One-year results of the use of endovenous radiofrequency ablation utilising an optimised radiofrequency-induced thermotherapy protocol for the treatment of truncal superficial venous reflux.

Background In previous in vitro and ex vivo studies, we have shown increased thermal spread can be achieved with radiofrequency-induced thermotherapy when using a low power and slower, discontinuous pullback. We aimed to determine the clinical success rate of radiofrequency-induced thermotherapy using this optimised protocol for the treatment of superficial venous reflux in truncal veins. Methods Sixty-three patients were treated with radiofrequency-induced thermotherapy using the optimised protocol and were followed up after one year (mean 16.3 months). Thirty-five patients returned for audit, giving a response rate of 56%. Duplex ultrasonography was employed to check for truncal reflux and compared to initial scans. Results In the 35 patients studied, there were 48 legs, with 64 truncal veins treated by radiofrequency-induced thermotherapy (34 great saphenous, 15 small saphenous and 15 anterior accessory saphenous veins). One year post-treatment, complete closure of all previously refluxing truncal veins was demonstrated on ultrasound, giving a success rate of 100%. Conclusions Using a previously reported optimised, low power/slow pullback radiofrequency-induced thermotherapy protocol, we have shown it is possible to achieve a 100% ablation at one year. This compares favourably with results reported at one year post-procedure using the high power/fast pullback protocols that are currently recommended for this device.

Radiofrequency-induced thermotherapy (RFiTT) in a porcine liver model and ex vivo great saphenous vein.

AIMS: To investigate the thermal spread achieved in porcine liver when using an optimised radiofrequency ablation protocol and correlate findings with the effects seen in ex vivo great saphenous vein (GSV), in order to justify clinical use with the new treatment protocol. MATERIAL AND METHODS: Porcine liver and GSV sections were treated with radiofrequency-induced thermotherapy (RFiTT) using the following settings: 20 W at 1 s/cm (linear endovenous energy density; LEED 20 J/cm), 18 W at 1 s/cm (LEED 18 J/cm), 18 W at 3 s/cm (LEED 54 J/cm), 6 W interrupted pull-back 6 s stationary every 0.5 cm (LEED 72 J/cm). Thermal spread in the liver was measured via digital imaging. GSV sections were sent to an independent laboratory for histological analysis. Previous work suggests a thermal spread of >0.65 mm in liver correlates with transmural thermoablation of a GSV. RESULTS: Parameters giving a LEED of 72 J/cm produced the best results, with a clear transmural effect in the GSV and maximal thermal spread of 1.65 mm, without excessive thermal damage or carbonisation in the ablation tract. CONCLUSIONS: Our porcine liver model correlated well with histological findings and was representative of the thermoablative effects observed in the GSV wall treated with RFiTT. Clinical investigations are now being carried out to investigate the efficacy of this protocol in the clinical setting.

An in vitro study to optimise treatment of varicose veins with radiofrequency-induced thermo therapy.

OBJECTIVE: To develop a reproducible method of using radiofrequency-induced thermotherapy with adequate thermal spread to ablate the whole vein wall in a truncal vein but avoiding carbonisation, device sticking and high impedance "cut outs" reducing interruptions during endovenous treatments. METHODS: Porcine liver was treated with radiofrequency-induced thermotherapy under glass to allow measurements, observation and video recording. Powers of 6-20 W were used at varying pullback speeds to achieve linear endovenous energy densities of 18-100 J/cm. Thermal spread, carbonisation of treated tissue and high-impedance cut outs were recorded. RESULTS: The currently recommended power settings of 18 and 20 W produced sub-optimal results. If pulled back at 3 s/cm to achieve linear endovenous energy densities around 60 J/cm, tissue carbonisation and high impedance cut outs occurred. When high powers and fast pullbacks of 1 s/cm were used, no carbonisation or cut outs occurred but thermal ablation of the liver model was below target due to reduced time for thermal conduction. Low powers (6-12 W) with slow pullbacks (6-12 s/cm) achieved target thermal ablation with minimal carbonisation and high impedance cut outs. CONCLUSIONS: Using low power (6 W) and a slow discontinuous pullback (6 s every 0.5 cm, in steps), we were able to achieve our target thermal ablation in the porcine liver model without carbonisation and high impedance cut outs. This suggests the currently recommended power levels could be reduced, reducing the need to remove the device to clean the electrodes during treatment while achieving target thermoablation of the treated tissue.