In vitro study of a radiofrequency guidewire aimed at recanalization of totally occluded peripheral arteries

Abstract

A novel radiofrequency ablative system (40 msec-train pulses with twenty 200 msec pulses at the carrier frequency of 750 KHz and 1 Hz repetition rate) aimed at recanalizing totally occluded peripheral arteries was investigated by means of in vitro tissue ablation from human postmortem arterial wall samples. The samples were submitted to irradiation with a guidewire 150 cm long, maximum diameter of ceramic tip 0.033 inch positioned perpendicular to the tissue surface in saline, contrast medium or blood using varying generator power. Ablation efficacy was determined as the depth of vaporization per pulse delivered. Electrical current for the train duration was measured as voltage at the 1 ohm-resistor. In saline, the ablation efficacy increased from 8 to 65 microns/pulse with generator power increasing from 11 W to 27.5 W. There was no significant difference in the ablation efficacy between saline and blood. In contrast medium, the ablation efficacy was significantly lower. For the same generator power, the electrical current varied during the ablation procedure from 1.3 +/- 0.2 A at the beginning of the procedure to 1.1 +/- 0.2 A after the first pulses and to 2.0 A before artery wall perforation occurred. Neither tissue ablation nor current variations were observed when radiofrequency energy was emitted on calcified tissue. The diameter of craters was 0.89 +/- 0.1 mm (range: 0.85-0.96 mm). No major thermal injury such as carbonization or charring was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Radio frequency perforation of cardiac tissue: Modelling and experimental results

“…Microscopic studies of RF delivery (PEARCE, 1986;DUFFY and COBB, 1995;HINDRICKS et al, 1989;AN et al, 1989) have demonstrated discrete areas of desiccated and coagulated tissue, for low electrical field intensity, and minimum thermal damage around the perforated site for high electrical field intensity (PEARCE, 1986;DUFFY and COBB, 1995;MELNIK et al, 1994). As for the time course of the applied voltage, we suggest that continuous AC delivery is preferable to pulsed AC delivery to minimise collateral damage.…”

A wire in every lesion

“…Today, we have wires that vibrate [I] and others that emit sound [2] or electromagnetic energy [3]. In this issue, Melnik and colleagues [4] add a spark to this race by examining the potential for radiofrequency (RF) energy as a wire booster. Their thin (0.033-inch), flexible RF guidewire outperformed holmiun and excimer lasers in terms of both penetration depth and channel width, but it was no match for calcium.…”