Page 194 - Libro vascular I

Chap-12.qxd 29~8~04 14:52 Page 185
ANATOMY OF THE LOWER LIMB VENOUS SYSTEM AND ASSESSMENT OF VENOUS INSUFFICIENCY
proximally, where it will be possible to see the saphenopopliteal junction clearly.
Incompetent Giacomini vein
In some circumstances a large incompetent Giacomini vein may run directly into the SSV, or varicose areas, at the popliteal fossa. Starting in a transverse section just below the popliteal fossa, the SSV is identified and followed proximally. The saphenopopliteal junction should not be seen if it has been correctly ligated. However, the SSV continues to course up the posterior thigh as the Giacomini vein. Alternatively, the superficial vari- cosities may be supplied directly by the Giacomini vein. The Giacomini vein can have a variable supply, as described previously.
Incompetent perforators
These perforators may arise from variable positions and can be found above the popliteal fossa, at the popliteal fossa or from the gastrocnemius vein in the proximal or mid-calf. Perforators arising in the region of the popliteal fossa can follow very tor- tuous routes. Perforators supplying varicose areas in the SSV distribution are easiest to identify in transverse section.
LSV incompetence
Varicose veins in the SSV distribution can occur due to LSV incompetence. Incompetent posterior veins in the LSV distribution, which are not prominent on the skin surface, may run into the SSV system in the upper posterior calf, where the veins become more prominent. The surgeon performing the orig- inal surgery may have assumed that these varicose veins were related to saphenopopliteal junction incompetence and ligated the junction, but in fact the SSV was competent above the point of com- munication between the LSV and the SSV. Therefore, ligation of the saphenopopliteal junction will not have controlled the varicose veins (Fig. 12.22A).
Diffuse varicosities in the popliteal fossa
Diffuse varicosities in the popliteal fossa may resupply the SSV. In this situation, although the saphenopopliteal junction has been ligated, the SSV
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trunk is supplied by numerous small superficial tributaries that are difficult to follow.
ASSESSMENT OF PATIENTS WITH SKIN
CHANGES AND VENOUS ULCERATION
Many patients with venous ulcers have never had varicose vein surgery, whereas others may have had a number of previous operations. However, the basic technique for assessing patients with venous ulceration is similar to the technique for the assess- ment of varicose veins. Many patients are elderly and are unable to stand during the examination, but the leg should be in a dependent position to assess for reflux. This is best achieved by hanging the leg over the side of the examination table with the feet resting on a stool. It is necessary to remove any pressure or compression dressings, as these may reduce venous reflux, leading to false results. Patients with venous ulceration are more likely to have deep venous incompetence or obstruction than patients with simple varicose veins. Therefore, it is impor- tant to assess the deep veins carefully. It is often eas- ier to start the scan by examining the popliteal vein from the popliteal fossa, as many surgeons will not perform superficial surgery if there is gross reflux in the popliteal vein above and below the knee, and a less detailed scan of the superficial vein system may be possible.
There are a number of problems associated with the assessment of patients with venous ulcers. It can be difficult to image the deep veins in obese patients with large legs. In this situation, it may be worth try- ing a 3.5 MHz abdominal transducer to image the deep veins. Sometimes the calf is too ulcerated or sore to perform calf compression for the assessment of reflux. In such cases, try squeezing the upper por- tion of the calf, where there may be less ulceration or skin change. If in doubt, warn the patient that the test could be uncomfortable, as many patients are willing to cooperate but may be distressed if no prior warning of discomfort is given. In rare cases, some analgesia may be required. It can be difficult to assess the competency of veins in patients with continuous high-volume flow (hyperemic flow) in the superficial and deep veins due to infection. The high-volume flow toward the heart can lead to a reduction in reflux duration (Fig. 12.32). Under