Large-electrode, impedance-sensing RF transseptal system reduces unintended left atrial injury during transseptal puncture

Background Powered radiofrequency (RF) guidewires are increasingly used for transseptal puncture (TSP) in procedures that require left atrial (LA) access. However, unintended LA tissue damage can occur if RF energy continues to be delivered via the electrode after TSP. This tissue damage can lead to cardiac tamponade, great vessel perforation, and valvular damage. Objective Determine if a large-electrode (LE) RF guidewire with an impedance-sensing auto shut-off generator reduces inadvertent LA tissue damage, as compared to a small-electrode (SE) RF guidewire system with pre-programmed RF duration in an ex-vivo porcine cardiac model. Methods Guidewires with LE (length >25mm) and SE (length <1mm) were evaluated in an ex vivo swine heart model (n=3). Hearts were excised, perfused with saline, and connected to a pulsatile pump to maintain anatomical pressure & flow. TSP was performed at the interatrial septum (IAS) using three power settings: 1s Pulse mode (1sP), 1 or 2 sec Constant mode (1sC, 2sC) for SE, and 30-50W for LE. Endoscopic videography was collected in the right atrium (RA) and LA before and after TSP. RF power data were extracted per manufacturer’s instructions. Primary endpoints were TSP success, occurrence of unintentional LA tissue effects, RF duration, and cumulative RF energy. Results Both guidewire systems successfully performed TSP. Upon crossing the IAS and contacting LA tissue, the SE produced visible heating and tissue defects in 8 / 11 TSPs (73%). LE produced no visible effects in TSPs (0/11, 0%) (p < 0.001). Mean RF duration for LE system was 223 ± 51 ms, compared to the SE system with pre-programmed RF duration of 1s or 2s. The mean total energy delivered by the LE system was 4.8 ± 1.1 J, compared to 12.7 ± 7.5 J for the SE system (p = 0.006). Conclusion In an ex-vivo porcine model, LE guidewires used with an auto shutoff generator for TSP were associated with a 0% rate of unintended LA tissue effects compared to 73% for SE. Mean RF duration was reduced by 1,277ms (85%) and mean energy delivery was reduced by 7.9 J (62%). Further studies are needed to determine the clinical benefit of these differences.