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In this article:
Key Points
- Blood pressure is created both by blood pumping into the body from the heart, and by the resistance of the body’s arteries to the flow of blood.
- High blood pressure, or hypertension, often causes no noticeable symptoms and is called "the silent killer."
- Atherosclerosis and coronary artery disease can cause hypertension.
- New guidelines set a target "normal" blood pressure at less than 120 (systolic)/less than 80 (diastolic) mm Hg.
- A normal resting adult heart rate is approximately 60 to 75 beats per minute.
Both you and your doctor can learn a great deal about your health from blood pressure and pulse measurements during your checkups. Understanding what these numbers mean can also help you monitor your health.
What blood pressure measures
Blood pressure is the pressure of the blood against the walls of the arteries as blood flows through the body. This pressure is created by both the blood pumping into the body from the heart, and by the resistance of your arteries to the flow of blood. When blood pressure increases, the heart must work harder to send blood throughout the body. Your doctor will take several blood pressure readings over the course of a few office checkups. If your blood pressure is higher than the accepted range at each of these visits, then your doctor may diagnose high blood pressure (also called hypertension).
Often, high blood pressure causes no noticeable symptoms and is frequently called "the silent killer." Pressure in the arteries can increase because of various reasons such as atherosclerosis and coronary artery disease. Arteries must be flexible to be able to adjust to changes in pressure. If your arteries are narrow and stiff because of atherosclerosis, your blood pressure can increase, forcing the heart to work harder while it pumps blood throughout the body. Over time and without treatment, high blood pressure may put you at risk for developing heart disease or other illnesses such as stroke or kidney disease. Learn more in Coronary Artery Disease.
Blood pressure is measured in millimeters of mercury, or mm Hg, in reference to the mercury that was used in older blood pressure measuring devices. Most blood pressure devices today measure changes in blood pressure digitally. The systolic blood pressure (the top, or bigger number) is the pressure when the heart squeezes, or contracts. The diastolic blood pressure (the bottom, or smaller number) is the pressure between beats, when the heart relaxes. For example, your doctor may tell you that your blood pressure is 120/80 ("120 over 80"). This means that your systolic pressure (when your heart contracts) is 120 mm Hg and your diastolic pressure (when your heart relaxes) is 80 mm Hg.
What is target blood pressure?
You may want to work even harder to keep your blood pressure in check, in light of new guidelines that the National Heart, Lung, and Blood Institute (NHLBI) released in early 2003. Here are the new definitions:
- Normal: less than 120/less than 80 mm Hg
- Prehypertension: 120 to 139/80 to 89 mm Hg
- Stage 1 Hypertension: 140 to 159/90 to 99 mm Hg
- Stage 2 Hypertension: 160 or greater/100 or greater mm Hg1
High blood pressure has become an increasingly important public health concern. A study published in the Journal of the American Medical Association estimates that middle-aged and senior Americans have a 90% risk of developing high blood pressure during their lifetime.2
But doctors say high blood pressure isn't inevitable. Strategies such as keeping your weight down, exercising regularly, and eating low-fat, low-cholesterol, and/or low-salt meals go a long way toward preventing this problem. In fact, you may want to talk to your doctor about which type of food plan may be best for you. See Nutrition Matters for more information.
According to the new guidelines, people with prehypertension should make healthy lifestyle changes, but in general do not need blood pressure medication unless they have a condition such as diabetes or chronic kidney disease.
However, people with Stage 1 or 2 hypertension should make healthy lifestyle changes and talk to their doctors about blood pressure medication. People with high blood pressure should aim to keep their reading at less than 140/90 mm Hg, while people who have high blood pressure along with diabetes or chronic kidney disease should strive for a goal of less than 130/80 mm Hg. Ask your doctor about which strategies might be best for you. See Nutrition Matters and Exercise for Heart Health for more information.
Your pulse
Your pulse (also called your heart rate) tells you how fast your heart is beating. Your body's conduction system—the electrical system of the heart—sends out electrical signals to stimulate the heart to beat (contract), pumping blood throughout the body.
The speed and strength of the contraction are affected by signals from the central nervous system that help the body respond to its surroundings. The heart usually beats faster in times of stress, for example, or when you're running up a flight of stairs or trying to catch a bus. During relaxation, and for people who exercise regularly, the heart rate is usually lower. A normal resting heart rate averages about 60 to 75 beats per minute.
Your resting heart rate changes considerably over your lifetime. At birth, your heart rate is around 130 beats per minute. By age 12 it has dropped to around 80 beats per minute, and it continues to fall as you reach adulthood, when it averages about 60 to 75 beats per minute.3 When you exercise or experience stress or a fever, your heart rate temporarily increases.4 For people who exercise regularly, the resting heart rate is usually lower.
Sources
1. National Heart, Lung, and Blood Institute, National Institutes of Health, The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Express version: NIH Publication No. 13-5233. May 2003. http://www.nhlbi.nih.gov/guidelines/hypertension/express.pdf
2. Vasan, R.S., Beiser, A., et al. "Residual Lifetime Risk for Developing Hypertension in Middle-aged Women and Men: The Framingham Heart Study." Journal of the American Medical Association, 2002, Vol. 287, No. 8. 1003-1010. PubMed
3. Heart rate and heart rate monitors. The British Heart Foundation. http://www.bhf.org.uk/questions/index.asp?secondlevel=370&third
level=707, Accessed June 2, 2004.
4. The New Encyclopedia Britannica, Volume 5 Micropedia Ready Reference, 2003, 782-783.
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