m. Eclesiástico que tiene una canonjía

Technique

RFA can also be performed in an outpatient setting with local tumescent anesthesia.

Preparations and introduction are similar to EVLA, with the exception that a only a short sheath is used as the catheter can be advanced without a sheath. The tip of the RFA catheter is navigated 2 cm below the SFJ under ultrasound guidance. A guidewire can facilitate advancement if the GSV is too tortuous to pass. Emptying the vein with a bandage or Trendelenburg positioning may be performed, but is not necessary for the procedure.

The first RFA (VNUS^® Medical Technology, San Jose, CA, US) catheters relied on a ring of employed electrodes, expandable to a maximum of 8-12 millimeter in diameter. The employed electrodes allow direct contact with the vein wall, which is essential in the RFA procedure. Application of tumescent anesthesia is similar to EVLA, and optimizes electrode contact with the vein wall by creating vasospasm. It also provides a protective area for thermal injury. The RFA catheter is then connected to a radiofrequency generator.

A thermocouple on the catheter monitors the temperature of the endothelium, and is able to maintain temperature at a certain level through a feedback system at the generator¹¹⁹. Temperature is normally maintained at 85-90 degrees during withdrawal. The catheter is continuously pulled back at about 3 centimeters per minute, but can be increased with higher temperature settings¹¹⁹. Compression stockings are usually administered for 1-2 weeks after the procedure.

In 2006, the Covidien ClosureFast^TM (Covidien^®, Mansfield, MA, US) catheter, formerly known as VNUS ClosureFast^TM was introduced. This catheter uses segmental ablation in

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contrast with a continuous pullback. A heating element at the distal end of the catheter allows vein segments of 7 centimeters to be obliterated in energy cycles of 20 seconds.

The temperature is maintained at 120 degrees during an energy cycle. When the catheter is placed 2 centimeters below the SFJ, tumescent anesthesia is applied with a recommended volume of 10 milliliters per centimeter of treated vein. This new technology results in a faster treatment time, while every 20 seconds the catheter is segmentally withdrawn for 7 centimeters¹²⁰. Notably, the most proximal part of the GSV is treated with two energy cycles.

Radiofrequency induced thermotherapy (RFITT) (Celon AG, Medical Instruments, Teltow, Germany) is another technique using radiofrequent energy. The RFITT catheter has a rounded tip and contains a acoustic impedance feedback function, ensuring that the energy output is adapted to the size of the vein wall. The bipolar catheter tip needs to moved constantly with a pullback speed of 0.5-1 cm per second, depending on the used power settings of the generator^91,121. An administration of 10-18 W is recommended for RFITT⁹¹.

The only contraindication for RFA is preexistent thrombus in the treated vein. Relative contraindications are comparable to EVLA. Also vein diameters of more than 12 millimeter can now be treated with the ClosureFast^TM catheter¹²².

Mechanism of action

RFA involves the delivery of thermal energy from a bipolar catheter directly to the venous wall. Bipolar electrodes (VNUS Closure^TM) or bipolar catheters (Covidien ClosureFast^TM) are used to generate temperatures of 80-120 degrees Celsius. In contrast to EVLA, RFA requires direct contact of the endothelium with the catheter. Therefore, manual compression on the vein from the outside is recommended by some practitioners to enhance contact during treatment. Adequate tumescent anesthesia and emptying of the vein, prior to treatment, are also possibilities to increases contact of the catheter with the vein.

RFITT uses blood and the surrounding vein wall as a conductor of bipolar energy to generate temperatures up to 60-100 degrees Celsius¹²³. Therefore, the catheter does not need direct contact with the vein wall.

Radiofrequency energy causes acute thermal damage to the endothelium. The heat-related inflammatory response results in endothelial denudation and swelling of the vein wall. It also induces restructuring and repair processes with collagen remodeling and proliferation of fibroblast, leading to complete occlusion of the vein¹²⁴. In a histological

study with bovine veins RFA showed induration and thickening of the vein wall and contraction of the vein lumen¹²⁵. No evidence of vein perforation or thermal damage of the surrounding tissue was observed under macroscopic investigation. However, a complete occlusion was not seen in any of the treated veins. All veins showed a microscopically circular disintegration of the intima. Unfortunately, histological in-vivo studies with RFA are not available to date.

Figure 2. A: radiofrequency generator.

B: magnified view of the ClosureFast catheter. Used with permission of Covidien

Outcome

Several studies have been published on the short and long term efficacy of RFA in the treatment of varicose veins. In 2002, Weiss and Weiss reported the first large series in 140 patients with 90% success rate 2 years after treatment¹²⁶. These patients had complete disappearance of the treated great saphenous vein. The largest prospective study, including 1222 limbs treated with VNUS Closure^TM reported vein occlusion rates after 1 and 5 years of 87.1% and 87.2%, respectively¹²⁷. Clinical improvement was seen in 85%

of the limbs with anatomical success 5 years after RFA. The reported occlusion rates of prospective series are listed in Table 2 and vary between 67-100%10,11,13,78,89,91,106,107,120–

122,124,126–160. First results of radiofrequency segmental ablation were published by Proebstle et al. in 2008¹²⁰. Occlusion rates were 99.6% obtained from 62 limbs after 6 months. Radiofrequency segmental ablation using the Covidien ClosureFast^TM catheter was superior to VNUS Closure^TM, with occlusion rates of 98 and 88% respectively after 1 week¹⁵³. In a randomized controlled study of RFA comparing ligation of the SFJ and surgical stripping, outcome after 2 years was identical¹⁵¹.

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Table 2. Published prospective studies of radiofrequency ablation

Study Year Study design Follow-up

(months)

Chandler et al.¹²⁸ 2000 Prospective 12 120 90

Goldman¹²⁹ 2000 Prospective 6 10 100

Manfrini et al.¹²⁴ 2000 Prospective 6 151 93

Goldman et al.¹³⁰ 2002 Prospective 6 50 68

Merchant et al.¹⁶¹ 2002 Prospective 24 319 85.2

Rautio et al.¹³² 2002 Prospective 10 33 73.3

Sybrandy et al.¹³³ 2002 Prospective 12 26 88

Weiss et al.¹²⁶ 2002 Prospective 24 140 90

Fassaidis et al.¹³⁴ 2003 Prospective 12 59 98

Lurie et al.¹¹ 2003 RCT 4 44 95

Hingorani et al.¹³⁵ 2004 Prospective 1 73 96

Pichot et al. ¹³⁶ 2004 Prospective 25 63 90

Salles-Cunha et al.¹³⁷ 2004 Prospective 9 106 82

Wagner et al.¹³⁸ 2004 Prospective 3 28 100

Lurie et al.¹³⁹ 2005 RCT 24 44 86

Merchant et al.¹⁴⁰ 2005 Prospective 48 1078 88.8

Merchant et al.¹²⁷ 2005 Prospective 60 1222 87.2

Nicolini¹⁴¹ 2005 Prospective 36 330 75

Ogawa et al.¹⁴² 2005 Prospective 1 25 100

Perälä et al.¹⁴³ 2005 RCT 36 15 66.7

Hinchliffe et al.¹⁰ 2006 RCT 1 16 81

Dunn et al.¹⁴⁴ 2006 Prospective 6 85 90

Kianifard et al.¹⁴⁵ 2006 Prospective 12 55 100

Zan et al.¹⁴⁶ 2007 Prospective 24 24 96

Proebstle et al.¹²⁰ 2008 Prospective 6 252 99.6

Calcagno et al.¹²² 2009 Prospective 6 338 99

Boon et al.^{121 *} 2010 Prospective 10 203 89

Goode et al.^{106 *} 2010 RCT 1 87 95

Creton et al. ¹⁴⁷ 2010 Prospective 12 220 97

Gale et al.⁷⁸ 2010 RCT 12 70 84.3

Subramonia et al.¹⁴⁸ 2010 RCT 1 47 100

Haqqani et al.¹⁴⁹ 2011 Prospective 1 73 100

Krnic et al.^{107 *} 2011 Prospective 1 44 86.4

Nordon et al.⁸⁹ 2011 RCT 3 79 97

Study Year Study design Follow-up (months)

Sample size (limbs)

Occlusion rate (%)

Proebstle et al. ¹⁵⁰ 2011 Prospective 36 256 92

Rasmussen et al.¹³ 2011 RCT 12 148 95

Helmy ElKaffas ¹⁵¹ 2011 RCT 24 90 94

Tesmann et al.^{91 *} 2011 RCT 12 66 88.9

Monahan et al.¹⁵² 2012 Prospective 3 27 100†

Zuniga et al.¹⁵³ 2012 RCT 1 355 98

Garcia-Madrid et al.¹⁵⁴ 2013 Prospective 6 67 97

Harlander-Locke et al.¹⁵⁵ 2013 Prospective 6.2 80 100†

Harlander-Locke et al.¹⁵⁶ 2013 Prospective 9 1000 98.6

Park et al.¹⁵⁷ 2013 Prospective 21 60 83.3

Tolva et al.¹⁵⁸ 2013 Prospective 12 407 98

Avery et al.¹⁵⁹ 2014 Prospective 12 241 91

Park et al.¹⁶⁰ 2014 Prospective 24 46 89.1^†

* Radiofrequency induced thermotherapy (RFiTT); ^† Series of SSV

Complications

In the early series of treatment with RFA serious side effects, like paresthesia and skin burns were reported, but these incidences decreased after the induction of tumescent anesthesia with RFA¹⁴⁰. Rates of paresthesia dropped from 14.5% to 9.1% and rates of skin burn decreased from 1.8% to 0.5%. Most events of paresthesia are transient and resolve spontaneously¹²⁷. Below the knee, the saphenous nerve is located adjacent to the GSV.

Therefore, treatment limited to the upper limb can significantly reduce paresthesia¹⁶¹. Other possible complications with RFA are comparable to EVLA. Superficial thrombophlebitis, often described as an erythematous area over the treated vein segment, is inherent to endovenous procedures as obliteration of the GSV requires injury to the vein wall. This self-limiting complication is reported in approximately 5%¹⁶².