High Blood Pressure Overview
Many people don't know they have high blood pressure (hypertension), because the condition typically has no symptoms. Although people may feel healthy, their uncontrolled high blood pressure is silently damaging their vital organs. If left untreated, the condition can lead to heart attack, stoke, and kidney failure. As a result, high blood pressure is sometimes called the "silent killer."
Each time the heart beats, it sends blood to the arteries (blood vessels that carry blood away from the heart). The arteries then distribute the blood to the rest of the body, providing the body's tissues and organs with needed oxygen and nutrients.
Blood pressure is a measurement of the force exerted on the artery walls. The force is represented as a fraction, such as 120/80 (read as "120 over 80"):
- Systolic blood pressure (the higher number on the top) is the force exerted when the heart contracts (beats).
- Diastolic blood pressure (the lower number on the bottom) is the force exerted when the heart rests between beats.
Blood pressure readings are measured in millimeters of mercury (mm Hg), which is a standard measure of force. The readings are interpreted as follows:
- Normal blood pressure is consistently below 120/80 mm Hg.
- Pre-hypertension is consistently from 120/80 mm Hg to 139/89 mm Hg.
- High blood pressure (hypertension) is consistently 140/90 mm Hg and above.
Blood pressure varies throughout the day and throughout a person's life. Blood pressure is:
- Lowest when people sleep.
- Highest right before people get up in the morning.
- Lower when people relax.
- Higher when people are active, excited, or nervous.
- Affected by a person's diet, health, lifestyle, and medication.
- Typically lowest in children and highest in seniors.
According to the American Heart Association, in 2004 approximately:
- 72 million adult Americans had high blood pressure.
- 30% of people with high blood pressure didn't know they have it.
- Non-Hispanic blacks are more likely to suffer from high blood pressure than non-Hispanic whites.
- 54,000 people died of high blood pressure.
- The death rates from high blood pressure per 100,000 people were:
- 15.6 for white males and 49.9 for black males
- 14.3 for white females and 40.6 for black females