 3D-TSP, while those who met none required ICE guidance.