High blood pressure operates with great
stealth. Although it seldom produces symptoms, the intense pounding
of blood gradually damages the organs within the circulation system:
the heart and arteries.
Artery damage interferes with normal
circulation through two changes:
- Wall thickening
occurs because arteries respond to high blood pressure as if they
are part of an athletic weight-training program: They thicken
their muscle layers. Unfortunately, this muscle thickening does
not make arteries stronger. Instead, by thickening, arteries lose
their elasticity, making them more fragile and prone to rupture.
Thickening also narrows the passageway for blood flow. Small
arteries are especially vulnerable.
is a buildup of cholesterol within the artery walls. Just as a
strong ocean tide stirs up sea foam and leaves deposits along the
shore, high blood pressure causes debris from the bloodstream,
including fats and cholesterol, to collect along the artery walls
and to become embedded within the walls. Deposits are thickest in
areas with the most turbulent blood flow — places where important
arteries divide or bend can have the most sizable deposits, or
"plaques." A plaque can 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.