In-vivo assessment of the relationship In-vivo assessment of the relationship between shear stress and plaque between shear stress and plaque

vulnerability in human coronary arteriesvulnerability in human coronary arteriesFrank 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

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

Shear stress and atherosclerosis

cap

lipid core

high shear stress

low shear stress

flow

Slager et al., Nature Clinical Practice, in press.

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.

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.

ANGUS 3D wall thickness

ANGUS + CFD 3D shear stress

ANGUS + palpo 3D strain data

high

low

midcap

upstream

shouldershoulder

downstream

flow

Scoring system for shear stress and strain: 1: high 0: average-1: low

Patient population:

10 patients21 segments22 plaques

MethodsMethods

Results: shear stressResults: shear stress

1 0 -1

downstream15

1 0 -1

shoulders14

8

1 0 -1

midcap

11

51

1 0 -1

upstream

1

87

u s m d

0.38

0.64 0.59

-1.00

Results: shear stressResults: shear stress

0.31

0.550.12

-0.47 u s m d

1 0 -1

downstream

9

42

1 0 -1

shoulders

1210

1 0 -1

upstream

8

53

1 0 -1

midcap

4

11

2

ResultsResults u s m d

mea

n st

rain

p < 0.01

p < 0.01

mea

n sh

ear s

tress

0.38

0.64 0.59

-1.00

p = 0.07

0.31

0.55

0.12

-0.47

ResultsResults

NS

p < 0.01

mea

n st

rain

shear stress

-1 0 1

0.47

0.19

-0.41

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.

Methods: matchingMethods: matching

Volcano data

CVIS data

Methods: ANGUSMethods: ANGUS

lumen surface wall surface

3D catheter path from biplane angiography

lumen and wall from IVUS

Methods: palpographyMethods: palpography

SOFTHARD

Palpography determines radial strain from RF data as a measure for properties of tissue