Heart disease Overview > conditions and diseases >
High Blood Pressure 101
High blood pressure affects millions of Americans, many of whom don’t even know they have it. Here is what you need to know to reduce high blood pressure and lower your risk of heart attack and stroke.
High blood pressure: Also called hypertension, high blood pressure means the pressure of blood being pumped through the arteries is above normal.
Blood pressure is expressed as a fraction in millimeters of mercury (mmHg), such as 110/74 mmHg. The top number (systolic pressure) measures heartbeats; the bottom number (diastolic pressure) measures between beats.
Normal blood pressure: below 120/80 mmHg
Prehypertension: between 120/80 mmHg and 139/89 mmHg
Stage 1: between 140/90 mmHg and 159/99 mmHg
Stage 2: 160/100 mmHg or higher
What Causes High Blood Pressure?
There are two major causes of high blood pressure:
Secondary hypertension: High blood pressure is the result of some underlying, known condition such as a structural blood vessel problem or an existing disease. Secondary hypertension accounts for about 5–10 percent of high blood pressure cases.
Primary hypertension: The cause of high blood pressure is a mystery. This is called essential or primary hypertension and often takes years to develop.
Why It’s Dangerous
High blood pressure overtaxes the heart and cardiovascular system and over time can cause blood vessels to harden, narrow, and even burst.
Hypertension is the most influential risk factor for stroke. It is also a major risk factor for:
Continued on Page 2: Risk Factors