PLATELET DEPOSITION AND PSEUDO-INTIMAL HYPERPLASIA IN PROSTHETIC VASCULAR GRAFTS

Platelet and fibrin accumulation in arterial grafts may cause pseudo-intimal hyperplasia and graft occlusion. The relationship between the rate of post-operative platelet accumulation and subsequent pseudo-intimal hyperplasia has been studied in prosthetic grafts implanted in greyhounds.The femoral artery in 30 greyhounds was replaced by a 6cm length of 6mm PTFE. Autologous 111In-platelet deposition over the graft was measured by probe and ratemeter for 7 days and radioactivity compared to the contralateral thigh. The daily increase in this ratio graft over reference was calculated as the Thrombogenicity Index (TI). Grafts were removed at 8 weeks and sectioned at 5, 30 and 55mm for measurement of pseudo-intimal thickening by grid microscopy.The animals subsequently developing occlusion or pseudo-intimal harrowing of greater than 50% of the lumen had a markedly greater TI of 0.22±0.027 compared to 0.03±0.019 in the 23 grafts maintaining wide patency (p<0.05). TI was highest in the 4 grafts which occluded at 0.3110.09 compared to 0.04±0.02 in the 26 that remained patent (p<0.01). There was a highly significant correlation (r=0.69) between post-operative TI and subsequent pseudo-intimal hyperplasia (p<0.001).Platelet deposition in the early post-operative period appears to promote the development of progressive pseudo-intimal thickening and ultimate occlusion

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PLATELET DEPOSITION AFTER CAROTID ENDARTERECTOMY DECREASES WITH TIME.

10.1055/s-0038-1643480 ◽

1987 ◽

Author(s):

A C Meek ◽

P Jarvis ◽

C M Backhouse ◽

CN McCollum ◽

RM Greenhalgh

Keyword(s):

Carotid Endarterectomy ◽

Intimal Hyperplasia ◽

Gamma Camera ◽

Contralateral Side ◽

Uptake Ratio ◽

Platelet Deposition ◽

Platelet Accumulation

Platelets are deposited on the exposed media following carotid endarterectomy and will continue to accumulate until neointima covers this thrombogenic surface. Radiolabelled platelet uptake was measured to assess the time to intimal repair.Autologous llllndium labelled platelets were infused 2 days and 2 months postoperatively in 10 patients undergoing unilateral carotid endarterectomy. Platelet accumulation was measured daily by gamma camera images counting radioactivity over the operated artery and comparing it to the contralateral side as Carotid Uptake Ratio (CUR).Mean (±sem) counts per gamma camera cell over the operated side at 24 hours were 46.3± 4.3 compared to 38.6± 3.9 on the unoperated side (p<0.001). At 2 months this difference had disappeared with counts of 38.8± 3.2 and 39.1± 3.2 over the operated and reference arteries respectively. Early postoperative CUR at 1.22± 0.04 was significantly higher than 1.01± 0.06 at 2 months which equates to no radiolabelled platelet uptake (p< 0.01). Radioiabellea platelet uptake was visible on 8 of the 10 early scans, but this was seen in only 2 patients at 2 months, both of whom had a persistently high CUR indicating continued platelet accumulation at that time.Early postoperative platelet deposition decreases in the weeks following carotid endarterectomy presumably due to the development of a neointima. Those cases with persistently high platelet accumulation may have luminal thrombus which could lead intimal hyperplasia and restenosis.

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Platelet Inhibitory Drugs: An In Vivo Method of Evaluation in Patients

Thrombosis and Haemostasis ◽

10.1055/s-0038-1657287 ◽

1982 ◽

Vol 48 (03) ◽

pp. 307-310 ◽

Cited By ~ 6

Author(s):

H C Norcott ◽

M Goldman ◽

R J Hawker ◽

E I Rafiqi ◽

Z Drolc ◽

...

Keyword(s):

Reference Site ◽

Arterial Grafts ◽

Prosthetic Materials ◽

Platelet Deposition ◽

Platelet Labelling ◽

The Mean ◽

Platelet Accumulation ◽

Method Of Evaluation

SummaryThe measurement of platelet deposition in human thrombi is essential for the evaluation of platelet-inhibitory drugs and prosthetic materials for use in patients. The rate of 111Indiumlabelled platelet accumulation on Dacron arterial grafts was measured in 27 patients randomised to take either aspirin and dipyridamole (ASA + DPM) or placebo. Autologous platelets were labelled and re-injected seven days following surgery and the graft thrombogenidty index calculated as the daily rise in the ratio of emissions from the graft over a reference site.The mean (± SD) thrombogenidty index in 12 patients undergoing femoro-popliteal bypass was 0.25 ± 0.09 on placebo and 0.16 ± 0.07 on ASA + DPM started pre-operatively (p Ã0.05). Post-operative ASA + DPM therapy started two days following platelet labelling in 15 patients with aorto-femoral grafts also significantly reduce thrombogenidty to 0.12 ± 0.05 compared with 0.25 ± 0.08 on placebo (p Ã0.01). In the latter patients the ratio of emissions from the graft over reference fell significantly on starting ASA + DPM, suggesting a net loss of platelets from the graft. These results indicate that the rate of in vivo platelet accumulation on Dacron grafts can be quantitated and that ASA + DPM reduced this rate in man.

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THE THROMBOGENICITY OF PTFE ARTERIAL GRAFTS INCREASES IN THE WEEKS FOLLOWING IMPLANTATION

10.1055/s-0038-1643087 ◽

1987 ◽

Author(s):

A Chidlow ◽

A C Meek ◽

I F Lane ◽

P Pate ◽

C N McCollum

Keyword(s):

Femoral Artery ◽

Bypass Grafts ◽

Arterial Grafts ◽

Flow Surface ◽

Risk Period ◽

Luminal Area ◽

Late Thrombosis ◽

Platelet Accumulation ◽

Discharge From Hospital ◽

Platelet Content

Despite few failures in the initial weeks, polytetrafluoro-ethylene (PTFE) femoro-popliteal grafts, which have a non-thrombogenic flow surface, frequently occlude between 2 and 6 months following implantation [1]. Radiolabelled platelet uptake was studied during this risk period.In 20 greyhounds, 6cm lengths of 6mm PTFE were implanted in the femoral artery and autologous 111In-platelet accumulation measured 1 and 8 weeks later. Radioactivity over the graft was compared to the contralateral thigh and the daily rise in this ratio expressed as the Thrombogenicity Index (TI). At 8 weeks the graft was excised, 111In-platelet content counted in a well crystal and pseudointimal hyperplasia measured by grid microscopy.Mean (± sem) TI of 0.054±0.02 at 1 week almost doubled in the grafts that remained patent at 8 weeks to 0.10±0.02 (p<0.05). Radioactivity on the excised grafts was 0.012±0.0027 percent of injected activity and this correlated closely with TI at 8 weeks (r=0.83, p<0.001). Even in grafts remaining patent, this late accumulation of radiolabelled platelets correlated closely (r=0.63, p<0.02) with pseudointimal hyperplasia which narrowed the graft by a mean of 18±4.7 percent of luminal area.PTFE grafts had a low initial thrombogenicity which increased by the second month. This rising thrombogenicity, which presumably follows luminal deposition of fibrin and platelets, is associated with pseudointimal hyperplasia which may explain why these grafts frequently occlude in the months following discharge from hospital.1. Veith FJ, Gupta S, Daly V. Management of early and late thrombosis of expanded PTFE femoro-popliteal bypass grafts. Surgery 1980; 87: 531-587.

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Platelet Accumulation on Fibrin-coated Polyethylene: Role of Platelet Activation and Factor XIII

Thrombosis and Haemostasis ◽

10.1055/s-0038-1653880 ◽

1995 ◽

Vol 73 (05) ◽

pp. 850-856 ◽

Cited By ~ 14

Author(s):

F D Rubens ◽

D W Perry ◽

M W C Hatton ◽

P D Bishop ◽

M A Packham ◽

...

Keyword(s):

Factor Xiii ◽

Cross Linking ◽

Internal Diameter ◽

Static System ◽

Graft Occlusion ◽

Platelet Binding ◽

Coated Surface ◽

Platelet Accumulation ◽

Polyethylene Tubing

SummaryPlatelet accumulation on small- and medium-calibre vascular grafts plays a significant role in graft occlusion. We examined platelet accumulation on the surface of fibrin-coated polyethylene tubing (internal diameter 0.17 cm) during 10 min of flow (l0ml/min) at high wall shear rate (764 s-1). Washed platelets labelled with 51Cr were resuspended in Tyrode solution containing albumin, apyrase and red blood cells (hematocrit 40%). When the thrombin that was used to form the fibrin-coated surface was inactivated with FPRCH2C1 before perfusion of the tubes with the platelet:red blood cell suspension, the accumulation of platelets was 59,840 ± 27,960 platelets per mm2, whereas accumulation on fibrin with residual active thrombin was 316,750 ± 32,560 platelets per mm2 (n = 4). When the fibrin on the surface was cross-linked by including recombinant factor XIII (rFXIII) in the fibrinogen solution used to prepare the fibrin-coated surface, platelet accumulation, after thrombin neutralization, was reduced by the cross-linking from 46,974 ± 9702 to 36,818 ± 7964 platelets per mm2 (n = 12, p <0.01). Platelet accumulation on tubes coated with D-dimer was ten times less than on tubes coated with D-domain; this finding also supports the observation that cross-linking of fibrin with the formation of γ-γ dimers reduces platelet accumulation on the fibrin-coated surface. Thrombin-activated platelets themselves were shown to cross-link fibrin when they had adhered to it during perfusion, or in a static system in which thrombin was used to form clots from FXIII-free fibrinogen in the presence of platelets. Thus, cross-linking of fibrin by FXIII in plasma or from platelets probably decreases the reactivity of the fibrin-containing thrombi to platelets by altering the lysine residue at or near the platelet-binding site of each of the γ-chains of the fibrinogen which was converted into the fibrin of these thrombi.

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Studies of Suloctidil in Experimental Thrombosis in Baboons

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661329 ◽

1985 ◽

Vol 53 (03) ◽

pp. 423-427 ◽

Cited By ~ 15

Author(s):

Stephen R Hanson ◽

Laurence A Harker

Keyword(s):

Oral Administration ◽

Thrombus Formation ◽

Vascular Grafts ◽

Scintillation Camera ◽

Control Data ◽

Experimental Thrombosis ◽

Arteriovenous Shunts ◽

Platelet Deposition ◽

Heparin Anticoagulation ◽

Antithrombotic Efficacy

SummarySuloctidil has been evaluated in the baboon for its antithrombotic efficacy using models of both acute and chronic arterial thrombogenesis. Acute thrombus formation was initiated by Dacron vascular grafts inserted as extension segments into chronic arteriovenous shunts. 111In-platelet deposition was measured by scintillation camera imaging for one hour. The results after oral administration of suloctidil (100 mg/kg/d in two divided doses) were not different from control studies. Moreover, concurrent heparin anticoagulation did not affect 111In-platelet deposition compared with control data. In contrast, ticlopidine (20 mg/ kg/d) significantly decreased platelet deposition that was reduced further by the addition of heparin.Chronic arterial-thromboembolism was initiated by segments of polyurethane (Biomer) cannula introduced into chronic arteriovenous shunts. Thrombus formation by the polyurethane cannula was measured as 111In-platelet turnover (corrected for removal of senescent platelets). Cannula platelet consumption was unaffected by suloctidil (20 mg/kg/d given in two divided doses for two days preceding and throughout the period of platelet survival measurement). In contrast, dipyridamole (10 mg/ kg/d) and sulfinpyrazone (100 mg/kg/d) completely interrupted cannula platelet consumption.We conclude that suloctidil probably has little or no effect on platelet-dependent thrombus formation.

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Successful case of direct puncture of a prosthetic bypass graft in endovascular treatment for long superficial artery chronic total occlusion: a case report

European Heart Journal - Case Reports ◽

10.1093/ehjcr/ytaa391 ◽

2020 ◽

Author(s):

Makoto Sugihara ◽

Yoko Ueda ◽

Yuiko Yano ◽

Shin-Ichiro Miura

Keyword(s):

Femoral Artery ◽

Chronic Total Occlusion ◽

Bypass Graft ◽

Common Femoral Artery ◽

Critical Limb Ischaemia ◽

Complete Revascularization ◽

Anastomotic Site ◽

Graft Occlusion ◽

Total Occlusion ◽

Direct Puncture

Abstract Background The access site for endovascular therapy (EVT) is often limited because of multi-vascular diseases. Prior lower limb bypass can potentially limit the availability of common femoral artery access when EVT is required. Case summary An 88-year-old woman who presented with non-healing ulceration in the dorsalis pedis of the left foot despite treatment for several months was admitted to our hospital. She had undergone axillo-bilateral femoral bypass surgery for right critical limb ischaemia 3 years previously. Ultrasound and contrast computed tomography demonstrated bypass graft occlusion, left superficial femoral artery (SFA)-popliteal artery long chronic total occlusion from the origin with severe calcification and severe stenosis in the bilateral common femoral artery close to the anastomotic site. EVT for the left SFA occlusion was necessary to save the left foot, but access sites for EVT were limited. We decided to puncture an occluded axillo-femoral prosthetic bypass graft. It is difficult to cross the wire with only an antegrade approach. Therefore, it was necessary to use a bi-directional approach with dorsalis pedis artery puncture and the Rendez-vous technique. Finally, angiogram demonstrated improved blood flow to the wound site, and haemostasis at the puncture site could be achieved by manual compression. The ulceration healed within a month. Discussion Direct puncture of a prosthetic bypass graft and additional techniques resulted in complete revascularization. Thus, direct puncture of a bypass graft could be a useful EVT strategy for patients with complex and extremely long chronic total occlusion.

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Assessment of Electrospun Pellethane-Based Scaffolds for Vascular Tissue Engineering

Materials ◽

10.3390/ma14133678 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3678

Author(s):

Vera Chernonosova ◽

Alexandr Gostev ◽

Ivan Murashov ◽

Boris Chelobanov ◽

Andrey Karpenko ◽

...

Keyword(s):

Vascular Tissue ◽

Ex Vivo ◽

Vascular Grafts ◽

Wistar Rat ◽

Graft Occlusion ◽

Suitable Candidate ◽

Large Animals ◽

Cell Adhesion And Proliferation

We examined the physicochemical properties and the biocompatibility and hemocompatibility of electrospun 3D matrices produced using polyurethane Pellethane 2363-80A (Pel-80A) blends Pel-80A with gelatin or/and bivalirudin. Two layers of vascular grafts of 1.8 mm in diameter were manufactured and studied for hemocompatibility ex vivo and functioning in the infrarenal position of Wistar rat abdominal aorta in vivo (n = 18). Expanded polytetrafluoroethylene (ePTFE) vascular grafts of similar diameter were implanted as a control (n = 18). Scaffolds produced from Pel-80A with Gel showed high stiffness with a long proportional limit and limited influence of wetting on mechanical characteristics. The electrospun matrices with gelatin have moderate capacity to support cell adhesion and proliferation (~30–47%), whereas vascular grafts with bivalirudin in the inner layer have good hemocompatibility ex vivo. The introduction of bivalirudin into grafts inhibited platelet adhesion and does not lead to a change hemolysis and D-dimers concentration. Study in vivo indicates the advantages of Pel-80A grafts over ePTFE in terms of graft occlusion, calcification level, and blood velocity after 6 months of implantation. The thickness of neointima in Pel-80A–based grafts stabilizes after three months (41.84 ± 20.21 µm) and does not increase until six months, demonstrating potential for long-term functioning without stenosis and as a suitable candidate for subsequent preclinical studies in large animals.

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