Impact of altered venous hemodynamic conditions on the formation of platelet layers in thromboemboli

Bajd, Franci; Vidmar, Jernej; Fabjan, Andrej; Blinc, Aleš; Kralj, Eduard; Bizjak, Nina; Serša, Igor

doi:10.1016/j.thromres.2011.09.007

Cited by 24 publications

(24 citation statements)

References 24 publications

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“…Although we were not able to follow thrombus formation in patients in real time, TPLSM imaging of thrombi formed on CVCs removed from patients showed fibrin plaques that develop in a corresponding region containing flow eddies. Furthermore, the presence of circles and twisted layers in the fibrin plaque that we have observed by both SEM and TPLSM techniques, suggested the presence of eddy flow close to the hole rim . In this region, the fibers bifurcate, and alterations in the arrangement of the fibrin in the thrombi were observed also by TPLSM as reported in Fig.…”

Section: Discussionsupporting

confidence: 79%

“…The overall flow patterns within the vein and around the venous side holes contained regions of flow eddy and flow separation in both the obstructed and unobstructed catheter models. Previous studies reported that platelet aggregation preferentially occurs at regions of low shear stress, that is, in flow eddies and in flow separation regions . In the flow eddy zone, the wall shear stress has been reported to remain at a low level (0.0–1.0 Pa) throughout the cardiac cycle due to the reversed flow conditions .…”

Section: Discussionmentioning

confidence: 99%

“…Although arteriovenous fistulas are recommended as the preferred choice of vascular access for hemodialysis patients, many patients dialyze using central venous catheters (CVCs) . Catheters guide the venous blood toward the hemodialysis machine and return it to the venous system in a safe and reliable way . The residence time for a nontunneled catheter in the vein should theoretically not exceed 2 weeks .…”

mentioning

confidence: 99%

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Blood Flow in Hemodialysis Catheters: A Numerical Simulation and Microscopic Analysis of In Vivo‐Formed Fibrin

et al. 2013

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Although catheters with side holes allow high flow rate during hemodialysis, they also induce flow disturbances and create a critical hemodynamic environment that can favor fibrin deposition and thrombus formation. This study compared the blood flow and analyzed the influence of shear stress and shear rate in fibrin deposition and thrombus formation in nontunneled hemodialysis catheters with unobstructed side holes (unobstructed device) or with some side holes obstructed by blood thrombi (obstructed device). Computational fluid dynamics (CFD) was performed to simulate realistic blood flow under laminar and turbulent conditions. The results from the numerical simulations were compared with the fibrin distribution and thrombus architecture data obtained from scanning electron microscopy (SEM) and two photons laser scanning microscopy (TPLSM) on human thrombus formed in catheters removed from patients. CFD showed that regions of flow eddies and separation were mainly found in the venous holes region. TPLSM characterization of thrombi and fibrin structure in patient samples showed fibrin formations in accordance with simulated flux dynamics. Under laminar flow conditions, the wall shear stress close to border holes increased from 87.3±0.2 Pa in the unobstructed device to 176.2±0.5 Pa in the obstructed one. Under turbulent flow conditions, the shear stress increased by 47% when comparing the obstructed to the unobstructed catheter. The shear rates were generally higher than 5000/s and therefore sufficient to induce fibrin deposition. This findings were supported by SEM data documenting a preferential fibrin arrangement on side hole walls.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Blood Flow in Hemodialysis Catheters: A Numerical Simulation and Microscopic Analysis of In Vivo‐Formed Fibrin

et al. 2013

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“…21,22 One study showed that peak blood flow velocity in femoral vein was higher in re-canalized deep venous thrombus than that in healthy subjects and emphasized the eddy blood flow as a risk factor for VTE. 23 These highlight the importance of implementing supplementary means of enhancing blood flow in situations where prophylaxis against venous thromboembolism is necessary. Our study showed that electrostimulation seems to improve venous flow as effectively as external compression stockings or devices but without compromising arterial blood run-off to the distal lower extremity.…”

Section: Discussionmentioning

confidence: 99%

Potential role of electrostimulation in augmentation of venous blood flow after total knee replacement: A pilot study

et al. 2015

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“…12–18 While some of these numerical models include blood flow, none have considered disturbed flow, which is likely a critical component in the development of VTE, as venous valves induce eddies that both lead to the induction of TF and increase the residence time of locally produced clotting factors. 19–21 In this report, we expand upon a recently described numerical model that highlights the significance of surface reactions 18, 22 through the incorporation of disturbed flow induced by an open venous valve in the equilibrium phase of the valve cycle. We analyzed the degree and location of thrombin formation with respect to TF position and compare these results to the case of non-disturbed flow, when a valve is not present.…”

Section: Introductionmentioning

confidence: 99%

Simulated thrombin responses in venous valves

Dydek

Chaikof

2016

Journal of Vascular Surgery: Venous and Lymphatic Disorders

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Objective Venous thromboembolism frequently results in thrombi formation near or within the pocket of a venous valve as the result of recirculating hemodynamics, which has been largely attributed to hypoxia-induced tissue factor (TF) expression. Numerical models are now capable of assessing the spatiotemporal behavior of the TF initiated coagulation cascade under non-uniform hemodynamics. The aim of this study was to use such a numerical simulation to analyze the degree and location of thrombin formation with respect to tissue factor position in the presence of disturbed flow induced by an open venous valve. Method Thrombin formation was simulated using a computational model that captures the hemodynamics, kinetics and chemical transport of 22 biochemical species. Disturbed flow is described by the presence of a valve in the equilibrium phase of the valve cycle with leaflets in a fully open position. Three different positions of TF downstream of the valve opening were investigated. Results The critical amount of TF required to initiate a thrombotic response is reduced by up to 80% when positioned underneath the recirculating regions near the valve opening. Additionally, due to the increased surface area of the open valve cusp, in conjunction with recirculating hemodynamics, it was observed that thrombin is generated inside the valve pocket even when the exposed region of TF is downstream of the valve. Conclusions The presence of pro-thrombotic surface reactions, in conjunction with recirculating hemodynamics, provides an additional mechanism for thrombus formation in venous valves, which does not require direct damage or dysfunction to the valve itself.

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Impact of altered venous hemodynamic conditions on the formation of platelet layers in thromboemboli

Cited by 24 publications

References 24 publications

Blood Flow in Hemodialysis Catheters: A Numerical Simulation and Microscopic Analysis of In Vivo‐Formed Fibrin

Blood Flow in Hemodialysis Catheters: A Numerical Simulation and Microscopic Analysis of In Vivo‐Formed Fibrin

Potential role of electrostimulation in augmentation of venous blood flow after total knee replacement: A pilot study

Simulated thrombin responses in venous valves

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