Characterization of a successful transseptal access with an electrified guidewire: An ex vivo ovine study

BACKGROUND: The determinants of successful transseptal puncture (TSP) using an electrified guidewire (ETSP) have not been studied. OBJECTIVE: We used an ex vivo ovine model to identify the determinants for successful ETSP. METHODS: 25 fresh ovine hearts were dissected, and lateral right atrial/appendage tissue was excised to create an interatrial septum (IAS) model. The sheath and guidewire were fixed to a custom-made jig, which allowed linear displacement to model clinical catheter manipulation. We observed TSP at varying degrees of IAS displacement (0, 5, 10, and 15 mm) and guidewire tip protrusion (1, 3, and 5 mm). Electrocautery was applied to the proximal end of the guidewire at 15 W in the "Coag" mode for 2 seconds to attempt ETSP. The thermal profiles of the various configurations during electrification were studied using thermal imaging. Finally, thermal assessment of ETSP was studied by comparing 2 common waveforms ("Coag" and "Cut") at 15 W. RESULTS: A total of 58 ETSP runs were performed. The model with a 1-mm wire protrusion and an IAS displacement of 10 mm yielded a probability of 100% to achieve TSP with a single 2-second application. Extended guidewire protrusion (3 and 5 mm) and no IAS displacement resulted in unsuccessful puncture and increased the risk of high tissue temperatures and larger thermal lesions. The "Coag" waveform produced lower peak temperature (34.36°C ± 3.17°C vs 68.6°C ± 3.7°C; P < .0001) and smaller thermal footprint (2.9 ± 0.2 mm vs 5.1 ± 0.2 mm; P < .0001), while maintaining perforation success compared with the "Cut" waveform. CONCLUSION: Displacement of the IAS is required for successful ETSP. Guidewire protrusion beyond 1 mm resulted in inconsistent perforation and increased tissue temperature.