Thrombus formation on the catheters inserted in human pulmonary arteries, and its inhibition by anticoagulant and antiplatelet agents

Dynamic evaluation of thrombus formation on vascular catheters has been impossible because thrombi on a catheter are detached when it is taken out. We observed thrombus formation in vivo by using a vascular endoscopic system, and evaluated the inhibitory effects of heparin and antiplatelet agents. During cardiac catheterization a Barman balloon catheter was inserted in the pulmonary artery (PA). When the balloon was inflated and wedged in the main PA, 10-20ml of saline was flushed through to provide a visual field. Observations were done in 13 patients under systemic heparinization. Four of these patients were on antiplatelet agents. On the other hand, observations were done without systemic heparinization in seven patients three of whom were using antiplatelet agents. Fibrin thrombi could be seen in all 13 patients without antiplatelet agents within 6 minutes (5.22±0.14min), while in patients on antiplatelet agents, no thrombi were seen within 10 minutes. We conclude that fibrin thrombi may be formed on vascular catheters within 6min. Antiplatelet agents inhibited this early thrombus formation, while heparin did not.