Comparison of laser power output from the fiber tip during endovenous laser ablation against displayed power and the "first treatment" effect.

OBJECTIVE: International guidelines recommend endovenous laser ablation as one of the first-line treatments for truncal venous reflux associated with varicose veins. Clinicians use linear endovenous energy density to measure the energy used during treatment. The aim of this study was to investigate the power output from the fiber tip and to see if this changed with use. METHODS: We placed 15 mL of water in a thermally insulated 25-mL beaker. Two thermocouples were placed equidistantly adjacent to the laser fiber tip. A 1470-nm laser was fired at 5W for 2 minutes and the temperature change was measured. Three fibers were used on different days to allow the laser to cool for 24 hours between fibers. Each fiber was tested three times in a row. We also tested the "first treatment" effect by comparing the power output when the fiber was fired immediately after the laser was switched on, compared with treatments when the laser had been switched on for 1 hour. To assess whether this was due to the console being "cold" on the first firing of the day, we repeated the experiment having switched on the laser console 1 hour before firing to "prewarm" the console. However, the diode was not fired during this hour. To measure fiber degradation, three runs of the experiment were performed successively before firing the laser continuously for 20 minutes, then three more runs were conducted, resulting in delivery of approximately 10,000 J. RESULTS: The actual power output seemed to be lower than the console suggested. The power output from the first fiber used in a succession of three with the same laser had a significantly lower power output than the following two runs (P = .0004 and P < .0001, respectively). When the laser was prewarmed for 1 hour without firing, no change in this output pattern was noted (P = .293). Fiber degradation was not found in any of the fibers that were tested within the maximum recommended for the fiber (10,000 J). CONCLUSIONS: The first use of a fiber in a treatment session has a significantly lower power output from the treatment tip than subsequent uses, even if the machine is prewarmed and the console displays the same power for each. The authors believe that this phenomenon is due to the diode being less efficient when first used after switching it on. Clinicians need to be aware that the true power output at the fiber tip may not be as indicated by the console display and may be variable during a treatment session.

Pattern of thermal damage and tissue carbonisation from endovenous radiofrequency ablation catheter - Using an in vitro porcine liver model.

BACKGROUND: Successful endovenous thermoablation relies on transmural vein wall ablation. We investigated the pattern of thermal spread and tissue carbonisation from RadioFrequency-induced ThermoTherapy (RFiTT) at different powers and pull back methods, using a porcine liver model. METHODS: We used a previously validated in-vitro porcine liver model. Different powers from 5-25 W were used to administer 150 J. We compared continuous and pulsed energy delivery. Length, lateral spread, and total area of thermal damage, together with any tissue carbonisation, was measured using digital analysis software. RESULTS: All experiments used 150 J total energy. Total thermal damage area was smaller with lower power and pulsed energy. Continuous energy caused more tissue carbonisation than pulsed except at 25 W. CONCLUSION: Reduced thermal damage with lower power or pulsed energy results from cooling due to increased time of treatment. Increasing the power increases tissue carbonisation. Optimal treatment is determined by the highest power used continuously that does not cause tissue carbonisation.

Histopathologic differences in the endovenous laser ablation between jacketed and radial fibers, in an ex vivo dominant extrafascial tributary of the great saphenous vein in an in vitro model, using histology and immunohistochemistry.

OBJECTIVE: The study aimed to investigate the biologic effects of the 1470-nm endovenous laser (EVL), with a jacketed fiber and a radial fiber, during EVL ablation of an ex vivo dominant extrafascial tributary of the great saphenous vein in our in vitro model by histology and immunohistochemistry. METHODS: Ten segments of the dominant extrafascial tributary of the great saphenous vein were harvested by a consultant vascular surgeon from patients during routine varicose vein surgery. Six segments were treated using an ex vivo model of our design by a 1470-nm EVL with a jacketed fiber. The other four segments were also treated by a 1470-nm EVL but with a radial-firing fiber. Each segment was split into five sections and treated at five different linear endovenous energy densities (LEEDs) at 10 W: 0, 20, 40, 60, and 80 J/cm. The veins were incubated and subsections collected at 6 and 24 hours after treatment. Subsections were immersed in buffered formalin and taken for histologic and immunohistochemical analysis. Histopathologic analysis was then performed. RESULTS: Treatment with the radial fiber led to a pattern of damage that was more homogeneous than with the jacketed fiber, with no carbonization of tissue present. Significant transmural damage and necrosis were observed at LEEDs of 60 and 80 J/cm in both treatment groups. At the same LEEDs, p53 and caspase 3 analysis showed that transmural cell wall vein death (necrosis or apoptosis) occurred by 6 hours after treatment with both fibers. CONCLUSIONS: There was a significant difference in the effects of treatment with a jacketed fiber and a radial fiber in EVL ablation in vitro. Although both fibers caused transmural vein wall cell death at similar LEEDs, the pattern of damage with the radial fiber was more homogeneous. There was no overtreatment of tissue in terms of carbonization after treatment with the radial fiber. Treatment with the jacketed fiber showed carbonization of tissue at the same LEEDs.

A description of the 'smile sign' and multi-pass technique for endovenous laser ablation of large diameter great saphenous veins.

Aims To report on great saphenous vein diameter distribution of patients undergoing endovenous laser ablation for lower limb varicose veins and the ablation technique for large diameter veins. Methods We collected retrospective data of 1929 (943 left leg and 986 right leg) clinically incompetent great saphenous vein diameters treated with endovenous laser ablation over five years and six months. The technical success of procedure, complications and occlusion rate at short-term follow-up are reported. Upon compression, larger diameter veins may constrict asymmetrically rather than concentrically around the laser fibre (the 'smile sign'), requiring multiple passes of the laser into each dilated segment to achieve complete ablation. Results Of 1929 great saphenous veins, 334 (17.31%) had a diameter equal to or over 15 mm, which has been recommended as the upper limit for endovenous laser ablation by some clinicians. All were successfully treated and occluded upon short-term follow-up. Conclusion We suggest that incompetent great saphenous veins that need treatment can always be treated with endovenous laser ablation, and open surgery should never be recommended on vein diameter alone.

Pelvic venous reflux in males with varicose veins and recurrent varicose veins.

Objectives To report on a male cohort with pelvic vein reflux and associated primary and recurrent lower limb varicose veins. Methods Full lower limb duplex ultrasonography revealed significant pelvic contribution in eight males presenting with bilateral lower limb varicose veins. Testicular and internal iliac veins were examined with either one or a combination of computed tomography, magnetic resonance venography, testicular, transabdominal or transrectal duplex ultrasonography. Subsequently, all patients received pelvic vein embolisation, prior to leg varicose vein treatment. Results Pelvic vein reflux was found in 23 of the 32 truncal pelvic veins and these were treated by pelvic vein embolisation. Four patients have since completed their leg varicose vein treatment and four are undergoing leg varicose vein treatments currently. Conclusion Pelvic vein reflux contributes towards lower limb venous insufficiency in some males with leg varicose veins. Despite the challenges, we suggest that pelvic vein reflux should probably be investigated and pelvic vein embolisation considered in such patients.

Implication of foam sclerosant inactivation by human whole blood in a laboratory setting.

Background During sclerotherapy, it has been recommended to confirm intravenous placement of the needle by aspirating blood into the sclerosant syringe. This may inactivate some, or all of the sclerosant. Aims To quantify the volume of human blood needed to completely inactivate 1 ml of sodium tetradecyl sulphate, and comparing fresh blood and blood that has been stored in an ethylenediaminetetraacetic acid tube. Methods A series of manual titrations were carried out following a procedure developed at STD Pharmaceutical Products Ltd (Hereford, UK) and listed in the British Pharmacopeia. Three percent of sodium tetradecyl sulphate stock solutions were made with increasing volumes of blood and titrated against benzethonium chloride to determine the active concentration (% w/v) of sodium tetradecyl sulphate remaining in the solution. Results A calculated approximation showed 0.3 ml of blood is required to fully inactivate 1 ml of 3% sodium tetradecyl sulphate when made into a foam. A comparison was made between the use of fresh blood and blood stored in ethylenediaminetetraacetic acid tubes. Blood stored in ethylenediaminetetraacetic acid tubes showed more inactivation of sodium tetradecyl sulphate, but this was not significant at the P ≤ 0.05 level. Conclusion The data from our study have shown that a minimum of 0.3 ml of fresh blood is required to inactivate 1 ml of 3% sodium tetradecyl sulphate as a foam and it is not significantly affected by storing blood in an ethylenediaminetetraacetic acid tube. Our methodology suggests that during foam sclerotherapy treatment, blood should not be aspirated into the syringe to confirm position, and that ultrasound guidance is more appropriate for needle placement.

Anatomical abnormalities of the pelvic venous system and their implications for endovascular management of pelvic venous reflux.

Background Pelvic venous reflux is often treated with pelvic vein embolisation; however, atypical pelvic venous anatomy may provide therapeutic challenges. Methods We retrospectively reviewed seven patient files and reported symptoms, diagnostic imaging, aberrant anatomy and means by which the interventional radiologist successfully completed the procedure. Any follow-up data were included if available. Results Four anatomical abnormalities were found: internal iliac veins draining into the contralateral common iliac vein, duplicated inferior vena cava, reverse-angle renal veins with atypical left ovarian vein drainage and direct drainage of the internal iliac vein to the inferior vena cava. All patients were successfully treated with pelvic vein embolisation. Conclusion Abnormal embryologic development may cause variable pelvic venous anatomy. Knowledge of this will enable interventional radiologists to successfully treat such patients.