indium-oxine and Graft-Occlusion--Vascular

The effects of a recently synthesized anti-platelet aggregation drug (E-5510) on platelet deposition in a knitted Dacron aortic graft underwent preliminary evaluation by In-111 oxime labeled platelet imaging. Seven patients undergoing aortofemoral bypass using this graft for occlusive disease were randomized into two groups: those receiving E-5510 and those receiving no medication. This agent was administered for 17 days postoperatively, and on the 14th day In-111 platelets were injected and images were acquired at 24, 48, and 72 hours. Platelet deposits in the grafts were assessed by the ratios of graft radioactivity to that of the adjacent native iliac arteries. Platelet deposition at the sites of anastomosis and deposition along the entire graft were normalized by initial deposition at 24 hours, and had significantly decreased at 72 hours in the three treated patients, while the normalized deposition increased progressively over time in the remaining four nonmedicated patients. E-5510 seems to have the potential to inhibit excessive platelet deposition on recently implanted grafts.

Topics: Aged; Aged, 80 and over; Aorta, Abdominal; Arterial Occlusive Diseases; Blood Vessel Prosthesis; Fatty Acids, Monounsaturated; Femoral Artery; Graft Occlusion, Vascular; Humans; Indium Radioisotopes; Male; Middle Aged; Organometallic Compounds; Oxyquinoline; Platelet Aggregation; Platelet Aggregation Inhibitors; Polyethylene Terephthalates; Radionuclide Imaging

Every effort to reduce synthetic graft infection is welcome and when designing antibiotic-bonded grafts it is important not to increase graft thrombogenicity. In order to study the acute thrombogenicity of rifampicin-soaked gelatin-sealed Dacron grafts compared with untreated gelatin-sealed Dacron grafts, an experimental carotid artery sheep model was used. Twenty sheep were anaesthetised and 7-cm-long 5-mm-wide externally supported gelatin-sealed knitted Dacron grafts were sutured end to end into each carotid artery after excising a portion of that vessel. Test grafts had previously been immersed for 15 min in a rifampicin solution (1 mg ml-1) while control grafts were immersed in physiological saline for 15 min. There were two groups with 10 sheep in each. In one group the blood flow through the grafts was unrestricted but in the second the flow was restricted to 25 ml min-1. Platelets from sheep labelled with 111In and sheep fibrinogen labelled with 125I were injected intravenously. The isotope activities were continuously measured proximally and distally over the grafts for 4 h. With unrestricted flow 4 out of 10 rifampicin-soaked grafts occluded compared with 2 out of 10 control grafts (N.S.). Time to occlusion, thrombus weight, platelet and fibrinogen activity did not differ. In the restricted flow group 9 out of 10 rifampicin-soaked grafts occluded compared with 6 out of 10 control grafts (N.S.). The time to occlusion did not differ. The thrombus weight in the rifampicin group was significantly higher compared with the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Blood Flow Velocity; Blood Vessel Prosthesis; Carotid Arteries; Female; Fibrinogen; Gelatin; Graft Occlusion, Vascular; Indium Radioisotopes; Iodine Radioisotopes; Male; Organometallic Compounds; Oxyquinoline; Platelet Adhesiveness; Polyethylene Terephthalates; Radionuclide Imaging; Rifampin

The patency of microvascular grafts depends on the luminal diameter, which is determined by the amount of fibrin and platelets deposited on the intraluminal surface and the anastomotic site, and the extent of pseudointimal formation. An experimental microvascular model in rats has been developed in our laboratory using Indium-111-labeled platelets to measure the amount of deposition on grafts inserted into the infrarenal aorta. This study was designed to assess the patency rates in these grafts and the pathologic maturation as determined by light and electron microscopy. Our study suggests that substantial patency rates can be achieved in aspirin-treated rats, although there was little influence on the pathologic maturation. Indium-111 oxine-labeled platelets can be used to document platelet aggregation, and the technique can be a valuable adjunct in the study of microvascular grafts.

Topics: Animals; Aorta, Abdominal; Aspirin; Blood Platelets; Blood Vessel Prosthesis; Graft Occlusion, Vascular; Indium Radioisotopes; Organometallic Compounds; Oxyquinoline; Polytetrafluoroethylene; Radionuclide Imaging; Rats; Vascular Patency

This study examined the effect of 9-beta-methyl carbacyclin, a synthetic, stable prostacyclin analog, on canine polytetrafluoroethylene (PTFE) graft patency. Twenty-five dogs had 4 mm x 7 cm PTFE grafts implanted bilaterally into the femoral arteries. A subcutaneous infusion pump was used to deliver either saline solution (control) or 9-beta-methyl carbacyclin (Ciprostine) at 100 (CARB-100) or 200 ng/kg/min (CARB-200) through a femoral artery branch just proximal to one of the femoral grafts, with the contralateral graft serving as a noninfused control. Graft-platelet deposition (with 111In-labeled platelets) was measured between the fifth and seventh days, with patency determined on the seventh day. Dogs were classified as aggregators (AGG [+]) if the preoperative epinephrine-enhanced sodium arachidonate platelet aggregation was greater than 20%. CARB-200 infusion significantly improved ipsilateral graft patency (80%) compared with noninfused grafts (50%, p less than 0.05), or grafts in control and CARB-100 dogs (43%, p less than 0.05). Anastomotic platelet deposition was decreased bilaterally in CARB-200 dogs by 45% to 59% compared with CARB-100 and control dogs (p less than 0.05). With the exception of grafts infused with CARB-200, AGG (+) dogs had significantly lower graft patency (26%) than nonaggregator AGG (-) dogs (71%, p less than 0.01). CARB-200 infusion significantly improved graft patency in AGG (+) dogs (71%), compared with control and CARB-100-infused grafts (19%, p less than 0.025). Intra-arterial 9-beta-methyl carbacyclin improved early PTFE graft patency and inhibited platelet deposition in a severe canine model, independent of baseline platelet aggregation status, which also had an important effect on graft patency.

Topics: Animals; Blood Vessel Prosthesis; Dogs; Epoprostenol; Female; Femoral Artery; Graft Occlusion, Vascular; Indium Radioisotopes; Infusion Pumps; Infusions, Intra-Arterial; Organometallic Compounds; Oxyquinoline; Platelet Aggregation; Polytetrafluoroethylene; Prostaglandins, Synthetic; Vascular Patency

Arterial grafts were studied with indium-III-labelled platelets in 13 patients (18 graft limbs) in the early post-implication period. Platelet thrombogenic activity was graded into four grades by visual inspection of the images, and scintigraphic criteria of impending graft occlusion were defined. Dacron and polytetrafluoroethylene grafts had similar high thrombogenic activity in comparison with autologous veins. Nine graft studies showed patterns of radioactivity concentration that suggested threatening thrombosis and eight of these eventually occluded. In nine other studies absent to moderate radiolabelled platelet activity was observed and none occluded within a mean follow-up period of 24 months. Prediction of graft occlusion of scintigraphic evaluation using the present simple non-invasive technique is valuable since corrective measures may be instituted earlier and with greater success in the post-operative follow-up period.

Topics: Aged; Aged, 80 and over; Blood Platelets; Blood Vessel Prosthesis; Female; Graft Occlusion, Vascular; Humans; Indium Radioisotopes; Male; Middle Aged; Organometallic Compounds; Oxyquinoline; Polyethylene Terephthalates; Polytetrafluoroethylene; Radionuclide Imaging; Saphenous Vein