Vascular Compression Syndromes

Clinical Presentation

Paget-Schroetter syndrome (axillosubclavian vein thrombosis or “effort” thrombosis) usually presents with acute unilateral upper extremity swelling in a previously healthy patient, which often prompts urgent medical care. Archetypically, the patient is a young athlete or worker with a component to his or her sport or job that requires prolonged or repetitive stressful positioning of the arm, such as baseball pitchers, swimmers, weight lifters, volleyball players, and mechanics.

The involved extremity becomes acutely swollen with varying degrees of discoloration ranging from rubor to cyanosis. Physical examination may reveal the presence of dilated collateral veins around the shoulder and upper arm. The remainder of the physical examination is usually normal. If the condition is ignored, the symptoms may resolve when at rest but can either persist or recur with use of the arm, particularly in a stressed (abducted, externally rotated) position. The collateral channels that develop to allow the swelling to abate when at rest are rarely adequate to accommodate the increased venous return that occurs with activity.

Pathophysiology

The subclavian vein is subject to injury as it passes through the aperture formed between the first rib and clavicle. Anatomical studies have documented positional compression of the subclavian vein by the clavicle, subclavius muscle, and first rib ( Fig. 63.1 ). This can result in intrinsic damage and external scar that contributes to the stenosis and/or occlusion of the subclavian vein.

Diagnosis

History and physical generally suggest the diagnosis due to the sudden spontaneous onset of unilateral upper extremity swelling and discoloration. Duplex ultrasound has been advocated as the first step to diagnose venous TOS. However, duplex ultrasound has a false-negative rate as high as 30%, due to the interference of the clavicle with the acoustic window of the subclavian vein, so it cannot be used to exclude venous TOS.

Contrast-enhanced computed tomography (CT) or magnetic resonance (MR) venography are highly accurate in detecting axillary- subclavian vein occlusion and/or focal stenosis at the level of the first rib ( Fig. 63.2 ). They can be performed with the arms at rest and elevated to determine positional subclavian vein obstruction. They can also identify enlarged collateral veins and the chronicity of any thrombus present. Because these studies provide more anatomical information than venous duplex imaging, CT or MR venography can be used to accurately exclude the diagnosis of venous TOS when ultrasound studies are negative.

The optimal method to both diagnose and initially treat venous TOS is catheter-directed contrast venography. This provides complete anatomical information regarding the site and extent of thrombosis, allows definitive evaluation of the collateral venous pathways, and allows use of thrombolytic therapy. Catheter-based upper extremity venography is the most practical, efficient, and cost-effective approach to evaluating the patient with suspected subclavian vein effort thrombosis.

Treatment

The primary goals of therapy for venous TOS are to return the patient to unrestricted use of the affected extremity with complete symptom relief and freedom from recurrent thrombosis without the need for lifelong anticoagulation. Initial management should be catheter-directed venography and thrombolysis. Pharmacomechanical thrombolysis can reduce the clot burden rapidly, usually within a 1- to 2-hour session. An alternative is continuous infusion of thrombolytic agent over 24 to 48 hours with monitoring in an intensive care unit setting. Balloon angioplasty does not provide a durable benefit and placement of stents is contraindicated due to complications of frequent stent fracture. The patient is subsequently maintained on systemic anticoagulation until he undergoes surgery.

In patients with a satisfactory result after thrombolysis, surgical treatment is recommended within 4 to 6 weeks after presentation to avoid recurrent thrombosis of the subclavian vein. This time period does allow for some resolution of perivenous inflammation caused by the thrombotic event. Surgery can be safely performed sooner if the patient continues to have marked subclavian vein stenosis or occlusion after lysis.

There are several approaches to surgical decompression in venous TOS. However, over a two-decade experience, we have concluded that the paraclavicular approach to venous TOS appears to provide the safest and most effective management of this condition. All patients with venous TOS undergo surgical treatment using a combination of supraclavicular and infraclavicular incisions. Using the supraclavicular incision, resection of the anterior and middle scalene muscles is completed and the posterior first rib is transected at the transverse process. Using the infraclavicular incision, the rib is transected at the edge of the sternum anteriorly and removed. The subclavius muscle is also removed. This facilitates a complete external venolysis from the axillary vein to the junction of the subclavian, internal jugular, and innominate veins via the two incisions. Frequently, external venolysis is sufficient if complete resection of fibrous scar tissue allows the vein to resume its normal diameter and a widely patent subclavian vein with no significant collaterals is seen on venography. Residual vein stenosis or occlusion can be repaired with patch angioplasty or interposition vein bypass. Other approaches include the infraclavicular and transaxillary protocols of treatment of venous TOS. These have been shown to have disadvantages, chiefly relating to the lack of exposure of the vein for a complete venolysis and comprehensive treatment.

Outcomes

A recent review by Vemuri et al. demonstrates the results of surgical management of venous TOS. The paraclavicular approach is associated with greater number of vein bypasses and a longer length of stay. However, satisfactory clinical outcomes were greater with the paraclavicular approach, and the likelihood of remaining on long-term anticoagulation is markedly lower, at less than 5%.

Clinical Presentation

Arterial TOS is the most rare and varied form of TOS. Compression of the subclavian artery over time leads to progressive inflammation and scarring. This can be associated with poststenotic dilatation, which may progress to aneurysmal degeneration. Patients can present with intermittent claudication or rest pain of the upper extremity. In more severe forms, arterial TOS can be associated with gangrene of the hand or posterior stroke. Some patients are asymptomatic but have dilation of the subclavian artery noted incidentally during unrelated imaging investigations. A high degree of suspicion is warranted because presentation is so variable.

Pathophysiology

Bony abnormalities are typically seen with arterial TOS. Cervical ribs are associated with the majority of these cases. When the cervical rib projects from the transverse process onto the first rib, it displaces the brachial plexus and subclavian artery forward. In this location the subclavian artery is subject to an increased risk for compression or injury ( Fig. 63.3 ). Another common bony anomaly is the presence of an elongated C7 transverse process that acts in a similar fashion. Fibrous bands, if present, from the C7 transverse process to the first rib, can exacerbate compression. Clavicle or first rib fractures are also associated with arterial TOS.

Diagnosis

The diagnosis of arterial TOS can be suggested by the history and physical examination (see Chapter 11 ). Noninvasive vascular studies can be used to confirm a clinical impression of arterial insufficiency. Diagnostic studies including CT, MR, and catheter-directed arteriography have been used successfully to confirm the presence of arterial TOS. Following the diagnosis of arterial TOS, patients are maintained on systemic anticoagulation until surgery.

Treatment

Patients undergo thoracic outlet decompression from a supraclavicular approach. Sometimes, a second infraclavicular incision is also required. During decompression, the bony abnormality is generally encountered and resected. The artery is then inspected. The subsequent management modalities include observation, endarterectomy and patch, or bypass with either vein or Dacron.

Outcomes

Arterial TOS is very rare, thus most literature regarding this condition is case reports or series. In the largest series of 40 patients with a follow-up of nearly 5 years, 92% continued to have a patent subclavian artery. There were two reoperations. Chronic symptoms persisted in 15% of patients; these patients had long-standing ischemia prior to intervention. Functionality as measured by the Disabilities of the Arm, Shoulder and Hand (DASH) assessment was improved by nearly 50% in most of the patients. Overall, surgical management of this rare disease entity results in satisfactory outcomes when patients are referred promptly after symptoms ensue.