Optimising Treatment Parameters for Radiofrequency Induced Thermal Therapy (RFiTT): A Comparison of the Manufacturer's Treatment Guidance with a Locally Developed Treatment Protocol

Linear endovenous energy density (LEED) should always be quoted with the power used in endovenous thermal ablation - results from an in-vitro porcine liver model study

BACKGROUND

Linear Endovenous Energy Density (LEED) is the energy used per cm of vein in endovenous thermal ablation (EVTA) but does not include time. This study examines the effect of time during EVTA.

METHOD

EVTA was performed in a previously validated porcine liver model. LEEDs of 40, 60, 80 and 100 J/cm, using different powers were repeated 5 times each. Thermal spread, tissue carbonisation and device-tissue sticking during treatment were recorded.

RESULT

LEED positively correlated to thermal spread and carbonisation of the tissue. Power was correlated with carbonisation but not thermal spread. Pullback had no correlations with thermal spread or carbonisation. Catheter sticking found occurred in powers >= 15 W or LEED >= 80 J/cm.

CONCLUSION

LEED is a good measure of EVTA but does not include time. Power, which does include time, correlates with carbonisation and with device-tissue sticking. The power used must be quoted with the LEED.

Reducing tumescent anesthetic injection pain by topical anesthesia pretreatment among patients undergoing endovenous radiofrequency ablation of varicose veins: Adouble-blind randomized controlled trial

OBJECTIVES

Tumescent anesthesia frequently causes the intraoperative and postoperative pain during radiofrequency ablation (RFA) of varicose veins. We have to find a way to reduce pain caused by these injections. This randomized controlled trial investigated the effectiveness of topical anesthesia pretreatment (TAP) on relieving needle puncture pain during administration of tumescent anesthesia among patients undergoing RFA of varicose veins.

METHODS

Eligible patients treated with RFA were recruited and randomized to either application of TAP with lidocaine-prilocaine cream (EMLA) or water-based cream (placebo). The primary outcome was patient described pain scores on the visual analogue scale (VAS) at different time points during the procedure. Secondary outcomes were technical success rate, complications, satisfaction level, expense, and extra analgesia use.

RESULTS

Sixty-two patients were randomized: 32 to EMLA and 30 to placebo. Both groups had comparable baseline demographics, CEAP classification, and Venous Clinical Severity Score (VCSS). Less tumescent anesthetic needle puncture pain was found in the EMLA group (22 ± 7 vs 42 ± 8, p < .01). Pain scores of other time points were equivalent. There was less pain in EMLA pretreated area compared to non-pretreated area in the same patient during needle puncture (22 ± 7 vs 45 ± 7, p < .01), and similar phenomena did not appear in the placebo group. There was no statistical difference in complications, satisfaction level, expense, and technical success between the two groups. And no extra analgesia was used in all patients.

CONCLUSION

We recommend the routine use of TAP to reduce the needle puncture pain during tumescent anesthesia in RFA of lower extremity varicose veins.

Vein wall shrinkage induced by thermal coagulation with high-intensity-focused ultrasound: numerical modeling and in vivo experiments in sheep

BACKGROUND

Varicose veins are a common disease that may significantly affect quality of life. Different approaches are currently used in clinical practice to treat this pathology.

MATERIALS AND METHODS

In thermal therapy (radiofrequency or laser therapy), the vein is directly heated to a high temperature to induce vein wall coagulation, and the heat induces denaturation of the intramural collagen, which results macroscopically in vein shrinkage. Thermal vein shrinkage is a physical indicator of the efficiency of endovenous treatment. High-intensity focused ultrasound (HIFU) is a noninvasive technique that can thermally coagulate vein walls and induce vein shrinkage. In this study, we evaluated the vein shrinkage induced in vivo by extracorporeal HIFU ablation of sheep veins: six lateral saphenous veins (3.4mm mean diameter) were sonicated for 8 s with 3MHz continuous waves. Ultrasound imaging was performed before and immediately post-HIFU to quantify the HIFU-induced shrinkage.

RESULTS

Luminal constriction was observed in 100% (6/6) of the treated veins. The immediate findings showed a mean diameter constriction of 53%. The experimental HIFU-induced shrinkage data were used to validate a numerical model developed to predict the thermally induced vein contraction during HIFU treatment.

CONCLUSIONS

This model is based on the use of the k-wave library and published contraction rates of vessels immersed in hot water baths. The simulation results agreed well with those of in vivo experiments, showing a mean percent difference of 5%. The numerical model could thus be a valuable tool for optimizing ultrasound parameters as functions of the vein diameter, and future clinical trials are anticipated.

Efficacy and safety assessment of an ultrasound-based thermal treatment of varicose veins in a sheep model

Purpose: Varicose veins are a common pathology that can be treated by endovenous thermal procedures like radiofrequency ablation (RFA). Such catheter-based techniques consist in raising the temperature of the vein wall to 70 to 120 °C to induce vein wall coagulation. Although effective, this treatment option is not suited for all types of veins and can be technically challenging.Materials and methods: In this study, we used High-Intensity Focused Ultrasound (HIFU) as a non-invasive thermal ablation procedure to treat varicose veins and we assessed the long-term efficacy and safety of the procedure in a sheep model. In vivo experiments were first conducted on two saphenous veins to measure the temperature rise induced at the vein wall during HIFU ablation and were compared with reported RFA-induced thermal rise. Thermocouples were inserted in situ to perform 20 measurements during 8-s ultrasound pulses at 3 MHz. Eighteen saphenous veins of nine anesthetized sheep (2-2.5 % Isoflurane) were then exposed to similar pulses (85 W acoustic, 8 s). After treatments, animals recovered from anesthesia and were followed up 30, 60 and 90 days post-treatment (n = 3 animals per group). At the end of the follow-up, vein segments and perivenous tissues were harvested and histologically examined.Results: Temperatures induced by HIFU pulses were found to be comparable to reported RFA treatments. Likewise, histological findings were similar to the ones reported after RFA and laser-based coagulation necrosis of the vein wall, thrombotic occlusions and vein wall fibrosis.Conclusion: These results support strongly the effectiveness and safety of HIFU for ablating non-invasively veins.

A successful surgical treatment of pulmonary thromboembolism after endovenous radiofrequency ablation with extracorporeal membrane oxygenation bridging

Pulmonary embolism after endovenous radiofrequency ablation is very rare, but a clinically severe complication. Herein, we report a case of pulmonary embolism after endovenous radiofrequency ablation. Early after radiofrequency ablation pulmonary embolism developed and extracorporeal membrane oxygenation implantation was performed. Under extracorporeal membrane oxygenation support, surgical pulmonary embolectomy was performed successfully using the same cannulas and the patient was discharged without any neurological sequelae. In conclusion, although rare after radiofrequency ablation, early recognition of pulmonary embolism and prompt treatment can be life-saving.

Development of a catheter-based technique for endoluminal radiofrequency sealing of pancreatic duct

Introduction: Endoluminal sealing of the pancreatic duct by glue or sutures facilitates the management of the pancreatic stump. Our objective was to develop a catheter-based alternative for endoluminal radiofrequency (RF) sealing of the pancreatic duct. Materials and methods: We devised a novel RF ablation technique based on impedance-guided catheter pullback. First, bench tests were performed on ex vivo models to tune up the technique before the in vivo study, after which endoluminal RF sealing of a ∼10 cm non-transected pancreatic duct was conducted on porcine models using a 3 Fr catheter. After 30 days, sealing effectiveness was assessed by a permeability test and a histological analysis. Results: The RF technique was feasible in all cases and delivered ∼5 W of power on an initial impedance of 308 ± 60 Ω. Electrical impedance evolution was similar in all cases and provided guidance for modulating the pullback speed to avoid tissue sticking and achieve a continuous lesion. During the follow-up the animals rate of weight gain was significantly reduced (p < 0.05). Apart from signs of exocrine atrophy, no other postoperative complications were found. At necropsy, the permeability test failed and the catheter could not be reintroduced endoluminally, confirming that sealing had been successful. The histological analysis revealed a homogeneous exocrine atrophy along the ablated segment in all the animals. Conclusions: Catheter-based RF ablation could be used effectively and safely for endoluminal sealing of the pancreatic duct. The findings suggest that a fully continuous lesion may not be required to obtain complete exocrine atrophy.

Endovenous Celon radiofrequency-induced thermal therapy of great saphenous vein: A retrospective study with a 3-year follow-up

Objective:

Our main objective was to evaluate the short- and long-term efficacy of Celon radiofrequency-induced thermal therapy for endovenous treatment of incompetent great saphenous vein. The secondary objectives were to report on possible short-term side effects and complications.

Methods:

This was a retrospective study of 112 consecutive patients included between 2013 and June 2015. These patients were treated (146 great saphenous vein, C2–C6) either at the hemodynamic room using local anesthesia or at the operating theater under general anesthesia with or without phlebectomy. All patients received radiofrequency-induced thermal therapy at 18 W power, 1 s/cm pullback rate and 5–7 pullbacks per segment of 10 cm (i.e. maximum 10 pullbacks). A clinical follow-up via ultrasound monitoring was done at 1 week, 1 month, 6 months, 1 year, 2 years and 3 years.

Results:

The 3-year survival occlusion rate was 96.71% and 98% for overall and radiofrequency-induced thermal therapy patients, respectively. No major side effects were observed. A case of endovenous heat-induced thrombosis was reported. Slight neurological disorders were reported (0.88%).

Conclusion:

Our unit’s endovenous Celon radiofrequency-induced thermal therapy of incompetent great saphenous vein was efficient, well tolerated, without major side effects. Moreover, in order to reduce possible neurological disorders, we advise multiple pullbacks at 1 s/cm and using tumescence anesthesia.

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 ablation of varicose veins

Background: In the search of alternative techniques to high ligation and stripping (HL/S) in the treatment of varicose veins, catheter-ablation methods have been implemented since 1998. Besides endovenous laser techniques (ELT) radiofrequency ablation (RFA) is a successful device in treating insufficiency of the Great (GSV) and Small saphenous vein (SSV). Methods: This review article sums up publications on Closure Plus™, ClosureFAST™, RFITT® (Celon Method), and EVRF®. It discusses the actually favorized treatment protocols and study results. Results of meta-analysis are presented, too.

Results: The Closure Plus™ catheter was the first radiofrequency technique to be licensed in Europe in 1998. Trials and meta-analyzes show occlusion rates of 81–89 % after 5 years. The consecutive technique was the ClosureFAST™ (CLF) catheter that was introduced in 2007 and offered more standardization in treatment. Published data show occlusion rates of 98 % after 5 years and low profile on complications. Also in 2007 a bipolar radiofrequency technique called RFITT was presented. Due to lack of standards in treatment protocol it could not get accepted as well as CLF despite of good treatment results (92–98 % occlusion rates after 12 months) and low complications. A new RFA device called EVRF® shows weak evidence so far.

Conclusion: Radiofrequency ablation of varicose veins has become a well-established treatment alternative to HL/S mostly represented by CLF.

Radiofrequency ablation of varicose veins: Best practice techniques and evidence

Scope of the review

This article systematically reviews the practice of radiofrequency ablation of lower limb varicose veins. We present the clinical evidence and best practice techniques for currently available devices.

Methods

Manufacturer’s instructions-for-use were requested for all radiofrequency devices. The MEDLINE and EMBASE databases were searched using the following keywords: ‘varicose veins’ AND ‘radiofrequency’ OR ‘radio frequency’ OR ‘Venefit’ OR ‘ClosureFAST’ OR ‘RFiTT’ OR ‘EVRF’ OR ‘VeinCLEAR’, generating 240 articles. Titles and abstracts were screened, yielding 63 articles directly relevant to the scope of the review. Reference lists for publications were also searched to identify further manuscripts of relevance. The Cochrane Database and current National Institute for Clinical and Healthcare Excellence guidelines for varicose veins were also searched from relevant articles.

Results

Four radiofrequency ablation (RFA) systems are currently commercially available. Generic practice methods (common to all RF systems) and device-specific techniques are described. The weight of current evidence relates to the use of Covidien Venefit™ (formerly VNUS ClosureFAST™), which clearly demonstrates clinical advantages over open surgery at least to 2 years follow up. However, contemporary studies of the radiofrequency-induced thermal therapy device (RFiTT®), show that in experienced hands, clinical equivalence to the Venefit™ procedure can be achieved. The evidence base for EVRF® and VeinCLEAR™ devices is currently weak and absent, respectively.

Conclusions

Despite widespread uptake of RFA and acceptance of its clinical advantages over open surgery there is a paucity of Class 1 A evidence. This results from incongruent reporting of clinical outcome measures within existing literature. Similarly, lack of long-term follow-up studies precludes comparison of the durability of short- and medium-term advantages of RFA with the longer term results of open surgery. There remains scope for a large prospective high-quality trial to assess the clinical, anatomical and cost-effectiveness outcomes for the four commercially available RFA devices, with a particular focus on long-term follow up.

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.