Nonthermal Ablation of Saphenous Reflux

Overview

MOCA (ClariVein) has the longest follow-up and was the first of the new NTNT technologies to be reported. The device was developed by Michael Tal and John Marano ( Fig. 8.1 ). First human cases were performed in February 2009. There are two components to the device/technique: (1) a mechanical component, which is a rotating wire ( Figs. 8.2 and 8.3 ) that breaks down the surface tension barrier between sclerosant/blood and vein wall; and (2) chemical installation of a detergent liquid sclerosant sodium tetradecyl sulfate (STS) or polidocanol (PLD) simultaneously. The mechanical disruption allows for penetration of the sclerosant so that medial damage and scarring can occur leading to occlusion. The wire rotates at 3500 rpms, which also causes vein spasm, so sclerosant is not being injected into a vein filled with blood ( Figs. 8.4 and 8.5 ). The technique is not sclerotherapy. Each component, mechanical and chemical, is essential for good results. Alone, each component yields poor results. The sclerosant exits the catheter sheath about 2 cm from the tip of the rotating wire, it is pulled up the rotating shaft of the wire and is released from the tip thus directly “injecting” sclerosant into the damaged vein wall (see Fig. 8.5 ). This action allows for penetration of sclerosant subendothelial to aid in media damage. One can think of the rotating wire as a sprinkler releasing sclerosant from the tip. In the original trial, all veins received 12 mL of 1.5% STS liquid. A pullback rate of 1.5 mm per second or 1 cm every 7 seconds was used. This was chosen because of the similarity to the existing laser pullback rates at that time. The volume of sclerosant used was irrespective of the length of the vein being treated. Occlusion rate was 96% at 1 year with minimal complications; no deep venous thrombosis (DVT), nerve, or skin damage. Venous clinical severity score (VCSS) improved, as expected with an occluded GSV. Greater than 2-year follow-up was reported by the same group with 96% occlusion rate.

Technique

The technique has undergone some modifications since the original report as all new techniques or technologies do. Here are the current recommendations.

• 1.

  Micropuncture access with ultrasound guidance

• 2.

  Placement of a 4-Fr or 5-Fr micropuncture sheath into the vein

• 3.

  No further wire or sheath exchanges required, no tumescence required

• 4.

  Passage of the angled catheter portion of the device up the targeted vein

• 5.

  Attachment of the motor unit and unsheathing of the wire placement of the wire tip 2 cm from the saphenofemoral junction (SFJ) or just at the fascial curve of the saphenopopliteal junction (SPJ)

• 6.

  Volume of sclerosant determined by diameter and length treated (table available) 8 to 10 mL GSV, 4 to 5 mL SSV

• 7.

  Begin rotation only, no injection for the first centimeter of pullback to induce vein spasm, that is, from position 2 cm to 3 cm from SFJ

• 8.

  After 1 cm of rotation, begin drip infusion of the sclerosant while continuing pullback; the patient only feels a vibration

• 9.

  Maintain constant rate of pullback (1.5 mm/s) with continuous drip infusion; reload syringe when needed

• 10.

  Posttreatment, have patient flex ankles to wash out any sclerosant in deep system

• 11.

  Wrap legs as per your protocol; this author uses 4-inch and 6-inch ACE from midthigh overnight and then no further compression unless a concomitant phlebectomy

• 12.

  Have patient ambulate; may resume normal activity next day

Technical Pearls

• Pearl 1: The pullback rate is much more important for success than sclerosant volume. When failures are analyzed, the operator pulled too fast and did not allow enough time for elimination of the sclerosant vein wall surface tension. In the original study, all veins received 12 mL of 1.5% STD, regardless of length treated. No DVT occurred. Obviously, some veins received a little too much and some got a little too little, yet a 96% occlusion rate was achieved with no DVT/skin/nerve injury. The technique is forgiving for volume but not forgiving of pullback rate. It is better to pull too slowly and give too much sclerosant than the contrary. The type of detergent sclerosant does not affect outcomes. Researchers from the Netherlands have reported comparable results with PLD 2% combined with 1%.

• Pearl 2: Confirm placement of the wire before starting treatment with ultrasound; ultrasound visualization is not routinely needed during the pullback. If there is a larger segment of vein (> 8–10 mm), then the ultrasound probe is used to partially compress that section to improve vein wall contact. However, routine pressure may lead to the rotating wire getting caught on the vein wall. If in fact it ever does, as happens in around 5% of cases, a quick jerk of the wire will free the catheter. This is akin to pulling a bandage quickly off the skin. During the procedure, one needs to listen to the motor rotating because the first sign of the catheter getting caught is a change in pitch of the motor, and the second sign is the patient having a pulling sensation. The wire cannot be broken by pulling it.

• Pearl 3: If doing concomitant phlebectomy, this author recommends access and placement of the MOCA device, but no treatment until the phlebectomy segment is completed. The axial superficial vein is then treated. This sequence minimizes the potential dwell time of sclerosant in the deep system, and thus minimizing the risk of DVT. There are no studies to demonstrate this theoretic issue. The reported DVT rate worldwide is less than 0.5%.

• Pearl 4: When imaging posttreatment, it is important to not only use ultrasound greyscale but color flow duplex as well. With MOCA, the vein is immediately occluded, but it takes 3 to 6 months longer to contract ( Fig. 8.6 ).

  

Therefore any early ultrasound with greyscale will show a dilated vein. This finding is in contrast with TT ablation. The additional use of color flow duplex will document absence of flow.

As with most other endovenous treatments, the postprocedure compression and activity instructions have become less onerous. This author uses compression for 24 hours post-MOCA which is similar for any endovenous procedure. Any and all activity is allowed the next day. These instructions apply only when phlebectomy is not included.

Results

To date, more than 20 articles have been published regarding MOCA (ClariVein) in peer-reviewed literature, and over 100,000 cases have been done worldwide. The results are overwhelmingly coincident with occlusion rates greater than 90% and significant improvement in QoL measures. Some detailed studies, which address specific topics, will be discussed.

One of the longest follow-up has been reported by this author of the original clinical trial at greater than 2 years. Witte et al. found similar improvement in QoL measures and occlusion at 3 years. van Eekeren et al. reported equal results at 1 year when using PLD instead of STS. In addition, all the QoL measures improved at 1 year.

One of the advantages of any NTNT technology is safety and no risk of nerve injury when treating any below-the-knee (BK) segment of vein. Boersma et al. reported 1-year results for MOCA when treating SSV. No nerve injury occurred, and the occlusion rate was 94%. These results are encouraging in that SSV treatment has the concern of potential injury to three nerves; sural, tibial, and peroneal. Many physicians have been loath to treat the SSV because of nerve risk and DVT. This study did not have either issue.

The management of more advanced disease states, such as C6 ulcer patients, is another advantage of NTNT technologies. In C6 patients, if the axial disease reflux is to the ankle, it is desirable to treat the entire pathologic segment. Tumescence is hard to place in an area of ulceration and significant lipodermatosclerosis. This author has used retrograde cannulation of the GSV in these circumstances with good results. Moore et al. have reported the use of MOCA in a C6 patient with SSV incompetence with good results. Finally, three studies compared MOCA with radiofrequency ablation (RFA). van Eekeren et al. concluded that MOCA yielded less postoperative pain, faster recovery, and faster return to work than RFA. Bootun et al. randomized 119 patients to MOCA or RFA. MOCA had lower intraoperative pain scores, with equal occlusion rate and QoL improvement compared with RFA. Finally, Lane et al. published the final results of a trial comparing MOCA with RFA, which showed equivalent improvement in QoL measures.

The mechanism of action of MOCA has been better understood in recent years. Two articles, one by Boersma and one by Whiteley, illustrate that both components (mechanical and chemical) are needed for successful treatment with MOCA.

Summary

MOCA currently has the longest follow-up of any NTNT technology. Studies support its use for the great majority of incompetent superficial axial veins. All studies comparing MOCA with RFA show as good, if not better, results regarding patient pain during and after, return to normal activities, and any other QoL scores. There are unique advantages of the NTNT techniques and of MOCA specifically. At the conclusion of this chapter, a summary of the benefits, indications, and contraindications of all the TT and NTNT technologies will be discussed.