Dynamic monitoring of platelet deposition on severely damaged vessel wall in flowing blood. Effects of different stenoses on thrombus growth.

Abstract

The formation of an arterial thrombus Is a dynamic process that depends upon the characteristics of blood flow, the triggering substrate, and the blood components. We have developed and characterized a sensitive and specific computer-assisted nuclear sclntjgraphic method to study the dynamics of platelet deposition on severely damaged vessels both In vitro and in vivo In nonstenotlc and stenotlc flow conditions. Heparlnlzed pig blood with Indium-111 -labeled platelets was perfused for 50 minutes. Method variability In both static and flowing conditions was evaluated by Indlum-111-labeled transferrin and Indium-111 -labeled platelets. Positive scintlgrams were obtained mainly In the presence of severe high grade stenoses on a thrombogenlc substrate. Since the method is highly sensitive, computer-assisted axial dependence analysis was performed on the scintigraphlc Images to locate the thrombotic accumulation with respect to the area of the stenosis and to monitor the dynamic changes In platelet accumulation over time. Both In vitro and In vivo the highest level of platelet deposition occurred at the apex of the 80% stenosis, where ambollzation could be usually detected after 30 minutes of perfuslon. This study is the first to assess the dynamics of thrombus growth In nonparallel flow streamlines such as are encountered In stenotlc vessels. This method provides a new experimental tool with which to study factors affecting thrombus formation and stability.

Fluid mechanics of arterial stenosis: Relationship to the development of mural thrombus

“…Studies of blood flow through a stenosis using tunica media as a model for damaged vessel wall (2,16), or collagen-coated shunts, have shown increased platelet adhesion on the apex of a stenosis wherein fluid shear forces and shear-rate dependent diffusion are maximum. However, other studies did not show an increase in deposition with increased shear for noncollagencoated shunts (9), a decrease in platelet deposition onto a Lexan surface in the throat region of the stenosis supplemented by an increase in the downstream recirculation region (20), or a decreased deposition of plate-lets with increased flow rate through a hollow fiber hemodialyzer with canine and human blood (7).…”

In Vivo Dynamic Real-Time Monitoring and Quantification of Platelet-Thrombus Formation

“…19 We previously reported the use of a gamma camera and computer-assisted nuclear scintigraphy to dynamically monitor platelet deposition. 20 However, both methods are cumbersome and, therefore, not readily applicable to a clinical setting.…”

Current approaches to antithrombotic therapy in patients with cardioembolic stroke

“…Тромб создает внутриполостные неровности, ведущие к возникновению регионов повышенной турбулент-ности и последующему повышению режущей нагрузки, что способствует активации и агрегации тромбоцитов. Установле-но, что отложение тромбоцитов на резидуальном тромбе в 2-4 раза выше, чем на глубоко поврежденной сосудистой стенке [16]. Кроме того, фибрин-связанный тромбин, расположен-ный на поверхности резидуального тромба, подвергается дей-ствию циркулирующей крови, вызывая активацию как тромбо-цитов, так и каскадов коагуляции.…”