Catheter Related Subclavian Vein Thrombosis

David A. Bader MD

A. Van den Abbeele MD

May 16, 1995

Case Presentation:

A 54 year old female with breast cancer had a double lumen left subclavian portacath in place. Two weeks after the most recent cycle of chemotherapy (Adriamycin based) she developed local pain in the left upper chest at the time of chemotherapy. Minimal resistance to injection was reported by the oncology nurse. At the time of presentation there was some slight left neck swelling. A catheter flow study was requested.

Findings:

Portacath injection (23k bytes) demonstrated transit of activity in the catheter along the course of the left subclavian vein with abrupt termination at the level of the distal subclavian vein (arrow, 122k bytes). There was subsequent retrograde transit of activity into the tubing accessing the lateral port of the double lumen catheter (arrow heads) as well as appearance of activity around the periphery of the subcutaneous port indicating infiltration.

Peripheral left injection shows multiple collateral vessels coursing from the left axillosubclavian across the base of the neck, in the expected location of the jugular venous arch, with subsequent visualization of the SVC.

Peripheral right arm injection showed normal passage of activity through the axillosubclavian system through the SVC to the right heart. Persistent activity in the distal subclavian portion of the left subclavian catheter was noted (thin arrow).

Follow up study (14k bytes) again showed normal flow from the right arm and improved flow through the left subclavian region (the images from two left arm injections are combined with the camera position somewhat higher on the second injection).

Imaging Technique

Tc-99m Pertechnetate was utilized in 3 separate 10 mCi (370 MBq) injections. Both ports of the central line were accessed as were veins in the antecubital fossae bilaterally. Continuous dynamic acquisition at 1 frame/sec was utilized. Sequential injections of the medial port of the catheter, right arm, and left arm were performed with imaging centered over the upper chest.

Comparison Images

A study (27k bytes) from another patient shows normal flow through the left arm and through both ports of a portacath. A study from a third patient show normal flow through a catheter in the right subclavian vein, but multiple collaterals after injection of both arms simultaneously.

Discussion:

Thrombosis of the axillosubclavian venous system may be primary or secondary. Primary thrombosis has been referred to as idiopathic, spontaneous, or effort induced. Primary thrombosis, that of indeterminate cause, has also been termed "thoracic inlet syndrome". There are multiple causes for secondary thrombosis, all of which may be attributed to factors underlying Virchow's triad of venous stasis, vessel injury, and hypercoaguability. Iatrogenic trauma is an increasingly frequent cause due to subclavian venous catheterization. This complication is more common and less innocuous than previously realized (Reed).

In the past 2 decades there has been both increased use of central venous catheters as well as more widespread use of anticoagulation therapy. One large non-selected autopsy study has demonstrated a statistically significant increase in isolated thrombosis of the upper venous system from 6.7% of all deep venous thrombosis (DVT) in 1975 to 11.0% in 1987 (Diebold). This same study discussed a change in the principal location of venous thrombi with internal jugular venous thrombosis being the 2nd most frequent site in 1987-1988, 3d in 1975-1980, 11th in 1961-1963, and 12th in 1905 (Diebold). Total DVT from 1975 to 1987 increased from 27.6% to 34.9% in the group studied with a significant decline in the overall rate of fatal pulmonary embolism. The authors concluded that these findings provided evidence for a contributing role of venous catheterization in the increasing incidence of upper extremity thrombosis as well as evidence for DVT prophylaxis decreasing the incidence of fatal pulmonary embolism in the same period

The likelihood of thrombosis increases with multiple factors, including

Catheter materials vary in thrombogenicity with polyethylene being the most thrombogenic and silicone and polyurethane significantly less so (Pottecher). Whatever catheter is utilized, there is a near universal incidence of fibrin sheath formation (Hoshal, Pottecher). It has been demonstrated that within 5-7 days the entire length of the catheter will be circumferentially encased in fibrin (Hoshal). The significance of fibrin sheath formation is unclear although some regard it as a pre-thrombotic state (Pottecher). Persistent focal activity at the tip of the catheter on a radionuclide flow study is consistent with, but not specific for, fibrin sheath formation. Clinically it may present as resistance to injection or inability to withdraw blood.

Potential complications of catheter-related thrombosis include

It is estimated that 13-35% of patients with subclavian catheters will develop axillosubclavian vein thrombosis (Reed). A summary of 9 prospective trials performed from 1968 to 1987 demonstrated a 28% incidence of catheter related thrombosis (Horattas). Conversely, catheterization is estimated to account for 39% of all subclavian vein thrombosis. Pulmonary embolism occurs in 9-25% of these cases with a fatal embolic rate of 10% of all pulmonary embolism (Reed, Horattas).

Diagnostic Methods

The diagnosis of subclavian thrombosis has been historically made by standard contrast venography. However, it is invasive and expensive. Doppler studies, although excellent for the lower extremities, may be falsely negative in as many as 2/3 of cases in the axillosubclavian system in the presence of collaterals (Horattas). Impedance plethesmography is unreliable in the upper extremity and magnetic resonance venography is promising but at the present time is expensive and not universally available. Findings may be incidentally seen on CT scanning, particularly during evaluation of a known mediastinal mass, but it is not a primary modality for venous thrombus evaluation.

Nuclear medicine flow studies provide a relatively inexpensive, rapid, non-invasive method for screening. Tc-99m Pertechnetate is commonly utilized although tagged red blood cell venography has been described as a potentially useful alternative (Silverstein). Although nuclear medicine studies lack the spatial resolution of contrast venography, the major and minor collateral pathways to the SVC have been well demonstrated (Muramatsu). The five major systems that comprise the collateral venous network of the thorax include

The 5 systems interconnect to form a vascular loop that serves to maintain venous stability (Chasen).

Therapy

There is no firm consensus on the therapy for catheter-related thrombosis. Anticoagulation has been the mainstay of therapy with the premise of preventing clot propagation and allowing for collateral formation. However, the existing thrombus usually does not resolve completely and most cases would spontaneously improve without therapy . The sequelae of chronic post-phlebitic syndrome and pulmonary embolism are not necessarily prevented. Fibrinolytic therapy can potentially prevent delayed morbidity and can be performed without removal of the central venous catheter (Reed).

Conclusions:

Secondary subclavian vein thrombosis due to catheterization is more common and less innocuous than once thought. Radionuclide flow studies provide a rapid, non-invasive, and relatively inexpensive method for screening for venous thrombosis and catheter dysfunction. Standard anticoagulation therapy may not prevent delayed morbidity from chronic post-phlebitic syndrome and pulmonary embolism. Fibrinolytic therapy may prevent these complications and preserve the venous access site. It's future role in catheter management remains to be determined.

References:

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J. Anthony Parker, MD PhD, Tony_Parker@bih.harvard.edu