What defines unstable plaque in the cardiovascular system?

Unstable plaque in the cardiovascular system is characterized by experiencing small disruptions that can lead to occlusion. This type of plaque is often more prone to rupture, which can cause blood clots and result in significant cardiovascular events such as heart attacks or strokes. The instability of the plaque can be attributed to the composition of the lipid core, inflammation, and the presence of thin fibrous caps that are not firmly anchored to the blood vessel wall. When disruptions occur, fragments of the plaque may be released into the bloodstream, where they can obstruct blood flow.

In contrast, stable plaque tends to be more securely attached to the blood vessel wall and is less likely to rupture. It typically has a thicker fibrous cap and is less prone to cause immediate acute cardiac events. Plaques that are composed entirely of cholesterol deposits or are completely dissolved in the bloodstream do not accurately describe the instability seen in certain plaques. Only those plaques with disrupted structures that lead to potential blockage capture the essence of being unstable in a cardiovascular context.