Venography

Technique

Diagnostic ascending venography requires a 22-gauge catheter, three 20–30-mL syringes, two tourniquets, a tilting fluoroscopic table with footrest, C-arm fluoroscopy, contrast agent, and normal saline. In addition, a 4F micropuncture sheath should be available for direct access to the venous system through the popliteal vein if needed. Ascending venography begins with placement of a catheter in a peripheral vein of the distal extremity. The access device is usually a 22-gauge intravenous catheter inserted into a superficial vein on the dorsum of the foot. When the affected extremity has significant edema, percutaneous catheterization of peripheral veins becomes difficult. In such cases, the use of ultrasound to guide vascular access is helpful. It is important that access for ascending venography not be through the saphenous vein adjacent to the medial malleolus at the ankle because contrast material may preferentially fill the superficial venous system without demonstrating the deep venous system adequately. The likelihood of this problem can be decreased by placing a tourniquet at the ankle and one at the knee, which will drive the contrast material into the deep venous system. However, these tourniquets should be released just before image acquisition to relieve extrinsic compression and to avoid occlusion of the deep veins. The patient is placed on a tilting fluoroscopic table with a footrest to enable near-upright positioning. With the patient initially in a reverse Trendelenburg position, the table is tilted to recumbency as the bolus is tracked. This approach enhances visualization of the large-capacity lower extremity venous anatomy as gravity delays the outflow of contrast material. The contralateral lower extremity is supported with a small platform so that no weight is borne on the extremity being examined. Side grip handles can be placed on the table as needed, depending on the patient’s comfort level and security in the semi-upright position.

The examination is begun with the patient in a 40- to 60-degree semi-upright position. The intravenous contrast bolus is followed by radiographic imaging as it flows to the central veins. As the contrast agent ascends, additional filming of the deep and superficial femoral veins is performed. At least two projections are needed in the tibial and popliteal locations. Approximately 50 to 100 mL of contrast material is needed to fill the deep venous system adequately from ankle to groin. Additional contrast material can be injected, as needed, to visualize problem areas. Even with appropriate venous access and the use of tourniquets, adequate opacification of the deep veins of the lower extremities may be difficult because of dilution of the contrast agent and preferential flow from deep to superficial regions, which allows contrast material to escape to the superficial system. In such cases, we place the patient in the prone position, access the popliteal vein under ultrasound guidance, insert a 4F micropuncture sheath, and inject contrast material into the deep venous system. At completion of the examination, the veins are flushed with 50 mL of normal saline to minimize contact of the contrast agent with the venous endothelium and the chance for development of thrombophlebitis. It is important to make sure the skin over the accessed vein is cleansed appropriately to reduce the risk of infection.

Interpretation

The classic venographic sign of venous thrombosis is a luminal filling defect with a surrounding rim of contrast ( Figs. 28.1–28.3 ). This appearance of parallel lines of contrast material around the thrombus is referred to as the “tram-track” sign. Other indicators of thromboembolism are an abrupt termination of intravascular contrast or the formation of a meniscus. However, correct and consistent interpretation of lower extremity venography to rule out DVT may be challenging. Intraobserver disagreement about the probable presence or absence of thrombus has been shown to occur in up to 10% of venography cases. The invasive nature of the technique, the exposure to radiation, and the improvement and availability of ultrasound technology have made venography a secondary technique for the detection of acute and chronic venous thrombosis. However, venography does play a primary role in the treatment of DVT, allowing for localization and use of mechanical thrombectomy devices to treat acute venous thrombosis with the use of angioplasty or placement of stents in the setting of chronic venous scarring.

Technique

Ascending venography for incompetent perforating veins involves the injection of contrast material into a foot vein with a tight tourniquet around the ankle to occlude the superficial veins such that reverse flow from the deep veins into the superficial veins through the incompetent perforating veins can be seen. A translucent ruler may be used to measure the location of the incompetent perforating vein from the tip of the medial or lateral malleolus. The table is then moved through the horizontal position and into Trendelenburg position, and flow of contrast material is followed under fluoroscopy. Lateral views are especially important in the thigh for accurate localization of a midthigh perforating vein. After a perforating vein is identified, a tourniquet can be used above that level to direct the contrast agent into any incompetent perforating vein.

Interpretation

Thomas and Bowles compared ascending venography with varicography for identification of incompetent perforating veins. Sixty-one lower extremities of 50 patients were examined with both methods. Incompetent perforating veins of the gastrocnemius muscle and midthigh were more accurately shown with varicography than with ascending venography ( Fig. 28.4 ).

Technique

The technique used is the same as when ascending venography is performed. Direct puncture varicography is most useful for the evaluation of venous malformations ( Fig. 28.6 ). Ultrasound-guided access provides the ability to perform this type of venography. In patients being treated for venous malformations, access can be difficult and painful. In such cases, either general or regional anesthesia may be useful and should be considered.

Interpretation

Focal dilation of the deep or superficial venous system is diagnostic of venous aneurysms and malformations. Because of the small number of venous aneurysms included in most series, no single diagnostic method has been reported to be superior. However, most series do report color-flow duplex examination to be valuable in the diagnosis of popliteal venous aneurysms and to provide information on the presence of mural thrombus. Gillespie et al. reported that venous aneurysms were correctly diagnosed in 85% of patients with imaging techniques: phlebography (60%), color-flow duplex scanning (27%), and magnetic resonance imaging (MRI) (10%).

Passive filling of the vascular tree after compressive exsanguination of an extremity, extrinsic occlusion of its arterial supply, and venous drainage has been shown to be a useful technique for evaluation of venous malformations. Closed-system venography was performed in 17 patients, and it correctly identified 11 of 12 surgically confirmed vascular abnormalities. There were no false-positive findings.

Technique

Descending venography requires a tilt table, C-arm fluoroscopy, short 4F or 5F straight catheter with distal side holes, syringes, and contrast agent. It is performed on a tilt table to allow examination in the 40- to 60-degree upright position. Descending venography requires direct catheter access into the deep veins. In most cases, the venous access site is the common femoral vein contralateral to the side of interest. The catheter is advanced to the inferior vena cava (IVC) and then to the iliac vein and common femoral vein of the symptomatic lower extremity. A short 4F or 5F straight catheter with distal side holes is positioned at the junction of the external iliac and common femoral veins. For unilateral examination the catheter is placed from the ipsilateral femoral vein, and for bilateral examination a single femoral vein puncture is used. A transjugular approach may be used to direct the retrograde catheter into both extremities from a single access site. The contralateral lower extremity is supported with a platform, as with ascending venography, so that the extremity being examined will be relaxed and bear no weight. With the catheter tip in the common femoral vein, the table tilted to a 60-degree semi upright position, and the patient bearing weight on a block placed under the nonexamined extremity, contrast material is injected and followed with fluoroscopy as it flows caudad through the incompetent venous valves. A total of 10 mL of contrast material is slowly injected by hand at a rate of 5 mL/s. As the contrast material is injected, the patient breathes normally, after which the patient is instructed to bear down and perform a Valsalva maneuver to enhance evidence of valvular incompetence. Specific areas of interest can be further studied by sequential injections of contrast to optimize image capture of valve location and function and the extent of reflux.

Interpretation

Although superficial varicosities are frequently present, they are rarely a prominent feature of symptomatic advanced chronic venous disease. Most patients with symptoms of CVI who undergo venography have reflux into the deep venous system. The two main abnormalities that cause venous valve reflux are postphlebitic and primary valvular incompetence, with the latter being more common. Although venous duplex evaluation is a widely used screening modality for reflux, the use of descending venography provides the degree of detail and specificity that allows selection of candidates for deep venous valve repair or transplantation. These procedures are offered to patients with grade 3 or grade 4 reflux who have recurrent symptoms of venous insufficiency after treatment of superficial varicosities and perforating vein incompetence ( Table 28.2 ).