Artery damage interferes with normal circulation in two ways:
- Wall thickening occurs because arteries respond to high blood pressure by thickening their muscle layers. This muscle thickening does not make arteries stronger. Instead, when arteries become thick, they lose their elasticity, making them more fragile and prone to rupture. Thickening also narrows the passageway, making it harder for blood to flow. Small arteries are especially at risk.
- Atherosclerosis is the buildup of cholesterol (often called "plaque") and scar tissue within the artery walls. This tends to happen in areas with the most turbulent blood flow. Areas where arteries divide or bend can have the most sizable plaque deposits. These deposits narrow the passageway for blood flow. Deposits can also develop cracks that trigger a blood clot to form. A blood clot can create a sudden blockage in the artery, cutting off oxygen. This can result in a heart attack or stroke.
High blood pressure eventually damages the organs that rely most heavily on continuous and efficient blood flow — the heart, brain, kidneys, eyes and blood vessels. These are the "target organs" of high blood pressure.