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Asme05 ibis


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Asme05 ibis

  1. 1. In-vivo assessment of the relationshipIn-vivo assessment of the relationship between shear stress and plaquebetween shear stress and plaque vulnerability in human coronary arteriesvulnerability in human coronary arteries Frank Gijsen, Jolanda Wentzel, Attila Thury, Frits Mastik, Johannes Schaar, Johan Schuurbiers, Pim de Feyter, Ton van der Steen, Patrick Serruys, and Cornelis Slager Hemodynamics Lab, Department of Biomedical Engineering Erasmus Medical Center, Rotterdam, The Netherlands
  2. 2. Shear stress and atherosclerosis Shear stress has a strong impact on endothelial function. In the presence of risk factors, low shear stress is one of the key factors in localizing early atherosclerosis. Shear stress regulated compensatory remodelling prevents plaque protrusion into the lumen in early atherosclerosis. A subset of plaques might develop into vulnerable plaques. Vanderlaan, ATVB 2004
  3. 3. Shear stress and atherosclerosis cap lipid core high shear stress low shear stress flow
  4. 4. Slager et al., Nature Clinical Practice, in press.
  5. 5. Shear stress and atherosclerosisShear stress and atherosclerosis Aim: Investigate, in coronary arteries of patients, the relationship between shear stress and a marker of plaque vulnerability. Working hypothesis: Early atherosclerosis: low shear stress is one of the localizing factors of the disease and high shear stress acts protective. Advanced atherosclerosis: high shear stress, through its anti- inflammatory impact on the endothelium, might enhance plaque vulnerability.
  6. 6. MethodsMethods Shear stress: 3D lumen and wall data from ANGUS (biplane ANGiography and IVUS) combined with Computational Fluid Dynamics, using patient-specific flow and viscosity data. Strain data: IVUS based data palpography data render radial strain map at lumen wall. Problem (or challenge): match ANGUS (CVIS) with palpography data (Volcano) using anatomical landmarks.
  7. 7. ANGUS  3D wall thickness ANGUS + CFD  3D shear stress ANGUS + palpo  3D strain data high low
  8. 8. midcap upstream shoulder shoulder downstream flow Scoring system for shear stress and strain: 1: high 0: average -1: low Patient population: 10 patients 21 segments 22 plaques MethodsMethods
  9. 9. Results: shear stressResults: shear stress 1 0 -1 downstream 15 1 0 -1 shoulders 14 8 1 0 -1 midcap 11 5 1 1 0 -1 upstream 1 87 u s m d 0.38 0.64 0.59 -1.00
  10. 10. Results: shear stressResults: shear stress 0.31 0.55 0.12 -0.47 u s m d 1 0 -1 downstream 9 42 1 0 -1 shoulders 12 10 1 0 -1 upstream 8 5 3 1 0 -1 midcap 4 11 2
  11. 11. ResultsResults u s m d meanstrain p < 0.01 p < 0.01 meanshearstress 0.38 0.64 0.59 -1.00 p = 0.07 0.31 0.55 0.12 -0.47
  12. 12. ResultsResults NS p < 0.01 meanstrain shear stress -1 0 1 0.47 0.19 -0.41
  13. 13. Discussion and conclusions Low shear stress downstream of a plaque relates to low strain. Location alone cannot predict where we can find high shear stress and high strain. High shear stress predicts the location of high strain spots, confirming the hypothesis that high shear stress is related to plaque vulnerability. Follow-up data have to reveal if this relationship is confirmed.
  14. 14. Methods: matchingMethods: matching Volcano data CVIS data
  15. 15. Methods: ANGUSMethods: ANGUS lumen surface wall surface 3D catheter path from biplane angiography lumen and wall from IVUS
  16. 16. Methods: palpographyMethods: palpography   SOFT HARD Palpography determines radial strain from RF data as a measure for properties of tissue