Endovenous Thermal Ablation




Introduction


Chronic venous disorders (CVD) of the lower extremity are common problems caused by venous hypertension. In many cases, CVD are the result of incompetent valves in one or more of the saphenous veins and their primary tributaries. In patients with saphenous vein incompetence, regardless of CVD stage, treatment begins with the elimination of these incompetent pathways. Until recently, the best way to accomplish this was with ligation of the saphenous vein at its deep vein junction and removal of the abnormal saphenous vein segments, with a procedure known as high ligation and stripping (HL/S). Over the last few years, HL/S has been replaced by endovenous thermal ablation (EVTA). In this chapter we will review EVTA in detail.


The EVTA techniques currently available are endovenous laser ablation (multiple wavelengths and laser fiber kits marketed by multiple vendors, see Box 9.1 ) and RF segmental thermal ablation (ClosureFast (CF), VNUS Medical Technologies Inc., San Jose, CA). The first EVTA tool was radiofrequency ablation or RFA (Closure and later Closure Plus, VNUS). EVTA with RFA was extensively investigated and utilized successfully, but was recently replaced with CF. Laser has been primarily performed with 600 micron bare tipped fibers. However, some manufacturers have utilized fibers ranging from 400–1000 micron and one vendor utilizes a fiber with a glass cap on the tip surrounded by a metal cylinder around the cap and distal 2 cm of the fiber. There is limited data comparing the different configurations at this time.



Box 9.1

Endovenous laser wavelengths, commercially available





  • 810 nm Diode Laser (AngioDynamics Queensbury, NY)



  • 940 nm Diode Laser (Dornier MedTech Americas, Inc., Kennesaw, GA)



  • 980 nm Diode Laser (Biolitec, Inc., East Longmeadow, MA)



  • 1320 nm (CoolTouch, Roseville, CA)



  • 1470 nm (Biolitec)




Both ELA and CF are effective treatments for saphenous incompetence. Both procedures are associated with high success and low complication rates. The underlying goal for all three EVTA procedures is to deliver sufficient thermal energy to the wall of an incompetent vein segment to produce irreversible occlusion, fibrosis and ultimately disappearance of the vein. The procedures are generally performed on an ambulatory basis with local anesthetic and typically require no sedation. The patients are fully ambulatory following treatment and the recovery time is short.




Patient Selection


The selection of candidates for EVTA involves a directed history and physical examination as well as a duplex ultrasound (DUS) examination. The details of the clinical and DUS examination have been discussed in other chapters. Indications for endovenous treatment are listed in Box 9.2 and the contraindications to endovenous treatment are listed in Box 9.3 .



Box 9.2

EVTA Indications




  • I

    Symptoms of venous insufficiency affecting quality-of-life



    • i

      Aching


    • ii

      Throbbing


    • iii

      Heaviness


    • iv

      Fatigue


    • v

      Restlessness


    • vi

      Night cramps


    • vii

      Pruritis


    • viii

      Spontaneous hemorrhage



  • II

    Skin changes associated with chronic venous hypertension



    • i

      Corona phlebectasia, eczema and pigmentation


    • ii

      Lipodermatosclerosis


    • iii

      Atrophie Blanche


    • iv

      Healed or active ulceration


    • v

      Edema


    • vi

      Superficial phlebitis (SVT) in varicose veins



  • III

    Cosmetic (restorative) concerns


  • IV

    Anatomical indications



    • i

      Significant reflux documented on duplex ultrasound (DUS) examination (reflux >0.5 seconds)


    • ii

      Straight vein segment


    • iii

      Intra- or epi-fascial vein segment meeting other anatomical criteria that can be pushed away from the skin with tumescent anesthetic


    • iv

      Reflux responsible for venous hypertension leading to the clinical abnormalities



  • V

    Ambulatory patient without contraindication




Box 9.3

Relative contraindications to EVTA





  • Pregnancy or nursing female patients (concerns related to anesthetic use and heated blood effluent which may pass through the placenta to the fetus)



  • Obstructed deep venous system inadequate to support venous return after EVTA



  • Liver dysfunction or allergy making it impossible to use a local anesthetic (cold saline may be useful as an alternative)



  • Allergy to both amide and ester local anesthetics (cold saline may be an alternative)



  • Severe uncorrectable coagulopathy (EVTA is anecdotallysafe with Warfarin use if INR <2)



  • Severe hypercoagulabilty syndromes (where risk of treatment outweighs potential benefits despite prophylactic anticoagulants)



  • Inability to wear compression stockings secondary to inadequate arterial circulation, hypersensitivity to the compressive materials or musculoskeletal or neurological limitations to donning the stocking itself



  • Inability to adequately ambulate post-procedure



  • Sciatic vein reflux



  • Thrombus or synechiae in the vein or tortuous vein making passage of an endovenous device impossible (unless multiple access points are chosen)




Treatment of incompetent superficial truncal veins in patients with previous deep vein thrombosis requires a careful assessment of the adequacy of the patent segments of the deep venous system. It also requires a risk stratification as to the risk of post-procedural thrombosis. EVTA is appropriate if the deep system is adequate enough to support venous drainage and the superficial venous incompetence is responsible for symptoms or skin changes. If the patient has any ongoing risk for thrombosis EVTA may still be appropriate if that risk can be decreased with prophylactic anticoagulants. If saphenous reflux is seen with venous ulcers with an adequate deep venous system, EVTA of the causative veins is necessary to minimize the risk of a recurrent ulceration


Treatment of competent enlarged superficial venous segments has no proven medical benefit and should not be performed. In some cases the enlarged vein may be functioning as a re-entry or collateral pathway for another source of reflux or deep vein obstruction.


The use of ELA and RFA to close incompetent perforating veins has been described. At this point the indications and contraindications for use as well as the success rates and safety of this approach have only recently begun to be evaluated.




Applications


EVTA has been successfully and safely used to ablate the great and small saphenous veins, the anterior and posterior accessory great saphenous vein, the superficial accessory saphenous vein, the anterior and posterior circumflex veins of the thigh as well as the thigh extension of the small saphenous vein, including the vein of Giacomini. EVTA has been used to treat long straight competent tributary veins outside the superficial fascia, particularly in patients who are obese and in whom either sclerotherapy of microphlebectomy would be difficult, time consuming or prone to side effects.




Evta Equipment


Equipment and supplies common to ELA and CF are listed in Box 9.4 . A foot pedal controlled pump (AngioDynamics or HK Surgical) can be used to infuse the perisaphenous anesthetic infusion as an alternative to hand injection. Venous access kits that allow the use of a less traumatic 21 gauge needle to insert a 0.018 in guidewire are useful when accessing small veins but do add expense to the procedure. These kits include a 4 or 5F sheath with a dilator tapered to the 0.018 in guidewire. After the sheath and dilator are inserted the dilator and 0.018 in guidewire can be removed to allow the placement of a standard 0.035 in guidewire. (Cook, AngioDynamics, Vascular Solutions or Merit Medical).



Box 9.4

Equipment common to ELA and CF





  • Procedure table that can tilt to Trendelenberg and reverse Trendelenberg



  • DUS with at least a 7.5 MHz transducer



  • Sterile gowns, gloves, masks, drapes, gauze



  • Ultrasound gel, sterile ultrasound probe and cord cover



  • Antiseptic preparation fluid



  • Local anesthetic



  • No. 11 or 15 scalpel blade



  • 18–21 gauge needle for percutaneous entry



  • 21–25 gauge needle for administration of tumescent anesthesia



  • Syringes



  • Normal saline



  • Compression stockings




Additional materials required to perform ELA include the laser generator (available from several vendors), sheath long enough to cross the abnormal venous segment(s) usually included in a kit along with a guidewire and sterile laser fiber. Additional components needed for CF include the VNUS radiofrequency generator, introducer sheath, CF catheter and guidewire.


ELA is usually performed by placing a 4 or 5F sheath into the vein to be treated over a 0.035 in guidewire and then, after inserting a laser fiber into the sheath, withdrawing the sheath to expose the fiber tip. The sheaths are manufactured in multiple lengths and generally the sheath chosen is as long or longer than the segment(s) to be treated. The fibers are generally bare tipped, 600 micron in diameter and are usually premarked to allow the operator to know when the fiber is tip to tip with the end of the sheath as well as when they extend a fixed distance beyond the tip. In very straight veins, a laser fiber can be advanced beyond its sheath to the starting point of ablation, but advancement through the sheath is recommended to avoid passing the fiber through the vein wall.


An 11 cm long 7F sheath is used with the CF catheter. The CF catheter is available to 60 cm or 100 cm lengths. The CF catheter is 7F in diameter and after introduction of its sheath, it can be passed into the vein over a 0.025 in guidewire although the manufacturer has found guidewire use is necessary in only a minority of cases. The catheters have a resistive element at the distal 7 cm that heats to a fixed temperature when activated. The catheters are marked in 6.5 cm intervals to fascilitate segmental withdrawal after activation that builds in a 5 mm overlap for each segmental treatment.




Tumescent Anesthesia


Tumescent anesthetic, when used in phlebology, describes the use of large volumes of dilute anesthetic solutions that are infiltrated into the perivenous space of the veins to be treated. The rationale behind the use of large volume tumescent anesthesia for EVTA include (a) its use as a local anesthetic, (b) its ability to extrinsically compress and empty the vein to maximize the contact of the thermal device and the vein wall for efficient thermal transfer to the vein wall as well as (c) providing a protective heat sink around the treated vein to minimize heating of adjacent structures.


ELA and CF is usally performed with a dilute tumescent anesthetic solution of Lidocaine in normal saline (a concentration of 0.1% lidocaine is typically used with an average volume of about 5–10 mL/cm of treated vein) with or without epinephrine, often buffered with sodium bicarbonate. This should be delivered with ultraound guidance into the perivenous space (saphenous sheath) of the vein to be treated. If can be injected either manually or with an infusion pump such that upon completion of the process the vein is surrounded along its entire treated length with the anesthetic fluid as demonstrated in Figure 9.1 .




Figure 9.1


Tumescent anesthetic should be delivered in copious volumes in the perivenous space of a vein to be treated with EVTA. ( A ) The DUS axial image demonstrates an axial US image of the GSV before tumescent anesthetic. ( B ) Demonstrates the hypoechoic halo of tumescent anesthetic fluid after it has been injected around the GSV


Although the maximum safe dosage of lidocaine using tumescent technique for venous procedures is not well studied, 35 mg/kg with epinephrine has been reported as safe in the plastic surgical literature. However, one should keep in mind the FDA reviewed circulars accompanying units of lidocaine state a maximum does of 5 mg/kg without and 7 mg/kg with epinephrine with each use.




Evta Technique


The steps common to both ELA and CF are:



  • 1

    Perform preprocedural DUS to map the venous segments to be treated. Mark the course of the vein(s) to be treated along with important anatomical landmarks associated with the ablation on the skin including the proposed venous access site(s) and deep vein junctions. The access site is ideally at the inferior end of the incompetent segment or segments of the treated vein. In most cases, the entire incompetent segment(s) can be treated with one puncture. If microphlebectomy will be performed along with EVTA, the veins to be removed should be marked at this time as well.


  • 2

    Prepare the operative tray and equipment. Aside from the thermal ablation device and a venous access kit, only basic supplies such as gauze, a sterilizing solution, sterile barriers, as well as the tumescent solution, with delivery syringes and needle and an ultraound probe cover are needed.


  • 3

    Position the patient on the procedure table to allow visualization of the veins that need treatment. This is generally supine but the prone position is preferred for treatment of the SSV or Vein of Giacomini. Elevation of the torso of the patient relative to the legs will prolong venous distention and enhance the likelihood of successful venous access. Carry out sterile preparation and draping of the leg to be treated. Pre-procedural antibiotics are not necessary in almost all circumstances as the procedure is performed sterilely and is considered “clean”.


  • 4

    Visualize the access site with DUS. Placing the patient in a reverse Trendelenberg or partly sitting position will keep the vein more distended and may facilitate venous access.


  • 5

    Anesthetize the access site. Nick the skin just large enough to facilitate entry of the sheath through the skin.


  • 6

    Insert the access needle into the GSV under ultrasound guidance. Use of a 21G puncture set, as discussed previously, is preferred by one author in all cases (N.K.) and by the other author (S.Z.) when the target vein is <4 mm in diameter. Cutdown is rarely needed and used only if percutaneous access fails.


  • 7

    Place a 0.035 in guidewire into the vein.


  • 8

    Confirm intravenous placement with ultrasound.


  • 9

    Place the introducer sheath over the wire.


  • 10

    Fully advance the short sheath for CF. Position the sheath for ELA to the starting point for ablation. One author will typically advance the ELA sheath beyond the starting point and later withdraw it with the laser fiber to the starting spot. The movement of withdrawal helps in accurately identifying the tip and in positioning it at the starting point.


  • 11

    Remove the wire and its dilator if one is used with the sheath. Check for venous return by aspirating the syringe attached to the sheath and flush. Recognize that the sheath tip maybe against the vein wall and may not aspirate freely. Also realize when flushing, micro bubbles of air introduced into the vein may produce an acoustic shadow that may limit the ability to see venous detail and device positions.



Additional steps for ELA include:



  • 1

    Introduce the laser fiber into the sheath so that the fiber reaches the sheath tip. There is generally a mark on the fiber to show this. Then fix the laser fiber and carefully pull back the sheath to expose about 2–3 cm of fiber. One should then withdraw the entire sheath-laser fiber to the ablation starting spot.


  • 2

    Fine tune the location of the tip of the laser fiber to just below the superficial epigastric vein, AAGSV or other large junctional vein for the GSV, and just below the thigh extension junction (or parallel to the skin and just beyond the segment that dives toward the popliteal vein when a thigh extension does not exist) with the SSV for SSV ablations ( Fig. 9.2 ). For closure Fast, place the device 1-2 cm below saphenofemoral junction (SFJ) or saphenopopliteal junction (SPJ).




    Figure 9.2


    ( A ) GSV and SSV. ( B ) Anatomy of the right saphenofemoral junction.

    Modified from a drawing by Pentti Rautio


  • 3

    Connect the laser fiber to its generator and confirm that tip is in the correct general location by viewing visible light that can be delivered into the laser fiber tip and visualized through the skin ( Fig. 9.3 ). This is an additional way to ensure that the tip of the laser is being visualized accurately and that the laser connections were made appropriately. If the light is not seen in the expected location the operator should troubleshoot the position of the laser or the connection to the laser to understand why.




    Figure 9.3


    Aiming beam of the laser fiber tip visible through the skin during ELA


  • 4

    Administer tumescent anesthesia with ultrasound guidance after the patient has been placed into the Trendelenburg position to help drain the vein.


  • 5

    Place appropriate laser safety goggles on everyone in the procedure room and use other appropriate laser safety measures. Connect the laser fiber to the laser and verify proper laser settings. Setting recommendations vary, but as will be discussed aim to deliver at least 70–80 J/cm length of vein treated: at 14 W this is achieved with a maximum pullback rate of 2 mm/s.


  • 6

    Set the laser to continuous mode and select the power to be used. Re-verify placement of the laser tip with ultrasound ( Fig. 9.4 ).




    Figure 9.4


    Longitudinal (sagital) ultrasound image of the saphenofenoral junction demonstrating a 400 micron laser fiber tip in the great saphenous vein (GSV) just below the superficial epigastric vein (SEV). FV, femoral vein


  • 7

    Activate the laser and withdraw the fiber and sheath at the speed that is dependant on the amount of energy you wish to deliver at the power setting selected with the laser in continuous mode. One author will deliver 70 J/cm 14 W continuous mode at 810 nm throughout. The other author (NK) uses more energy for the first 10 cm (140 J/cm) and less as the laser tip progresses lower down the leg (100 J/cm to the knee and 70 J/cm below the knee). This is done to ensure closure vein of the proximal, where failure occurs most, and to decrease the risk of nerve injuries lower in the leg (see Technical comments ).


  • 8

    Stop laser energy delivery at the distal aspect of the vein and place the laser in standby mode.


  • 9

    Remove the fiber/sheath from the vein. Be sure the entire fiber is removed to exclude the possibility of a fracture of the device intravascularly.


  • 10

    Record the watts, laser on-time, total joules delivered and length of the segment treated. Calculate the withdrawal rate and joules delivered per cm to ensure you have reached the targets for successful ablation.



Additional steps for ClosureFast (CF) are as follows:



  • 1

    Introduce the 7F ClosureFast catheter through its sheath either bare or over a 0.025 in guidewire and position its tip to the desired starting position 2 cm below the deep junction. Connect the CF catheter to the RF generator.


  • 2

    Deliver tumescent anesthesia and place the patient in the Trendelenburg position as discussed previously.


  • 3

    Withdraw the sheath so that one of the 6.5 cm marks on the catheter is located at the point the catheter exists the sheath.


  • 4

    Activate the generator perform two 20 second heating cycles at the preset temperature of 120°C. Withdraw the catheter 6.5 cm and repeat the heating cycle until the entire vein is ablated. The second 20-second cycle is recommended by the manufacturer at the first treatment site although some operators will perform second cycles at all levels or selectively at levels with aneurysmal segments or near large tributaries, such as an incompetent perforator to ensure thorough ablation.


  • 5

    When the amount of vein left to treat is <7 cm long, marks will be visible on the catheter to alert the operator. The sheath should be withdrawn at this point to allow the heating element to extend beyond the sheath to ensure vein treatment as well as to avoid heating the sheath or the skin. Cease treatment when the catheter tip enters the introducer sheath or exits the vein.


  • 6

    Remove the CF catheter and sheath after the final ablation.


  • 7

    Record the parameters, duration of treatment, and length of segment treated ( Fig. 9.5 ).


Apr 10, 2019 | Posted by in Dermatology | Comments Off on Endovenous Thermal Ablation
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