Electron microscopic evaluations of clot morphology during Thrombelastography®

In this study, we characterized clot morphology with a scanning electron microscope (SEM) at time points corresponding to the commonly used thrombelastography (TEG®) variables, illustrating the correlation of the physical clot formation with TEG® tracings. The first channel of the TEG® analyzer was used to obtain the tracings of clot formation, while the sub-samples for the SEM were obtained from the second TEG® channel. Different types of samples were examined, including whole blood, abciximab-treated whole blood, platelet-rich plasma (PRP), and abciximab-treated PRP. The SEM images were obtained at reaction time, different amplitudes (5-30 mm), maximum amplitude (MA), and at amplitude 60 min after MA. In the whole blood, coarse fibrin and activated platelets were observed at reaction time and fibrin strands progressively became more solid and intertwined at amplitude 10 mm and thereafter. Red blood cells were surrounded with fibrin strands at amplitude 30 mm and were tightly packed by fibrin strands at MA. In abciximab-treated whole blood, red blood cell shape was maintained at MA. The process of fibrin formation and platelet activation was also examined in PRP. Abciximab did not block platelet shape change, although the blockage of fibrin binding to platelets was shown on the TEG analyzer. In summary, we have shown structural changes of the forming clot in relation to TEG® variables.