Pretreatment Ultrasound Mapping

Duplex venous scanning is the essential pretreatment investigation prior to either sclerotherapy or UGS of major varicose veins and truncal incompetence. Through duplex scanning, patterns of venous incompetence will be found to be extremely variable and often unexpected. Duplex scanning involves B-mode imaging of the deep and superficial veins combined with directional pulsed Doppler assessment of blood flow. Color-duplex imaging superimposes blood flow information onto the B-mode ultrasound image, permitting visual assessment of blood flow while creating an anatomical map of the venous anatomy. The details of venous duplex examination have been described in a previous chapter and will not be dealt with here.

In short, duplex examination is able to provide an accurate anatomical and physiological map of superficial and deep venous incompetence and localize points of reflux from the deep to superficial venous system. With duplex examination a detailed map of reflux paths in the superficial system, from the proximal origin of the reflux (usually from the deep system) to a distal reentry point, can be created. This map will allow optimal decisions regarding sclerotherapy intervention and will ensure that all significant areas of reflux are addressed by treatment and, conversely, that all normal veins are preserved.7 Diameters of major veins and junctions are also recorded during the duplex examination. These measurements may influence various parameters of the treatment process including selection of sclerosing agent and foam, and postsclerotherapy compression.

Following the duplex examination, the treatment process then is directed toward eliminating all the incompetent superficial pathways mapped out with duplex ultrasound, and then in the posttreatment phase, reexamining with duplex to ensure that the reflux pathways have not recana-lized prior to complete fibrosis of the vein that usually occurs between six to 12 months following initial treatment.

TECHNIQUES OF ULTRASOUND-GUIDED SCLEROTHERAPY (UGS)

Sclerosing Agents

Generally, only relatively strong sclerosants are used in UGS. In an international survey8 of 44 phlebologists who were known to use UGS extensively, 95% used sodium tetradecyl sulphate (STS) (Fibrovein™; STD Pharmaceuticals, Hereford, England), and 5% used 3% polidocanol (POL) (Aethoxysclerol™; Kreusler Pharma, Wiesbaden, Germany). There was a small minority of phlebologists that used polyiodinated iodine as an alternative solution in particular circumstances, such as in the presence of allergy to STS or at deep to superficial junctions. With sclerosant concentration, generally 3% STS was used although some phlebologists use STS in various strengths from 0.75% to 2%.

In this survey, 34% of phlebologists used foamed sclerosants with STS again being the most common agent used as foam. It is likely that the ratio of phlebologists using foam sclerosants compared with solution foam has increased significantly since that survey, as the benefits of foam have become more widely known. The use of foam is described in more detail in another chapter.

In a recently published study,9 STS and POL, in both solution and foam formulations were shown to have similar efficacy, tolerability, and patient satisfaction. There is good evidence, however, that POL is a weaker detergent type of sclerosant than STS10 and higher concentrations are necessary to produce complete vascular sclerosis for any given diameter of vein (see Table 20.1).11

This is the most likely reason why the majority of phle-bologists prefer STS when performing UGS, as in general, larger truncal veins are being treated with this technique.6

Patient Positioning

For treatment of veins on the medial aspect of the leg, patients are placed in the supine position with the treated leg level and externally rotated at the hip. The knee is usually

TABLE 20.1 Approximate Equivalent Concentrations of STS and Polidocanol Required for Effective Sclerosis of Increasing Caliber of Lower Limb Veins

Vein caliber mm

STS concentration

%

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