Chronic Lower Extremity Venous Occlusive Disease

Venous thromboembolism—comprising pulmonary embolism and deep venous thrombosis (DVT)—is a common disease with a high recurrence rate. The incidence rates of venous thromboembolism in Western countries range from 8 to 27 per 10,000 person-years. The reported incidence of clinically diagnosed DVT is approximately twice that of pulmonary embolism. One of the most common complications of DVT is postthrombotic syndrome (PTS). PTS develops in 20% to 30% of patients with DVT within months after the initial diagnosis of DVT. Although PTS is not lethal, it reduces health-related quality of life and has important medical and socioeconomic consequences.

PTS refers to chronic venous insufficiency (CVI) resulting from DVT. CVI is reported to affect 11 million men and 22 million women between the ages of 40 and 80 years in the United States. CVI is a consequence of a combination of damaged valves of the veins leading to reflux, impaired circulation, and venous obstruction. The presence of reflux with or without venous obstruction can result in hemodynamic changes and venous hypertension. Inactivity, immobility, and abnormal gait also contribute to an ambulatory venous hypertension. In chronic venous hypertension the capillaries in the lower extremity become more permeable, leading to a leakage of plasma, proteins, and blood cells from the capillaries into the tissues. These changes are associated with the release of vasoactive substances from the endothelium, increased expression of adhesion molecules (E-selectin, ICAM-1), chemokines, and other inflammatory mediators, as well as damage to the endothelial glycocalyx. This eventually causes an increased inflammatory response, structural changes of the microvasculature, and reduced oxygenation of the skin and tissue. Changes in the skin and subcutaneous tissues include edema, varicose veins with trophic skin lesions, hyperpigmentation, purpura, varicose eczema, lipodermatosclerosis, atrophie blanche, and various stages of venous ulcers. The clinical symptoms from CVI include venous claudication, heaviness, and abnormal sensation.

Proximal iliofemoral venous thrombosis is the primary risk factor for the development of PTS. The iliofemoral vein is the most important outflow tract of the lower extremity. Because of the poor collateral potential, chronic occlusion in this segment results in a higher risk of PTS with more severe symptoms than occlusions in the lower venous segments, such as femoral, popliteal, and tibial veins. The current standard treatment for acute iliofemoral thrombosis consists of compression stockings, conventional systemic anticoagulation with low-molecular-weight heparin followed by oral warfarin, and mobilization. However, despite adequate anticoagulation, chronic changes of the iliac and femoral veins with partial or complete obstruction occur in up to half of the patients with DVT.

Recent advances in diagnostic imaging and endovascular techniques have allowed better management of chronic occlusive venous lesions related to PTS with a high technical success rate, effective symptom relief, low rate of procedure-related adverse events, and acceptable patency rates. Since the first description of endovascular recanalization with stent placement in 1992, the technique has been increasingly used and a number of studies have successfully demonstrated excellent results with large series of patients treated with balloon venoplasty and stenting of iliofemoral/iliocaval occlusive lesions.

Chronic occlusive venous disease can often be diagnosed based on the history and clinical symptoms. However, because of the nonspecific nature of clinical symptoms, color-flow duplex ultrasound is now the gold standard test. The lower extremity venous ultrasound examination is typically performed with the patient in reverse Trendelenburg position (elevation of the head in 10° to 20°). Lower abdominal and pelvic veins as well as infrainguinal veins, such as saphenous, popliteal, tibial, and gastrocnemial veins are included in the ultrasound examination. Although lower extremity veins can be evaluated with a high degree of accuracy, duplex ultrasound has its limitations in the assessment of inferior vena cava (IVC) and pelvic veins. Therefore contrast-enhanced computed tomographic or magnetic resonance venography (CTV, MRV) is essential to determine the extent of venous occlusion and to evaluate adequacy of inflow and outflow for interventional procedure. Conventional venography is typically only performed as a guide at the time of the intervention.

Air plethysmography (APG) is a noninvasive, functional test that continuously assesses real-time volumetric changes in the calf, provides physiologic quantitative information, and correlates with ambulatory venous pressure measurements. This test is performed with an air-inflated cuff around the calf that connects to a pressure transducer and recorder for detecting pressure changes resulting from variation in calf circumference. This is reported as a volume change in milliliters or a rate of volume reduction in milliliters per second (venous drainage index). In a healthy unobstructed leg, rapid venous emptying on elevation of the leg is a typical feature. In an obstructed leg, the venous drainage index is significantly decreased. Compared to duplex ultrasound, the APG device is more portable, less expensive, and easier to use. Given these advantages, APG may play an important role in the quantification of venous obstruction and hemodynamic screening before a percutaneous venous intervention.

Technique

Anatomy and Approach

A thorough knowledge of the normal anatomy and variations of the venous system in the lower extremity, pelvis, and abdomen is critical for a diagnosis and successful intervention. A comprehensive review of the preliminary venous imaging studies (ultrasound, MRV, CTV) is essential to determine whether the patient is a candidate for percutaneous intervention, as well as for procedural planning itself ( Fig. 69.1 ) . The popliteal vein is the most common access site for a percutaneous iliofemoral venous intervention. It is formed by the confluence of multiple small veins, such as the lesser saphenous vein, soleal vein, and gastrocnemial veins. The femoral vein drains the popliteal vein via direct connection in 38% of limbs and via tributaries in 48% of limbs. In the popliteal fossa, the popliteal vein is often superficial (closer to the posterior skin surface) to the artery, making percutaneous puncture more straightforward and safer.

Technical Aspects

Identification of Venous Access Site

As mentioned in the previous section, access to the venous system from the popliteal fossa is commonly performed. This approach allows easy antegrade venography and improved application of directional force to catheters and guidewires while traversing rigid occlusions. However, the access site should be the lowest patent venous segment below the occlusion. For popliteal venous access, the patient is placed in the prone position on the angiographic table. Ultrasound is used for a preliminary review of the venous anatomy of the popliteal fossa. Either the popliteal vein or, preferably, a more superficial vein that drains into the popliteal vein, such as the short saphenous vein, is identified and selected for access. It is preferable (when possible) to avoid direct puncture and subsequent injury to the popliteal vein itself. Access from a more superficial vein will also allow easier hemostasis after the procedure.

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