Angiographic Investigation of Formation of Thrombi on Vascular Catheters

VASCULAR catheterization is widely employed in diagnostic technics (angiography' sampling of blood, and recording of blood pressure) and therapeutic methods (implants of artificial pacemakers and intravenous and intra–arterial drip infusions) . In diagnosis the catheter is seldom left in the vessel for more than a few hours, but in therapy it may remain in the vessel for up to several days. The most common serious complication of brief as well as of prolonged vascular catheterization is thromboembolism. Its frequency varies widely from series to series, e.g., frequencies of 1 per cent (11) and of 73 per cent (4) have been reported for prolonged catheterization of the inferior caval vein and 0 per cent (9) and 13 per cent (14) for the superior vena cava. Freyschuss (2) gives a figure of 1.9 per cent for arterial catheterization of four to six days duration. It has recently been shown (8) that the risk of thromboembolism varies with the area of the outer surface of the intravascular part of the catheter. This suggests that thrombus formation is stimulated by some reaction of the blood to the surface of the catheter. Subsequent in vitro experiments have shown that platelets adhere to the catheter and aggregate (5). Such a reaction is the initial step in the formation of thrombi (3, 12, 15) and presumably involves the risk of formation of thrombi on catheters placed in the blood stream. Using an isotope technic Jacobsson et al. have demonstrated in dogs (6) that platelets adhere to vascular catheters with the formation of thrombi as a result. On withdrawal of the catheter through the vessel wall, the thrombi were found to be wiped off, and thrombotic masses were formed at the site of the puncture. The discrepancies between the reported frequencies of thrombosis after vascular catheterization are probably due in large part to differences in the diagnostic criteria or in the capacity of the methods used. The objective of the present investigation was to obtain an angiographic estimate of the frequency and extent of thrombosis following vascular catheterization. Material And Methods Seven patients were selected at random, in whom an indwelling vascular catheter had remained for five to twenty–three days. In 4 a venous catheter had been inserted via a superficial arm or neck vein or the femoral vein, and in 3 patients an arterial catheter had been inserted via the femoral artery. Catheterized vessels, types of catheters, and clinical data are given in TABLE 1. The contrast medium was injected through the arterial catheters in patients with arterial catheterization; but the venographies were performed via a short catheter2 inserted into a peripheral vein.