Platelet deposition on Dacron aortic bifurcation grafts in man: quantitation with indium-111 platelet imaging.
Authors: J R Stratton, B L Thiele, J L Ritchie
Journal: Circulation (1982)

The interaction between platelets and chronically implanted prosthetic arterial graft sur- faces in man was assessed by imaging indium-111-labeled platelet deposition in 15 patients with Dacron aortic bifurcation grafts.Grafts had been in place for 9-120 months.These results were compared with those obtained by platelet imaging of the aortofemoral vessels of 13 normal young adults without grafts.Quantitative evaluation was performed in both groups by a graft/blood ratio that compared indium-111 platelet activity in the aortofemoral vascular region to whole blood platelet activity over a 96-hour imaging time.In addition, blinded qualitative visual interpretation was performed on all studies by comparing aortofemoral area activity with that in adjacent native arteries.The reproducibility of the technique was evaluated by repeat imaging and quantitative analysis of six patients with grafts.Quantitative evaluation of the normal subjects revealed that the mean vessel/whole blood activity ratio was 2.0 ± 0.7 ( ± SD) at 24 hours after platelet injection and remained constant for the duration of the study (1.7 ± 0.9 at 96 hours, NS).In contrast, patients with grafts had a mean graft/blood ratio of 3.0 ± 1.6 at 24 hours, which increased progressively to 7.8 + 5.0 at 96 hours (p < 0.001 vs normal subjects), documenting ongoing platelet deposition in patients with vascular grafts.Independent qualitative visual interpretation of the aortofemoral region disclosed no abnormal uptake in normal subjects, whereas 13 of 15 patients (87%) with grafts had platelet deposition.The six reproducibility studies in patients with grafts were quantitative- ly unchanged and remained visually positive.Platelet deposition in chronically implanted Dacron arterial grafts was consistently present, progressive over 96 hours, quantifiable and reproducible.These results imply absent or incomplete endothelial cell coverage of the graft flow surface.The techniques described may be useful in assessing prosthetic material thrombogenicity and the efficacy of platelet-inhibitory drugs in man.THROMBOSIS and thromboembolism are well recog- nized complications of intravascular prostheses.Inad- equate measures for assessing prosthetic thrombogenicity in man have impeded the development of improved materials.' The finding that selective platelet consumption, without associated fibrinogen consump- tion, occurs in patients with recently implanted Dacron aortofemoral grafts,2 arteriovenous shunts3 and pros- thetic cardiac valves3 ' is indirect evidence that platelets have a predominant role in the thrombotic response to arterial prostheses.This conclusion is also support- ed by the finding of platelet deposition on recently implanted prosthetic grafts in baboons,2 rats5 and dogs.6-However, the detection of platelet deposition on chronically implanted grafts in animals6 8-10 or man9' 11-5 has been uncommon.Coverage of the graft flow surface with endothelial cells in experimental animals decreases both platelet deposition and the thrombotic and embolic complications of arterial prostheses.Progressive and complete endothelial cell coverage of short Dacron grafts occurs rapidly after implantation.2'&i0. 16. 17 In baboons, the progressive increase in endothelial coverage was asso- ciated with normalization of platelet survival over a 6- week period.2However, the cellular changes occurring