Does calcium deposition play a role in the stability of atheroma? Location may be the key.
BACKGROUND
Rupture of vulnerable atheromatous plaque in the carotid and coronary arteries often leads to stroke and heart attack respectively. The role of calcium deposition and its contribution to plaque stability is controversial. This study uses both an idealized and a patient-specific model to evaluate the effect of a calcium deposit on the stress distribution within an atheromatous plaque.


METHODS
Using a finite-element method, structural analysis was performed on an idealized plaque model and the location of a calcium deposit within it was varied. In addition to the idealized model, in vivo high-resolution MR imaging was performed on 3 patients with carotid atheroma and stress distributions were generated. The individual plaques were chosen as they had calcium at varying locations with respect to the lumen and the fibrous cap.


RESULTS
The predicted maximum stress was increased by 47.5% when the calcium deposit was located in the thin fibrous cap in the model when compared with that in a model without a deposit. The result of adding a calcium deposit either to the lipid core or remote from the lumen resulted in almost no increase in maximal stress.


CONCLUSIONS
Calcification at the thin fibrous cap may result in high stress concentrations, ultimately increasing the risk of plaque rupture. Assessing the location of calcification may, in the future, aid in the risk stratification of patients with carotid stenosis.
Li
Zhi-Yong
ZY
University Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK. ZYL22@cam.ac.uk
Howarth
Simon
S
Tang
Tjun
T
Graves
Martin
M
U-King-Im
Jean
J
Gillard
Jonathan H
JH
D002114:Calcinosis / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D002118:Calcium / Q000032:analysis*; D002318:Cardiovascular Diseases / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D017536:Carotid Artery, Common / Q000737:chemistry* / Q000473:pathology; D016893:Carotid Stenosis / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D003198:Computer Simulation; D020342:Finite Element Analysis; D006801:Humans; D018810:Magnetic Resonance Angiography; D008955:Models, Cardiovascular; D018570:Risk Assessment; D012307:Risk Factors; D012421:Rupture; D013314:Stress, Mechanical
D002118:Calcium