Central vein catheter complications. A, This radiograph demonstrates the tip of this dialysis catheter abutting the wall of the left innominate vein at its junction with the superior vena cava. To maintain adequate dialysis flow rates and minimize fibrin sheath formation, it is important for the catheter tip to be in the superior vena cava, near or in the right atrium. B and C, Injection of contrast through these dialysis catheters demonstrates the contrast outlining the outside of the distal portion of the catheter (arrows). This finding is characteristic of a fibrin sheath with contrast medium trapped between the fibrin sheath and the outer wall of the catheter. Fibrin sheaths are associated with a reduction (often severe) in the achievable blood flow rate and, as a result, inadequate dialysis delivery. They can be lysed by instilling large doses of urokinase (typically 250,000 units) through the catheter ports. If thrombolytic therapy is unsuccessful, the fibrin sheath can be stripped using a snare loop. Although these catheters can function remarkably well, they are prone to thrombosis.
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D, The clot is typical of one that is remarkably tenacious. Before replacement of this catheter, a variety of manipulations were performed, including attempted thrombolysis with localized infusion of urokinase. A new catheter was placed in the same site in a same-day procedure using local anesthesia.
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