How critical is fibrous cap thickness to carotid plaque stability? : A flow-plaque interaction model

• Published in: Stroke (1970) Vol. 37; no. 5; pp. 1195 - 1199
• Main Authors: LI, Zhi-Yong, HOWARTH, Simon P. S, TANG, Tjun, GILLARD, Jonathan H
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 01.05.2006
• Subjects: Atherosclerosis (general aspects, experimental research); Atherosclerosis - pathology; Biological and medical sciences; Blood and lymphatic vessels; Cardiology. Vascular system; Carotid Stenosis - complications; Carotid Stenosis - pathology; Fibrosis; Humans; Medical sciences; Models, Theoretical; Neurology; Neurosurgery; Regional Blood Flow; Risk Factors; Rupture, Spontaneous - complications; Skull, brain, vascular surgery; Stress, Mechanical; Stroke - etiology; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Tunica Intima - pathology; Vascular diseases and vascular malformations of the nervous system; Vascular disease; atherosclerosis; stress; Stroke; Nervous system diseases; Carotid; Central nervous system disease; Cardiovascular disease; carotid stenosis; Cerebrovascular disease; Cerebral disorder; rupture
• ISSN: 0039-2499; 1524-4628
• DOI: 10.1161/01.STR.0000217331.61083.3b

Acute cerebral ischemic events are associated with rupture of vulnerable carotid atheroma and subsequent thrombosis. Factors such as luminal stenosis and fibrous cap thickness have been thought to be important risk factors for plaque rupture. We used a flow-structure interaction model to simulate the interaction between blood flow and atheromatous plaque to evaluate the effect of the degree of luminal stenosis and fibrous cap thickness on plaque vulnerability. A coupled nonlinear time-dependent model with a flow-plaque interaction simulation was used to perform flow and stress/strain analysis in a stenotic carotid artery model. The stress distribution within the plaque and the flow conditions within the vessel were calculated for every case when varying the fibrous cap thickness from 0.1 to 2 mm and the degree of luminal stenosis from 10% to 95%. A rupture stress of 300 kPa was chosen to indicate a high risk of plaque rupture. A 1-sample t test was used to compare plaque stresses with the rupture stress. High stress concentrations were found in the plaques in arteries with >70% degree of stenosis. Plaque stresses in arteries with 30% to 70% stenosis increased exponentially as fibrous cap thickness decreased. A decrease of fibrous cap thickness from 0.4 to 0.2 mm resulted in an increase of plaque stress from 141 to 409 kPa in a 40% degree stenotic artery. There is an increase in plaque stress in arteries with a thin fibrous cap. The presence of a moderate carotid stenosis (30% to 70%) with a thin fibrous cap indicates a high risk for plaque rupture. Patients in the future may be risk stratified by measuring both fibrous cap thickness and luminal stenosis.