Radiofrequency Ablation for Lower Extremity Venous Reflux



Fig. 9.1
The ClosureFast radiofrequency generator and attached 7 cm segmental ablation catheter. The data display shows the catheter temperature (120°C), treatment time (17 s), and power applied to maintain the temperature at 120°C (31 W)



There is a single approved device for RFA of veins in the United States, the ClosureFast™ device (Medtronic; Minneapolis, MN). It utilizes a segmental ablation technique wherein the catheter has a 7 cm distal electrode (and shorter 3 cm electrode for shorter segments or tributaries) which is meant to touch the vein wall circumferentially. Because refluxing veins are much larger than the diameter of the catheter, such direct contact is induced through vasoconstriction of the vein by the surrounding tumescent anesthesia (which commonly includes epinephrine) as well as external pressure applied by the ultrasound probe at the site of the electrode. In this manner the catheter delivers direct controlled heat to the vein wall leading to destruction of the endothelium, collagen contraction and denaturation in the media, and ultimate fibrosis with near permanent vessel closure without coagulating nearby blood. ClosureFast™ was introduced for ablation of the saphenous veins (great, small, or accessory) as an alternative to surgical ligation and stripping. There is also a ClosureRFS™ stylet which is specifically intended for the treatment of incompetent perforator and tributary veins which works along the same principles.



Indications and Limitations


Radiofrequency ablation, like other interventional modalities for the treatment of chronic venous insufficiency of the lower extremities, is indicated in patients with symptomatic CVI. The Society for Vascular Surgery and the American Venous Forum have established clinical guidelines for treatment of patients with venous disease. In those with more severe diseases (C4b, lipodermatosclerosis of the skin; C5, healed ulcers; C6, open active ulceration), they have made several recommendations [6]. In such circumstances, ablation of incompetent superficial veins that have axial reflux directed to the bed of the ulcer or affected skin is recommended, in addition to standard compressive therapy, both to improve ulcer healing and prevent ulcer recurrence or occurrence (Guidelines 6.1–6.4). However, reflecting the relative paucity of prospective randomized trials , all of these recommendations are grade 2 (weak) with a level of evidence of C (weak) except in the case of C6 disease which carries a grade 1 (strong) recommendation based on a moderate (B) level of evidence. In patients with less severe disease, manifested primarily by symptomatic varicose veins (C2) or venous swelling (C3), other clinical guidelines by the Society for Vascular Surgery and the American Venous Forums have been published [4]. These conclude that endovenous thermal ablations (laser and radiofrequency) are safe and effective and recommend them for treatment of saphenous incompetence (Guideline 11.1). In addition, because of the reduced convalescence and less pain and morbidity, they recommend endovenous thermal ablation of the incompetent saphenous vein over open surgery (Guideline 11.2). Both guidelines were strong recommendations (grade 1) with moderate level of evidence (B).

In clinical practice, persistent signs and symptoms of venous disease, after failure of compression medical management, is the usual indication for vein ablation. RFA is most commonly used for ablation of the great or small saphenous veins and, less frequently, anterior or posterior accessory saphenous veins. The use of RFA for perforator veins is approved but less common. Before intervention, a complete venous duplex ultrasound must be performed to document the presence and location of reflux in the respective vein. Abnormal reflux is considered to be retrograde flow of longer than 0.5 s, but most clinicians require the time to be greater than 1 s to be clinically significant [2]. Many symptomatic patients have reflux times greater than 10 s. The refluxing vein needs to be large enough (usually diameter > 4 mm) to be easily cannulated with the RFA catheter. Extremely dilated veins (>20–25 mm) may be considered as a relative contraindication to RFA due to a higher risk of non-closure although successful RFA has been reported in veins as large as 2.5 cm with utilization of sufficient perivenous tumescent infiltration and focal compression [7, 8].

Pregnancy, superficial phlebitis, deep vein thrombosis, and peripheral arterial disease are relative contraindications to RFA . Treatment should probably be deferred to after pregnancy to prevent any potential complications of the procedure that may affect the outcome of the pregnancy and to ensure greater probability of vein closure when the venous hypertension and vein size is decreased. Prior superficial thrombophlebitis with a resulting partially obstructed saphenous vein may make catheter advancement difficult, while RFA in an acutely thrombosed vein can potentially extend the thrombosis. However, ablation of a proximal thrombus-free segment has been reported in patients with distal superficial vein thrombosis by avoiding passing the catheter through the thrombosed segment [9]. Patients with extensive deep venous occlusion should only selectively undergo superficial ablation because the superficial veins in these patients may be important for venous outflow [4]. No data exists regarding the use of RFA in patients with peripheral arterial disease (PAD). In patients with severe PAD, healing of wounds can be more problematic, and therefore management of the arterial disease should first be considered. Immobility, congenital venous abnormalities (e.g., Klippel-Trenaunay syndrome), and advanced systematic diseases that prevent significant improvement in quality of life are other considerations that should be taken into account before proceeding with RFA. Finally, the concomitant use of anticoagulants has not been found to lead either to greater major bleeding complications or lower rates of procedural success [10].

An additional important component before the procedure is appropriate patient counseling in order to explicitly address all of the patient’s expectations. The patient should know about the expected results and possible technical failures such as non-closure and late secondary failure due to recanalization. The options for simultaneous or staged phlebectomy of varicose vein segments should be discussed and patients need to know that untreated varicosities may not completely disappear, other varicosities may later develop, and additional procedures such as phlebectomy or sclerotherapy may be needed in the future [11]. For patients with ulcers, it should be mentioned that ulcer healing will not be immediate and that ulcers may recur as they are not dependent solely on segmental reflux ablation. Potential complications of the procedure, particularly pain, ecchymosis, deep venous thrombosis, skin ulceration, and nerve injury, should be reviewed . Alternative treatments to RFA, including surgical removal, laser ablation , and sclerotherapy, should be discussed. Finally, the use of a detailed informed consent, such as that available from the American Venous Forum, is recommended [12].


Technique


A complete history and thorough physical examination is important, particularly if intravenous sedation is to be utilized and the procedure is performed in an office-based center where less assistance is available. Antiplatelet agents and nonsteroidal anti-inflammatory medications can be continued, but the patient should be informed that these may increase postoperative bruising and ecchymosis. In a similar manner, warfarin anticoagulation is not a contraindication for the procedure, and safe ablations have been reported with successful outcomes in anticoagulated patients without an increase in major bleeding events [9]. No specific guidelines have been established nor published with the use of the new oral direct thrombin or factor Xa inhibitors. However, both with warfarin and other anticoagulants, clinical judgment is employed in anticoagulant management. If the patient is considered to be at low risk of a thromboembolic event, we generally hold warfarin for 2 days and low-molecular-weight heparin and the new oral anticoagulants for 24 h before the procedure. Deep vein thrombosis prophylaxis is generally not used for these usually quick procedures but employed selectively in high-risk patients who are not already on anticoagulation. Determination of high risk can be established with the use of the Caprini scoring system [13], but patients with a history of thrombophlebitis, DVT, and known thrombophilia are generally administered thromboprophylaxis with a single dose of low-molecular-weight heparin before the beginning of the procedure [14]. The usefulness of prophylactic antibiotics has not been studied except in the case of RFA combined with open ligation at the saphenofemoral junction [15]. Nonetheless, the institutionalization of the SCIP (Surgical Care Improvement Project) [16] checklist for prophylactic antibiotics for vascular procedures has resulted in most such patients routinely receiving a single dose of cefazolin antibiotic before vein ablation. Procedural management in both the preparation and treatment of the patient along with optimal documentation has been well outlined by the Intersocietal Accreditation Commission for Vein Centers [17].

Venous duplex ultrasonography is a critical part of not just the preoperative evaluation but the procedure itself. During the diagnostic evaluation of the patient, high-quality venous imaging by an experienced certified vascular sonographer, preferably in an accredited vascular laboratory, will have already examined the saphenous vein for anatomic anomalies such as duplication, areas of obstruction or stenosis from prior episodes of phlebitis, and irregular entry points into the deep venous system. Specific locations of reflux, and refluxing perforating veins that may account for segmental saphenous reflux, will have also been identified [8]. In our practice, on the day of intervention, the ultrasound examination is repeated to confirm reflux in the vein. In circumstances when associated stab phlebectomies are to be performed in association with the RFA, the ultrasound examination must be done before the procedure with the patient in the standing position. The primary purpose is to mark the varicosities that will be treated as these will no longer be as evident with the patient in a recumbent supine position (Fig. 9.2). In these patients, the great or small saphenous vein is also marked along its path as well as the optimal entry point of cannulation for the RFA catheter. Either preoperatively or intraoperatively, this ultrasound examination (preferably by the surgeon) confirms the previous diagnosis and provides visualization of the vein to be treated along with measurement of its size and depth below the surface of the skin.

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Fig. 9.2
In patients in whom stab phlebectomies are to be performed, the patient is marked preoperatively in a standing position with the location of the varicosities to be excised and marked (white filled arrow) as well as the course of the proximal saphenous vein to be ablated (white unfilled arrow) and planned percutaneous entry point of the RFA catheter (black arrow on skin)

After preparing the leg with antiseptic solution and circumferential sterile draping, the patient is placed in a reverse Trendelenburg position and the path of the saphenous vein marked, if not already done so preoperatively. In addition, the location of the saphenofemoral junction is also marked on the skin in the groin so that the length of the ablation catheter that is to be inserted is estimated (Fig. 9.3). Especially in obese patients, simultaneous visualization of both the tip of the catheter and the saphenofemoral junction can be difficult. With the exception of the inadvertent catheterization and treatment of the superficial femoral artery, the worst technical and clinical complication would be heating and ablating the common femoral vein. Measuring the distance to the junction and marking that distance on the catheter with the circular white marker will help to insure that the catheter is not advanced too far into the vein.

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Fig. 9.3
The route of the great saphenous vein is marked intraoperatively on the skin following ultrasound-directed localization. The saphenofemoral junction (black arrow) is separately marked to allow proper insertion and localization of the ablation catheter tip

The percutaneous entry point is selected using ultrasound, either above or below the knee for the GSV, based on easiest accessibility as determined by the size of the vein and its proximity to the surface, as well as the extent of the reflux based on the preoperative ultrasound examination. If entry into the GSV is below the knee, an attempt should be made to locate with ultrasound the site where the saphenous nerve nears the vein, and entry is made above this area to lessen the chance of thermal injury to the nerve. Lidocaine 1% without epinephrine, in order not to induce venospasm, is utilized as a local anesthetic. Similar to other vascular access procedures, we utilize a micropuncture kit with a 21 gauge needle under ultrasound guidance (Fig. 9.4). Such a small needle and its associated 0.018 in. guidewire are less likely to induce venospasm should initial entry not be successful and a repeat attempt be required. Once the guidewire is in place, a 4Fr dilator and sheath is advanced, and intravascular location is confirmed through the free flow of blood after removal of the introducer. A nick is made in the skin next to the dilator with a number 11 blade, and the sheath is upsized by advancing a 0.035 in. flexible J-tip guidewire over which the 7Fr RFA vascular sheath is now advanced (Fig. 9.5). Prior to inserting the RFA catheter, the distance to the saphenofemoral junction is measured and used as the maximal length of catheter insertion (Fig. 9.6). The catheter is thereafter flushed with normal saline and advanced under ultrasound guidance, visualizing the tip as it moves cephalad (Fig. 9.7). The echogenic tip is confirmed to be moving within the saphenous vein, rather than a branch vessel, by the characteristic transverse appearance of the circular vein within the oval saphenous fascia. In order to prevent the development of thrombus within the common femoral vein (endovenous heat-induced thrombosis, EHIT), the tip of the catheter should be distal to the entry of the superficial epigastric vein and 2.5 cm from the saphenofemoral junction (Fig. 9.8) [18]. Simultaneously visualizing both the junction and the tip of the catheter in the same longitudinal plane, particularly in the obese patient, may be challenging, but a concerted effort needs to be made for the surgeon to be convinced that this safe distance is achieved. Occasionally, the catheter does not advance easily up the leg or enters a branch vessel. Most often, this difficulty can be overcome by straightening the leg and manually guiding the catheter as the tip is visualized with ultrasound. On rare occasions, a 0.025 in. Glidewire (Terumo Interventional Systems, Somerset, NJ) can be used to navigate through a tortuous GSV. The tip of the guidewire, however, should not extend into the common femoral vein in order to prevent intimal injury and possible later thrombus development.

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Fig. 9.4
Under ultrasound guidance, a 21 gauge micropuncture needle (arrow) is used to enter the saphenous vein just above the level of the knee


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Fig. 9.5
Over a previously inserted 0.035 in. flexible J-tip guidewire (arrow), the 7Fr vascular dilator and sheath is inserted


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Fig. 9.6
Before insertion of the ablation catheter, the distance from the saphenofemoral junction (white arrow) and the exit from the sheath are measured. This distance will be marked on the catheter by advancing the associated white pledget on the catheter (black arrow)


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Fig. 9.7
The RFA ablation catheter is advanced up the GSV under ultrasound guidance. The catheter (large arrow on ultrasound image) is visualized transversely in the vein which lies within the oval saphenous fascia (thin arrows)


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Fig. 9.8
The tip of the catheter (open arrow) and the distance from the saphenofemoral junction and associate terminal valve (white arrows) are measured longitudinally to assure a separation distance of at least 2.5 cm

Once the ablation catheter is fixed in place, the patient is placed in a Trendelenburg position to decompress the vein in preparation for injection of tumescent anesthesia. Although formulas vary, we utilize 445 mL of 0.9% saline, 50 mL lidocaine 1% with epinephrine 1:100,000, and 5 mL of 8.4% sodium bicarbonate. The volume utilized is 10 mL per length of treated vein. It is injected circumferentially under ultrasound guidance around the great saphenous vein along its entire length from the entry point to the saphenofemoral junction. The use of the 21 gauge micropuncture needle and a motorized pump makes it less painful for the patient and allows for rapid hydrodissection around the vein (Fig. 9.9). The anesthetic agent is useful for vasoconstriction due to the epinephrine, a compressive effect due to its volume, and as a heat sink to prevent adjacent nerve and tissue heating. With appropriate tumescent anesthesia, the patient should not feel any pain on treatment and will have little pain postoperatively. When treating superficial veins, in thin patients, or accessory veins, sufficient tumescence should be infused to move the catheter at least 1 cm from the skin surface to prevent skin burns from the heat.

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Fig. 9.9
Tumescence anesthesia is injected circumferentially around the vein. The location of the vein is best identified by the presence of the catheter within it (red circle), located underneath the saphenous fascia (filled arrows). The tumescent fluid separates the tissues and appears as anechoic areas around the vein (open arrows)

Once tumescent infiltration has been completed, treatment is begun and the electrode heated to 120°C in a 20s pulse cycle. It is important to adequately compress the vein over the full length of the heating element, either using the ultrasound probe or a rolled towel with hand compression. Failure to attain vein wall contact with the electrode may result in incomplete treatment. The proximal portion of the vein is treated with two cycles, and then the catheter is withdrawn 7 cm, according to the markings on the catheter. The remaining portion of the vein is treated segmentally in a similar manner with single cycles. If the vein is of large diameter, many practitioners will perform two cycles of heating for the entire length of the vein. The RF generator initiates power at 40 W, and it is expected that the power output needed to maintain the temperature at 120°C will drop to below 20 W within 10 s. If it does not, or if the temperature is not being maintained even at high power, it suggests insufficient compression or continuing flow within the vein that is cooling the heating element. In such cases, beyond improved compression, additional tumescent infiltration may be needed to constrict the vein. This may also occur in an aneurysmal segment where the vein wall may be thinner and less able to vasoconstrict. Treatment of the less dilated segments proximal and distal to the aneurysmal portion should lead to vein occlusion.

At the completion of treatment, the patient is returned to a supine position, and posttreatment duplex ultrasonography is done to confirm the absence of flow in the entire length of the treated vessel (Fig. 9.10). As the vein is now difficult to visualize, advantage is taken of the skin marking identifying the location of the vein that was drawn at the beginning of the procedure. This is used as a roadmap for the ultrasound probe. In addition to examining the ablated vein, continued phasic flow and compressibility in the common femoral vein needs to be demonstrated. We also make it a point to document pulsatile arterial flow in the adjacent femoral artery to confirm that there was no inadvertent vasoconstriction of the artery caused by tumescent infiltration into that vessel. With the same concern, the pedal pulses are palpated before taking the patient off the table. There is no retreatment protocol with RFA. If continued flow is seen in the vein, the catheter should not be readvanced as it may perforate the vessel and heat surrounding nerves or other tissues. The patient should instead be followed clinically, and, if needed, surgical treatment or sclerotherapy may be utilized.

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Fig. 9.10
After treatment is completed, color duplex ultrasound demonstrates continued cephalad flow and compressibility in the common femoral vein (CFV) and in the remnant patent portion of the GSV (white arrow). Antegrade flow in this portion of the GSV is dependent on continued patency of the superficial epigastric vein (not seen in this image). The more distant treated portion of the GSV (black arrow) appropriately has no flow

There is no widespread agreement on the need or type of compression to be utilized at the end of the procedure. If no associated stab phlebectomies have been performed, many physicians will utilize compression stockings for 1 week that the patient may have been wearing before the procedure. Our present protocol is circumferential stretch bandaging (Ace) from the foot to the thigh for 48 h. This appears to be helpful symptomatically and may decrease ecchymosis. Finally, prior recommendations were for post-procedural duplex scanning at 48–72 h [4]. However, the incidence of pulmonary embolism and deep venous thrombosis is low, many clinicians have not found this practice useful, and this recommendation is now being reviewed for revision by the American Venous Forum. Our own practice at present is to do a follow-up ultrasound within a week of the procedure in order to both document successful venous closure and investigate for possible development of deep venous thrombosis or EHIT.


Outcomes


Since the introduction of RFA as a technique for ablation of refluxing veins , multiple studies have shown that short- and midterm clinical results are comparable to those achieved with surgical ligation and stripping. Several studies have shown anatomical vein occlusion rates of 90–95% with RFA [1921]. Balint et al. [22] performed a meta-analysis on 17 studies and 1420 limbs with great saphenous vein incompetence and evaluated outcomes of EVLA, RFA, and ultrasound-guided foam sclerotherapy. Technical success rates were 89% for RFA, 85% for EVLA, and 33% for ultrasound-guided foam sclerotherapy . There were no significant differences between the three techniques regarding vein reopening or recanalization.

Another meta-analysis of seven studies with at least 2 years of follow-up showed that the overall rate of recurrent varicose veins increased with length of follow-up, but it was similar after endovenous ablation versus ligation and stripping with both being 22%. However, the cause of recurrence was different in the two groups. Neovascularization was seen more often in the surgical group, while recanalization was the most common cause of recurrence in endovenous ablations, followed by the development of anterior accessory saphenous vein incompetence and incompetent calf perforating veins [23]. These differences in cause of recurrence can affect treatment plans. Postoperative neovascularization in the groin can be more difficult to treat because of surgical scarring and the small and tortuous size of the vessels which makes percutaneous interventions much more challenging. After endovenous ablations, however, recanalized veins can be treated reasonably easily with repeat endovascular ablation or sclerotherapy.

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Jan 19, 2018 | Posted by in CARDIOLOGY | Comments Off on Radiofrequency Ablation for Lower Extremity Venous Reflux

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