The dynamics of platelet deposition on control polyurethane catheters (CPC) and heparin-bonded polyurethane catheters (HBPC) were evaluated with In-111 labeled platelets (In-PLT) using a computerized gamma camera (CGC). Ten nonheparinized dogs (18-25 kg) had both femoral arteries catherized with 10 cm of CPC and HBPC (5 Fr.) 24 hr postinjection of 300-420 microcuries of In-PLT, and imaged for 3 hr with a gamma camera. Regional platelet deposition on three segments of catheters and the puncture site was determined. Catheters were harvested and radioactivity on the catheter segments (proximal: PROX, middle: MID, distal: DIST and puncture site: PS) of both was determined. From the platelet count in blood, and radioactivity in blood and segments of catheters, adjacent artery, and area of artery and catheter, the platelet-density [X103 (mean ± S.D.)] on catheter and artery was calculated and tabulated. Proximal values were cath (CPC), 1289 ± 1125; artery, 1355 ± 587; cath (HBPC), 125 ± 113; artery, 1149 ± 1620. The middle values were cath (CPC), 1102 ± 1109; artery, 1512 ± 625; catg (HBPC), 132 ± 108; artery, 1011 ± 942. Cistal values were cath (CPC), 780 ± 584; artery, 132 ± 108; cath (HBPC), 227 ± 194; artery, 1457 ± 1309. The puncture site values were cath (CPC), 106 ± 382; artery, 1011 ± 942; cath (HBPC), 164 ± 135; artery, 1498 ± 1240. The large standard deviation in retained platelets is due to embolization. The platelet-density and regional counts on catheter segments were lower with HBPC than CPC, as was the rate of platelet-deposition. Most of the thrombi were lost during pull-out of the catheter. Both in vivo (dynamic) and in vitro studies were necessary for evaluation of CPC thrombogenicity.
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