High blood pressure: Common, commonly uncontrolled, and dangerous

Content provided by the Faculty of the Harvard Medical School

High blood pressure: Common, commonly uncontrolled, and dangerous

10 steps for fighting the good fight against high blood pressure

It’s been more than a century since a Russian surgeon first described the simple and precise way to measure blood pressure that is still in use. We’ve learned a lot since then about what influences blood pressure and about how high blood pressure can wreak havoc throughout the body. What we haven’t managed to do is get the public, and a fair number of doctors, to take high blood pressure seriously. Nearly two-thirds of the 65 million American adults with high blood pressure don’t have it under control. That’s a big problem, because it’s a major cause of stroke, heart attack, heart and kidney failure, and early death.

In this special feature, we take a look at the latest thinking on this topic and offer 10 steps for getting your blood pressure under control and keeping it there.

Blood pressure basics

Some pressure is absolutely essential for circulation. Without it, blood couldn’t move from the heart to the brain and toes and back again. The heart provides the driving force — each contraction of the left ventricle, the heart’s main pumping chamber, creates a wave of pressure that passes through the aorta and all the arteries in the body.

Relaxed and flexible arteries offer a healthy amount of resistance to each pulse of blood. Arteries that are tensed, constricted, or rigid offer more resistance, which shows up as higher blood pressure. It also makes the heart work harder.

High blood pressure is not a disease. Instead, it is a sign that something isn’t right in the heart, blood vessels, kidneys, or elsewhere. Sometimes it stems from the overproduction of hormones by the thyroid or adrenal glands. It can also be caused by the use of prescription or over-the-counter medications such as aspirin, ibuprofen, pseudoephedrine, some antidepressants, steroids, and others. Most of the time, though, high blood pressure can’t be traced to a specific source.

Doctors use the term hypertension. We’ll stick with the more descriptive high blood pressure. Both mean the same thing.

Measuring change

Blood pressure changes constantly. It responds instantly to what you are doing, thinking, and feeling. It also follows a daily cycle, hitting a low point just before waking and peaking during midday. The reading taken in your doctor’s office is merely a snapshot. All too often it’s a shadowy, out-of-focus snapshot. Many doctors, nurses, and medical assistants get incorrect readings because they don’t follow the proper procedures for measuring blood pressure. What’s more, some people have higher blood pressure in the doctor’s office than at home, a discrepancy known as white-coat hypertension. Checking your blood pressure at home gives you and your doctor a much more accurate idea of your real blood pressure.

No matter where your blood pressure is measured, these steps should be followed each time:

• Avoid tobacco and caffeine for at least 30 minutes before the test.

• Sit quietly for five minutes before the test.

• During the measurement, sit in a chair with your feet on the floor; your arm should be supported so your elbow is at about heart level.

• The inflatable part of the cuff should be placed on bare skin, not over a shirt, and should encircle at least 80% of your arm.

• Measure blood pressure twice, with a brief break in between.

A standard blood pressure reading generates two numbers, as in 128/78. Each number represents millimeters of mercury (mm Hg), because the traditional measuring device used a glass column filled with mercury. The top number is the systolic pressure; the bottom number, the diastolic pressure.

Systolic pressure reflects the amount of pressure generated during systole (SIS-tuh-lee), the heart’s pumping phase. It shows how hard the heart is working to push blood through the arteries. Diastolic pressure is the pressure during diastole (die-AS-tuh-lee), when the heart refills with blood between beats. It reflects how forcefully the arteries are being stretched most of the time.

Alternative ways to gauge the state of the heart and blood vessels are gaining ground. One is pulse pressure, which is calculated by subtracting diastolic pressure from systolic pressure. The bigger the difference, the stiffer the arteries. Devices that measure the time it takes for a pulse wave to travel through the arterial system or that analyze the shape and frequency of blood pressure waves are also being used to judge the stiffness of arteries. Another approach, called impedance cardiography, tracks what happens to small electrical signals sent through the chest and blood vessels. This can assess the heart’s ability to deliver blood to the body, the force the heart must pump against, and the amount of fluid in the chest.

Feeling the pressure The constant stress of high blood pressure causes physical and functional deterioration wherever blood vessels reach — every nook and cranny of the body. We’ll work our way from the blood vessels and heart toward the other so-called target organs. Blood vessels. There’s a sort of chicken-and-egg connection between high blood pressure and blood vessels. High blood pressure engineers changes in artery walls, while changes in artery walls contribute to high blood pressure. The three main effects are: Stiffening. “Hardening of the arteries” is a perfectly descriptive term for one consequence of high blood pressure. Over time, the artery remodels itself, fortifying the muscular middle wall (media). The thicker the media, the less flexible the artery and the less space available for blood flow. Plaque. Subtle damage caused by high blood pressure can ignite hot spots of inflammation along artery walls. These tend to evolve into areas of cholesterol-laden plaque, which can restrict blood flow, burst to cause a heart attack or stroke, or otherwise compromise the integrity or function of the artery. Weak spots. High blood pressure sometimes weakens the artery wall instead of strengthening it. When such a weak spot balloons out, like an inner tube bulging through a weak tire, it is called an aneurysm. Aneurysms often form in the aorta (the largest blood vessel in the body) and in the brain. If an aortic aneurysm pops, the resulting sudden, massive internal bleeding is almost always fatal. A ruptured aneurysm in the brain causes the type of stroke known as a hemorrhagic stroke. Heart. Arterial resistance to blood flow forces the heart to work harder. Overworked heart muscle can respond by bulking up, like a weightlifter. While this may help for a while, it can lead in two separate but equally damaging directions. The extra muscle can become flabby, causing the heart to enlarge and contractions to weaken. Or the extra muscle can reduce the open space inside the ventricles and make the heart muscle stiffer, so it has trouble filling with blood between beats. Each of these can lead to heart failure. Brain. One of the most feared consequences of high blood pressure is a stroke, the third leading cause of death in America and the leading cause of serious long-term disability. Pressure-related damage to small blood vessels in the brain can lead to more subtle but no less disabling consequences — memory loss or dementia. Kidneys. Sustained high blood pressure damages glomeruli, the tiny tangles of blood vessels that filter sodium, waste products, and water from the bloodstream. Kidney failure is a common consequence of high blood pressure. The opposite is also true — kidney disease contributes to high blood pressure. Eyes. High blood pressure can narrow blood vessels in the eye, create aneurysms along blood vessel walls, block retinal veins, create areas of dead or dying tissue caused by lack of blood flow, or swell the base of the optic nerve. These changes can impair vision and lead to blindness. Sex life. Damage to arteries supplying the penis and vagina can interfere with a satisfying sex life, as can some drugs used to treat high blood pressure. Problems include impotence and ejaculation problems in men, painful or uncomfortable intercourse and difficulty having orgasms in women, and lack of desire in both.

What’s normal?

The definitions of normal and high blood pressure have been evolving over the years. Well into the 1970s, doctors didn’t worry until systolic blood pressure topped 160 or diastolic jutted above 95. Since then, the cutoff between normal — meaning healthy — and high has been steadily falling.

The latest national guidelines (JNC-7) that doctors use to diagnose and treat high blood pressure set out four categories: normal (under 120/80), prehypertension (systolic 120–139 or diastolic 80–89), stage 1 hypertension (systolic 140–159 or diastolic 90–99), and stage 2 hypertension (systolic 160 or higher or diastolic 100 or higher). Each comes with recommendations on what should be done to decrease or control blood pressure, starting with lifestyle changes in prehypertension and moving on to medications and other therapies.

The American Society of Hypertension (ASH) believes that there’s more to the diagnosis than the numerical reading. A panel of ASH experts has proposed that early warnings of trouble in the heart, blood vessels, kidneys, or other target organs, or signs of damage in them, should be given as much emphasis as the blood pressure level itself. The group’s approach makes sense — it’s a bit misleading to say that someone with a blood pressure of 119/79 is okay while someone whose blood pressure is 121/81 has prehypertension.

Looking at an individual’s overall risk, instead of relying on a single number like blood pressure, means more work for doctors. But it would also lead to more aggressive efforts to identify and treat the people who need the most attention — those with diabetes, kidney disease, or other signs of damage connected with high blood pressure.

10 steps to better pressure

High blood pressure isn’t usually something that can be cured. Like an in-law who comes to stay for good, it’s something most people need to learn to live with. Drugs offer an easy fix, but most also cause unwanted side effects. Making healthful lifestyle changes is harder, but it yields benefits far beyond better blood pressure. That’s why it makes sense to start with these, and add medications only if needed. Here are 10 steps that can help you lower your blood pressure and keep it under control.

1. Check it. You can’t do much about your blood pressure unless you know what it is. Your doctor should check it at every visit. Measuring it at home is even better. Relatively inexpensive home monitors are available in most pharmacies.

2. Get moving. Regular exercise, even something as simple as brisk walking, improves blood vessel flexibility and heart function. It can lower blood pressure by 10 points, prevent the onset of high blood pressure, or let you reduce your dosage of blood pressure medications.

3. Eat right. A landmark study called Dietary Approaches to Stop Hypertension (DASH) showed that you can eat your way to better blood pressure. The DASH diet emphasizes fruits, vegetables, low-fat dairy products, whole grains, poultry, fish, and nuts, and downplays red meat, sweets, sugar-containing beverages, and saturated fat and cholesterol.

4. Control your weight. If you are carrying too many pounds for your frame, losing weight can lower your blood pressure. You don’t need to become rail-thin — losing 10% of your current weight, or even 10 pounds, can make a big difference.

5. Don’t smoke. Nicotine constricts small blood vessels. Smoking a cigarette can cause a 20-point spike in systolic blood pressure. Quitting is tough, but there are now more aids to help.

6. Drink alcohol in moderation. A drink a day for women and one or two a day for men is good for the heart and blood vessels. Going beyond that can contribute to higher blood pressure.

7. Shake up your salts. Too much sodium and too little potassium boost blood pressure in people who are sensitive to salt. The imbalance is so great that the American Medical Association is calling for food makers and restaurants to cut the sodium content of food by 50% by 2016. Aim for less than 1.5 grams of sodium a day, and at least 4.7 grams of potassium.

8. Sleep is good. Burning the candle at both ends night after night can contribute to high blood pressure, not to mention increase the chances of developing heart disease or a sudden cardiac arrest. How much sleep is enough? At least six hours a night, though eight hours is probably more like it for most people.

9. Reduce stress. As surely as mental and emotional stress can raise blood pressure, meditation, deep breathing, and other stress-busting activities can lower it.

10. Stick with your medications. Taking pills to keep your blood pressure in check won’t make you feel any different. But it can keep you from having a stroke, heart attack, or other problem.

Dozens of drugs are available for lowering blood pressure. They come in a range of regimens (once a day to several times a day) and costs, and have a range of effects on other conditions, interactions with other drugs, and potential side effects.

One of the big controversies in medicine today is which drug is best for treating high blood pressure. Current guidelines as of 2006 say that the first choice should be an inexpensive diuretic (water pill). Some experts argue that an ACE inhibitor or a calcium-channel blocker is a better place to start. In reality, what’s best for you isn’t necessarily right for someone else. Most people need more than one medication to get their blood pressure under control, and one of these should probably be a diuretic.

High blood pressure, like almost everything else in medicine, is a highly personal condition. Preventing it, and keeping it from doing you harm, requires careful, individualized evaluation from your doctor and focused commitment on your part.

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Last updated:	August 22, 2006