Immunohistochemical staining showed significantly increased amount of macrophage-rich areas in intima, especially near the fibrous caps
, in Operation + HFD + Chronic Stress group [Figure 3]d and [Figure 3]i.
A lipid plaque (figure 4b) is a low-intensity region with poorly delineated borders, a fast IVOCT signal drop off, and little or no OCT signal back scattering, within a lesion that is covered by a fibrous cap
The lesional fibrous cap
is an important factor of stability of atherosclerotic plaques.
Accordingly, G/G genotype could accelerate the degradation of fibrous caps
and unstabilize plaques.
30) Recently, a combination of multi-vessel IVUS and near-infrared spectroscopy techniques has exhibited promising efficacy in the detection of the development of inflamed fibroatheromas with thinner fibrous caps
, greater plaques, and necrotic core areas possessing the characteristics of increased plaque instability.
Cyclic stretching, compression, bending, flexion, shear and pressure fluctuations may fatigue and weaken a fibrous cap
, causing spontaneous rupture.
In addition, it has been suggested that as a metalloproteinase, the PAPP-A produced by activated macrophages may be involved in degradation of the plaque extracellular matrix with consequent weakening of the fibrous cap
A soft core may be more vulnerable to rupture because it may not be able to bear the imposed circumferential stress, which is then redistributed to the fibrous cap
, where it may be critically concentrated.
A fibrous cap
forms over the lesion, enlarging and restructuring it.
The dangerous lesions aren't so much the large, advanced ones," says Rifkind, "but smaller, unstable lesions covered by a small fibrous cap
This unstable plaque, which has a large core of dead cells covered by a thin fibrous cap
, can eventually rupture, forming a big blood clot that can shut down a heart artery.
was displayed as isointensity in T1-weighted image (T1WI) and hyperintensities in proton density weighted image (PDWI) and T2-weighted image (T2WI), lipid core was displayed as isointensity or slight hyperintensities in T1WI, isointensity, hyperintensities or hypointensity in PDWI, and hypointensity in T2WI.
These histologic features include macrophage content, plaque neovascularization, a lipid-rich necrotic core, and a thin fibrous cap
Plaque instability is associated with a high macrophage content and a thin fibrous cap
Inflammation, which is implicated in the formation of early fatty streaks as well as at the onset of adverse cardiovascular events, causes cells within the plaque to secrete enzymes that degrade and weaken the fibrous cap
, leading to rupture of unstable plaques and thrombus (clot) formation.