Performance Assessment of a Radiofrequency-Powered Guidewire for Crossing Peripheral Arterial Occlusions Based on Lesion Morphology

Abstract

The goal of this study was to assess and to compare the performance of a conventional guidewire and a radiofrequency (RF)-powered guidewire for crossing various types of peripheral chronic total occlusions as characterized by magnetic resonance imaging. In this study, 27 samples of peripheral arterial plaques were excised from two amputation patients. To characterize the lesion morphology, each sample was imaged with 7T magnetic resonance imaging using ultrashort echo time and T2-weighted (T2W) sequences (97 × 97 × 97 μm3 voxels) and imaged with micro-computed tomography (50 × 50 × 50 μm3 voxels). The lesions were categorized as “soft” (fat, thrombus, microchannels, or loose fibrous tissue—bright on T2W images) or “hard” (dense fibrous tissue/collagen and segmented calcium—gray on ultrashort echo time and dark on T2W images)1-3 as shown in Fig 1. Using a custom catheter test station, the load cell advanced the guidewires at a constant velocity of 0.05 mm/s while recording the exerted forces. The performance of a 0.035-inch conventional hydrophilic guidewire was compared with a 0.035-inch RF guidewire with RF power (on; 50W maximum at 468 kHz) and without RF (off). For hard lesions, the conventional guidewire failed to penetrate (n = 6), whereas the RF guidewire successfully punctured (n = 3) with forces of 1.34 ± 0.36 N when off and significantly lower forces of 0.54 ± 0.12 N when on (n = 3; one-tailed t-test; P < .03; Fig 2). For soft lesions, the conventional guidewire penetrated the samples (n = 5) with puncture forces of 0.25 ± 0.20 N, whereas the RF guidewire experienced forces of 0.62 ± 0.28 N when off (n = 5) and 0.04 ± 0.03 N when on (n = 5; one-way analysis of variance; F(2,12); P < .002). These results indicate that using RF power significantly reduces the required amount of force to puncture hard lesions; where the conventional guidewire fails, the RF guidewire succeeds. Future work will analyze the safety aspect of using RF in vivo.