Tissue Puncture Effectiveness
The RF wire required on average 1.10 ± 0.47 attempts to cross the septum. The 0.014” electrified guidewire required an overall mean of 2.17 ± 2.36 attempts (2.0 times as many as the RF wire; p<0.01), and the 0.032” electrified guidewire required an overall mean of 3.90 ± 2.93 attempts (3.5 times as many as the RF wire; p<0.01, Figure 3A). Across power output levels, the 0.014” electrified guidewire required a range of 1.2-2.6 times as many applications as the RF wire, and the 0.032” electrified guidewire required 3.4-4.1 times as many attempts as the RF wire to perforate the septum (Figure 3B). The number of RF applications was significantly more consistent for the RF wire than both 0.014” and 0.032” electrified guidewires (p<0.001, Figure 3B). Increase in the power applied to electrified guidewires, from 20W to 50W, did not significantly improve the consistency in TSP success. Across all power settings, the 0.014” and 0.032” electrified guidewires failed to puncture the septum in 6% and 19% of tissues, respectively. The RF wire did not fail to perforate any of the tissue specimens.
While the dilator-wire tip distance had no measurable effect on the rate of successful puncture using the RF wire, an increase in distance from 1mm to 5mm reduced TSP effectiveness for both 0.014” and 0.032” electrified guidewires (Figure 3C). At 1mm dilator-wire tip distance, all wires perforated the septum on the first attempt. However, increasing the distance to 3mm and 5mm required more RF attempts and introduced variability in the TSP effectiveness, especially for electrified guidewire. At the maximum dilator-wire tip distance tested (5mm), the 0.014” electrified guidewire required 5.8 ± 3.4 attempts for TSP and failed to puncture in 40% of the septa after 8 attempts, while the 0.032” electrified guidewire failed to puncture in all septa after 8 attempts (Figure 3C).