Hypocellular and calcified fibrous caps from human atherosclerotic plaques were 1-2 and 4-5 times stiffer than cellular caps (p<0.005), with stiffness increasing at higher stress frequencies.
Observational (n=14)
Does the stiffness of human atherosclerotic plaque fibrous caps depend on their histological composition and the frequency of applied stress?
The stiffness of atherosclerotic fibrous caps depends on their histological composition and increases with the frequency of applied stress, suggesting a biomechanical mechanism for plaque rupture and a potential protective role for heart rate reduction.
p-value: p=<0.005
BACKGROUND: Although thrombosis associated with a fissured atherosclerotic plaque is believed to be the most common cause of acute coronary syndromes, the underlying factors that trigger plaque rupture are currently unknown. However, the mechanical behavior of the plaque is probably of critical importance. METHODS AND RESULTS: To test the hypothesis that the mechanical properties of a plaque are dependent on its composition and, in particular, that the stiffness of fibrous caps changes within the range of frequencies carried by a physiological pressure wave, the stress-strain relation was studied in 27 fibrous caps and related to the underlying histological structure of the fibrous cap. Fibrous caps were obtained during 14 autopsies from the abdominal aorta and were classified by histological examination as cellular (n = 7), hypocellular (n = 9), or calcified (n = 11). Hypocellular fibrous caps were 1-2 times stiffer than cellular caps (p less than 0.005), and calcified caps were 4-5 times stiffer than cellular caps (p less than 0.005). All 27 fibrous caps demonstrated an increase in stiffness with increasing frequencies of stress ranging from 0.05 to 10 Hz; the increase in stiffness was similar in all three histological classes. CONCLUSIONS: We conclude that the stiffness of fibrous caps from human atherosclerotic plaques is related to the underlying histological structure and that the stiffness increases with frequency in the range of physiological heart rates. The protective benefit of beta-adrenergic receptor blocking agents in coronary artery disease may, in part, be related to the frequency dependence of atherosclerotic plaque stiffness.
Lee et al. (Wed,) conducted a observational in Atherosclerotic plaques (n=14). Histological classification (hypocellular or calcified) vs. Cellular fibrous caps was evaluated on Stiffness (stress-strain relation) (p=<0.005). Hypocellular and calcified fibrous caps from human atherosclerotic plaques were 1-2 and 4-5 times stiffer than cellular caps (p<0.005), with stiffness increasing at higher stress frequencies.