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Shear stress and plaque composition (intravascular)

Shear stress and plaque location, progression and composition in coronary arteries in vivo using intravascular imaging

Investigators: Jolanda WentzelFrank Gijsen, Ayla Hoogendoorn, Annette Kok, Eline Hartman 

 

 

Background  

3D coronary artery geometry with mapped shear stress and IVUS cross sectionsAtherosclerotic plaques are found at particular places in the cardiovascular system for instance in the inner curve of arteries or close to side branches. These are the locations were the blood flow induced wall shear stress is low. Although some studies had investigated the relationship between shear stress and plaque localization in vitro or ex vivo before, we were the first that showed the relationship in h uman coronary arteries in vivo (Krams et al. ATVB 1997, Wentzel et al, circ 2003). For those studies the 3D reconstruction technique ANGUS, which combines biplane angiography and intravascular ultrasound (IVUS) technique was used together with computational fluid mechanics. Similar techniques were applied to investigate the relationship between shear stress and in-stent restenosis in bare metal stents (Wentzel et al, circulation 2000) and drug eluting stents (Gijsen et al, Am J Cardiol, 2003).

 

As shear stress is highly involved in numerous vascular biological processes, we also investigate the influence of shear stress in a more advanced stage of the disease. In this advanced stage of the disease plaque is often narrowing the lumen, resulting in exposure of the plaque to high shear stress. Evidence is accumulating for a role of high shear stress in plaque destabilization.In human coronary plaques we investigated the relationship between high shear stress and strain, a surrogate for the vulnerability of the plaque. This study confirmed that high strain spots, supposedly the plaque locations with more macrophages and thin fibrous cap, were exposed to high shear stress (Gijsen et al. Am J Physiol, 2008) and thus high shear stress potentially influences plaque destabilization. Follow up studies need to be performed to confirm the role of high shear stress in plaque destabilization.

 

Currently, we are studying the, in coronary arteries of patients and an atherosclerotic pig model, the relationship between shear stress and plaque composition over time. The advent of new catheter based systems that allow visualization of the plaque constituents, opened avenues for such studies. Intravascular ultrasound combined with near-infrared-spectroscopy (NIRS-IVUS) allows to map the presence of lipid rich plaque on the cross-sectional information of the IVUS image. Optical coherence tomography can visualize not only the presence of lipids and calcium but also the fibrous cap thickness.