Ischemic stroke is the most common type of stroke. Usually this type of stroke results from clogged arteries, a condition called atherosclerosis.
The development of arterial atherosclerosis may occur when deposits of cholesterol and plaque accumulate at a tear in the inner lining of an artery. As the deposits harden and occlude the arterial lumen, blood flow to distant tissues decreases and a clot may become lodged, completely blocking the artery.
Fat, cholesterol, and other substances collect on the wall of the arteries, forming a sticky substance called plaque. Over time, the plaque builds up. This often makes it hard for blood to flow properly, which can cause the blood to clot. There are two types of clots:
- A clot that stays in place and interrupts blood flow in the brain is called a cerebral thrombus.
- A clot or plaque fragment forms somewhere in the body(usually the heart or large artery leading to the brain) and then breaks loose and moves through the blood to the brain is called a cerebral embolism.
Atherosclerosis is a disease of the arteries in which fatty material and plaque are deposited in the wall of an artery, resulting in narrowing of the arterial lumen and eventual impairment of blood flow.
Other causes of ischemic stroke include:
- Abnormal heart valve
- Inflammation of the inside lining of the heart chambers and heart
valves ( endocarditis )
- Mechanical heart valve
- Irregular heat rhythm
- A clot can form on a heart valve, break off, and travel to the brain.
For this reason, those with mechanical or abnormal heart valves
often must take blood thinners.
A heart attack or stroke may occur when an area of plaque (atherosclerosis) ruptures and a clot forms over the location, blocking the flow of blood to the organ's tissues.
The build-up of plaque in the internal carotid artery may lead to narrowing and irregularity of the artery's lumen, preventing proper blood flow to the brain. More commonly, as the narrowing worsens, pieces of plaque in the internal carotid artery can break free, travel to the brain and block blood vessels that supply blood to the brain. This leads to stroke, with possible paralysis or other deficits.