Clinical Presentation

Patients with chronic vena cava occlusion develop networks of deep and superficial venous collaterals, which are unable to respond to hemodynamic demands of changes in posture or physical activity with the same efficiency of the large-caliber vena cava. In fact, some of these venous collaterals may be physically compromised when the patient bends over in the course of daily activities, such as to tie a shoe or retrieve something from the floor.

Patients with congenital vena cava occlusion often adopt sedentary lifestyles or preferences for entertainment and exercise that are compatible with their blunted venous return. Commonly the vena cava occlusion is so subtle in onset and gradual in development that the patient’s accommodation of physical limitations is imperceptible and must be elicited with specific questions during the clinical interview. Symptoms of superior vena cava occlusion such as fullness of the tongue or changes in color perception might only be recognized when they are suddenly relieved, following successful recanalization.

Generally, the entire constellation of symptoms is cumulatively a great burden to the patients, and most are eager for relief. The issue of elective recanalization of congenital IVC occlusion is less straightforward. Indications for treatment in our experience include need for IVC access, such as radiofrequency (RF) ablation for atrial fibrillation or relief of outflow obstruction in the setting of lower extremity DVT.

Imaging Evaluation

Cross-sectional imaging of the neck and chest in instances of SVC occlusion and of the abdomen and pelvis in instances of IVC occlusion should be a part of every elective recanalization. Intravenous contrast allows demonstration of every major vessel conducting hemodynamically significant blood flow and identifies the potential target inflow and outflow channels. Cross-sectional imaging also demonstrates areas of critical anatomy to be avoided during recanalization procedures, including the subclavian and innominate arteries in the upper chest; the aorta and right pulmonary artery near the cavoatrial junction; and the right renal artery, duodenum, and iliac arteries in the abdomen and pelvis. Cross-sectional imaging demonstrates venous segments containing contrast. Anatomically patent segments no longer conducting flow because of downstream occlusion and upstream collaterals may be overlooked. Transcutaneous ultrasound with compression is a valuable imaging adjunct in the groin and is useful for exploring the confluence of great saphenous, femoral, and deep femoral veins.

Vascular Access for Endovascular Treatment

Venous access for caval recanalization is achieved with ultrasound (US) guidance. In SVC recanalization, vascular access may be the internal jugular vein or one of the brachial veins, depending on the preoperative US studies. In general, collaterals between the axillary and jugular veins and between the two jugular veins are so profuse, recruitment of a single subclavian or internal jugular vein in continuity with the SVC generally provides significant relief of SVC syndrome. In IVC recanalization, sites of vascular access include the right internal jugular vein and bilateral great saphenous or common femoral veins. Occasionally, when an IVC thrombosis is continuous with iliofemoral thrombosis, access into the popliteal vein may be necessary.

The level of sedation depends on the anticipated discomfort and duration of the procedure. In the setting of acute-on-chronic occlusion, when the initial procedure consists of establishing venous access and initiating thrombolysis, the author generally uses moderate sedation. In procedures involving recanalization and often painful dilation of long segments of chronically occluded IVC or iliac veins, general anesthesia is used. Recanalization with stiff guidewires can perforate chronically thrombosed venous channels and create false passages. These can be left to thrombose while recanalization from the opposite direction is attempted using an alternate venous access. Once guidewire access across the occluded segment has been demonstrated to be acceptable, anticoagulation is administered.

Technique of Venous Recanalization

In cases of SVC occlusion, the author usually obtains venous access from the right internal jugular and right great saphenous veins. In patients with more extensive venous thrombosis, the choice among the internal jugular or brachial veins depends on the caliber of these veins as well as their proximity to the stump of SVC as demonstrated on preoperative imaging. In cases of IVC occlusion that extend to the iliocaval confluence, access is obtained from the right internal jugular and bilateral great saphenous veins.

The saphenous access offers several advantages over the common femoral vein, including a theoretically lower risk of significant postoperative bleeding in these patients, who are often aggressively anticoagulated, as well as allowing deployment of stents down to the saphenofemoral confluence. Even in cases of iliofemoral thrombosis, initial access into the greater saphenous vein is preferred over the popliteal vein. The former access route allows better control of catheters and guidewires when crossing occlusion of the iliac vein and IVC. Access is thus antegrade with the direction of blood flow, namely, from the saphenous access when treating the IVC or from the jugular access when treating the SVC. Contrast injections then fill adjacent segments of the vein to be recanalized or collaterals reconstituting either segments of the target vein farther downstream or nontarget channels to be avoided.

Contrast venography is performed after access has been obtained. This usually demonstrates multiple collaterals, which might or might not localize the thrombosed target vessel, depending on the site of injection, length of thrombosis, and point of recanalization. For this reason, it is usually best to start with an injection near the point of occlusion, with care not to advance the catheter into collaterals bypassing the obstruction. For example, in the cases of iliocaval occlusion, contrast injection at the saphenofemoral confluence will fill even the chronically thrombosed common femoral vein, as well as superficial body wall collaterals (Figure 1). The thrombosed target vein often appear as a threadlike channel, called a string sign, in the expected course of the iliac vein or IVC (see Figure 1). At this point, a catheter and guidewire are directed into the vein of choice.

In cases of chronic thrombosis, considerable resistance to advancement of the guidewire and catheter may be encountered, and the catheter might need to be buttressed with a sheath. In fact, if the catheter or guidewire move without resistance, one should suspect the catheter is in a collateral vein or has perforated the vein and is extravascular, either of which can be confirmed with a small contrast injection.

Uncomplicated recanalization proceeds by intermittent wire advancement, catheter passage, contrast injection to confirm intravenous location, and sheath advancement, all performed patiently and with a readiness to abandon pathways that do not look right or that repeatedly lead the catheter and wire into collateral pathways (Figure 2). In case of perforation of the thrombosed vessel wall and extravascular false passage of the catheter and wire, the catheter can be withdrawn until contrast injections reflux into venous structures, whereupon the catheter may be redirected and advanced by an alternative route. Occasionally, the thrombosed segment is so small or tight and the false passage is so prominent that attempts to redirect the catheter are fruitless. In these cases, it is best to retract the catheter into a confirmed intravascular location and attempt to complete recanalization from an alternate route.

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