High Blood Pressure – Pathophysiology
High blood pressure is a common condition in which the force of the blood against your artery walls is high enough that it may eventually cause health problems, such as heart disease.
Blood pressure is determined by the amount of blood your heart pumps and the amount of resistance to blood flow in your arteries. The more blood your heart pumps and the narrower your arteries, the higher your blood pressure.
You can have high blood pressure (hypertension) for years without any symptoms. Even without symptoms, damage to blood vessels and your heart continues and can be detected. Uncontrolled high blood pressure increases your risk of serious health problems, including heart attack and stroke.
High blood pressure generally develops over many years, and it affects nearly everyone eventually. Fortunately, high blood pressure can be easily detected. And once you know you have high blood pressure, you can work with your doctor to control it.
Most people with high blood pressure have no signs or symptoms, even if blood pressure readings reach dangerously high levels.
Although a few people with early-stage high blood pressure may have dull headaches, dizzy spells or a few more nosebleeds than normal, these signs and symptoms usually don’t occur until high blood pressure has reached a severe or life-threatening stage.
When to see a doctor
You’ll likely have your blood pressure taken as part of a routine doctor’s appointment.
Ask your doctor for a blood pressure reading at least every two years starting at age 18. Blood pressure should be checked in both arms to determine if there is a difference. Your doctor will likely recommend more frequent readings if you’ve already been diagnosed with high blood pressure or other risk factors for cardiovascular disease. Children age 3 and older will usually have their blood pressure measured as a part of their yearly checkups.
If you don’t regularly see your doctor, you may be able to get a free blood pressure screening at a health resource fair or other locations in your community. You can also find machines in some stores that will measure your blood pressure for free, but these machines can give you inaccurate results.
here are two types of high blood pressure.
Primary (essential) hypertension
For most adults, there’s no identifiable cause of high blood pressure. This type of high blood pressure, called essential hypertension or primary hypertension, tends to develop gradually over many years.
Some people have high blood pressure caused by an underlying condition. This type of high blood pressure, called secondary hypertension, tends to appear suddenly and cause higher blood pressure than does primary hypertension. Various conditions and medications can lead to secondary hypertension, including:
- Kidney problems
- Adrenal gland tumors
- Thyroid problems
- Certain defects in blood vessels you’re born with (congenital)
- Certain medications, such as birth control pills, cold remedies, decongestants, over-the-counter pain relievers and some prescription drugs
- Illegal drugs, such as cocaine and amphetamines
- Alcohol abuse or chronic alcohol use
- Obstructive sleep apnea
High blood pressure has many risk factors, including:
- Age. The risk of high blood pressure increases as you age. Through early middle age, or about age 45, high blood pressure is more common in men. Women are more likely to develop high blood pressure after age 65.
- Race. High blood pressure is particularly common among blacks, often developing at an earlier age than it does in whites. Serious complications, such as stroke, heart attack, and kidney failure, also are more common in blacks.
- Family history. High blood pressure tends to run in families.
- Being overweight or obese. The more you weigh the more blood you need to supply oxygen and nutrients to your tissues. As the volume of blood circulated through your blood vessels increases, so does the pressure on your artery walls.
- Not being physically active. People who are inactive tend to have higher heart rates. The higher your heart rate, the harder your heart must work with each contraction and the stronger the force on your arteries. Lack of physical activity also increases the risk of being overweight.
- Using tobacco. Not only does smoking or chewing tobacco immediately raise your blood pressure temporarily, but the chemicals in tobacco can damage the lining of your artery walls. This can cause your arteries to narrow, increasing your blood pressure. Secondhand smoke also can increase your blood pressure.
- Too much salt (sodium) in your diet. Too much sodium in your diet can cause your body to retain fluid, which increases blood pressure.
- Too little potassium in your diet. Potassium helps balance the amount of sodium in your cells. If you don’t get enough potassium in your diet or retain enough potassium, you may accumulate too much sodium in your blood.
- Too little vitamin D in your diet. It’s uncertain if having too little vitamin D in your diet can lead to high blood pressure. Vitamin D may affect an enzyme produced by your kidneys that affects your blood pressure.
- Drinking too much alcohol. Over time, heavy drinking can damage your heart. Having more than two drinks a day for men and more than one drink a day for women may affect your blood pressure.If you drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women of all ages and men older than age 65, and up to two drinks a day for men age 65 and younger.
- Stress. High levels of stress can lead to a temporary increase in blood pressure. If you try to relax by eating more, using tobacco or drinking alcohol, you may only increase problems with high blood pressure.
- Certain chronic conditions. Certain chronic conditions also may increase your risk of high blood pressure, such as kidney disease and sleep apnea.
Sometimes pregnancy contributes to high blood pressure, as well.
Although high blood pressure is most common in adults, children may be at risk, too. For some children, high blood pressure is caused by problems with the kidneys or heart. But for a growing number of kids, poor lifestyle habits, such as an unhealthy diet, obesity and lack of exercise, contribute to high blood pressure.
The excessive pressure on your artery walls caused by high blood pressure can damage your blood vessels, as well as organs in your body. The higher your blood pressure and the longer it goes uncontrolled, the greater the damage.
Uncontrolled high blood pressure can lead to:
- Heart attack or stroke. High blood pressure can cause hardening and thickening of the arteries (atherosclerosis), which can lead to a heart attack, stroke or other complications.
- Aneurysm. Increased blood pressure can cause your blood vessels to weaken and bulge, forming an aneurysm. If an aneurysm ruptures, it can be life-threatening.
- Heart failure. To pump blood against the higher pressure in your vessels, your heart muscle thickens. Eventually, the thickened muscle may have a hard time pumping enough blood to meet your body’s needs, which can lead to heart failure.
- Weakened and narrowed blood vessels in your kidneys.This can prevent these organs from functioning normally.
- Thickened, narrowed or torn blood vessels in the eyes.This can result in vision loss.
- Metabolic syndrome. This syndrome is a cluster of disorders of your body’s metabolism, including increased waist circumference; high triglycerides; low high-density lipoprotein (HDL); or “good,” cholesterol; high blood pressure; and high insulin levels.If you have high blood pressure, you’re more likely to have other components of metabolic syndrome. The more components you have, the greater your risk of developing diabetes, heart disease or stroke.
- Trouble with memory or understanding. Uncontrolled high blood pressure may also affect your ability to think, remember and learn. Trouble with memory or understanding concepts is more common in people with high blood pressure.
Tests and diagnosis
To measure your blood pressure, your doctor or a specialist will usually place an inflatable arm cuff around your arm and measure your blood pressure using a pressure-measuring gauge.
A blood pressure reading, given in millimeters of mercury (mm Hg), has two numbers. The first, or upper, number measures the pressure in your arteries when your heart beats (systolic pressure). The second, or lower, number measures the pressure in your arteries between beats (diastolic pressure).
Blood pressure measurements fall into four general categories:
- Normal blood pressure. Your blood pressure is normal if it’s below 120/80 mm Hg. However, some doctors recommend 115/75 mm Hg as a better goal. Once blood pressure rises above 115/75 mm Hg, the risk of cardiovascular disease begins to increase.
- Prehypertension. Prehypertension is a systolic pressure ranging from 120 to 139 mm Hg or a diastolic pressure ranging from 80 to 89 mm Hg. Prehypertension tends to get worse over time.
- Stage 1 hypertension. Stage 1 hypertension is a systolic pressure ranging from 140 to 159 mm Hg or a diastolic pressure ranging from 90 to 99 mm Hg.
- Stage 2 hypertension. More severe hypertension, stage 2 hypertension is a systolic pressure of 160 mm Hg or higher or a diastolic pressure of 100 mm Hg or higher.
Both numbers in a blood pressure reading are important. But after age 60, the systolic reading is even more significant. Isolated systolic hypertension — when diastolic pressure is normal but systolic pressure is high — is a common type of high blood pressure among people older than 60.
Your doctor will likely take two to three blood pressure readings each at three or more separate appointments before diagnosing you with high blood pressure. This is because blood pressure normally varies throughout the day, and sometimes specifically during visits to the doctor, a condition called white-coat hypertension. Your blood pressure should be measured in both arms to determine if there is a difference. Your doctor may ask you to record your blood pressure at home and at work to provide additional information.
If you have any type of high blood pressure, your doctor will review your medical history and conduct a physical examination.
Your doctor may also recommend routine tests, such as a urine test (urinalysis), blood tests and an electrocardiogram — a test that measures your heart’s electrical activity. Your doctor may also recommend additional tests, such as a cholesterol test, to check for more signs of heart disease.
Taking your blood pressure at home
An important way to check if your blood pressure treatment is working, or to diagnose worsening high blood pressure, is to monitor your blood pressure at home. Home blood pressure monitors are widely available, and you don’t need a prescription to buy one. Talk to your doctor about how to get started.
Treatments and drugs
Changing your lifestyle can go a long way toward controlling high blood pressure. Your doctor may recommend you eat a healthy diet with less salt, exercise regularly, quit smoking and maintain a healthy weight. But sometimes lifestyle changes aren’t enough.
In addition to lifestyle changes, your doctor may recommend medication to lower your blood pressure.
Your blood pressure treatment goal depends on how healthy you are.
|*Although 120/80 mm Hg or lower is the ideal blood pressure goal, doctors are unsure if you need treatment (medications) to reach that level.|
|Less than150/90 mm Hg||If you’re a healthy adult age 60 or older|
|Less than140/90 mm Hg||If you’re a healthy adult younger than age 60|
|Less than140/90 mm Hg||If you have chronic kidney disease, diabetes or coronary artery disease or are at high risk of coronary artery disease|
If you’re age 60 or older, and use of medications results in lower systolic blood pressure (such as less than 140 mm Hg), your medications won’t need to be changed unless they cause negative effects to your health or quality of life.
Also, people older than 60 commonly have isolated systolic hypertension — when diastolic pressure is normal but systolic pressure is high.
The category of medication your doctor prescribes depends on your blood pressure measurements and whether you also have other medical problems.
Medications to treat high blood pressure
- Thiazide diuretics. Diuretics, sometimes called water pills, are medications that act on your kidneys to help your body eliminate sodium and water, reducing blood volume.Thiazide diuretics are often the first, but not the only, choice in high blood pressure medications. If you’re not taking a diuretic and your blood pressure remains high, talk to your doctor about adding one or replacing a drug you currently take with a diuretic. Diuretics or calcium channel blockers may work better for blacks than do angiotensin-converting enzyme (ACE) inhibitors alone.
- Beta blockers. These medications reduce the workload on your heart and open your blood vessels, causing your heart to beat slower and with less force.When prescribed alone, beta blockers don’t work as well, especially in older adults, but may be effective when combined with other blood pressure medications.
- Angiotensin-converting enzyme (ACE) inhibitors. These medications help relax blood vessels by blocking the formation of a natural chemical that narrows blood vessels. People with chronic kidney disease may benefit from ACE inhibitors as one of their medications.
- Angiotensin II receptor blockers (ARBs). These medications help relax blood vessels by blocking the action, not the formation, of a natural chemical that narrows blood vessels. People with chronic kidney disease may benefit from ARBs as one of their medications.
- Calcium channel blockers. These medications help relax the muscles of your blood vessels. Some slow your heart rate. Calcium channel blockers may work better for older people and blacks than do ACE inhibitors alone.Grapefruit juice interacts with some calcium channel blockers, increasing blood levels of the medication and putting you at higher risk of side effects. Talk to your doctor or pharmacist if you’re concerned about interactions.
- Renin inhibitors. Aliskiren (Tekturna) slows down the production of renin, an enzyme produced by your kidneys that starts a chain of chemical steps that increases blood pressure.Tekturna works by reducing the ability of renin to begin this process. Due to a risk of serious complications, including stroke, you shouldn’t take aliskiren with ACE inhibitors or ARBs.
Additional medications to treat high blood pressure
If you’re having trouble reaching your blood pressure goal with combinations of the above medications, your doctor may prescribe:
- Alpha blockers. These medications reduce nerve impulses to blood vessels, reducing the effects of natural chemicals that narrow blood vessels.
- Alpha-beta blockers. In addition to reducing nerve impulses to blood vessels, alpha-beta blockers slow the heartbeat to reduce the amount of blood that must be pumped through the vessels.
- Central-acting agents. These medications prevent your brain from signaling your nervous system to increase your heart rate and narrow your blood vessels.
- Vasodilators. These medications work directly on the muscles in the walls of your arteries, preventing the muscles from tightening and your arteries from narrowing.
- Aldosterone antagonists. Examples are spironolactone (Aldactone) and eplerenone (Inspra). These drugs block the effect of a natural chemical that can lead to salt and fluid retention, which can contribute to high blood pressure.
Once your blood pressure is under control, your doctor may have you take a daily aspirin to reduce your risk of cardiovascular disorders.
To reduce the number of daily medication doses you need, your doctor may prescribe a combination of low-dose medications rather than larger doses of one single drug. In fact, two or more blood pressure drugs may be more effective than one. Sometimes finding the most effective medication or combination of drugs is a matter of trial and error.
Lifestyle changes to treat high blood pressure
No matter what medications your doctor prescribes to treat your high blood pressure, you’ll need to make lifestyle changes to lower your blood pressure.
Your doctor may recommend several lifestyle changes, including:
- Eating a healthier diet with less salt (the Dietary Approaches to Stop Hypertension, or DASH, diet)
- Exercising regularly
- Quitting smoking
- Losing weight
Resistant hypertension: When your blood pressure is difficult to control
If your blood pressure remains stubbornly high despite taking at least three different types of high blood pressure drugs, one of which should be a diuretic, you may have resistant hypertension.
Resistant hypertension is blood pressure that’s resistant to treatment. People who have controlled high blood pressure but are taking four different types of medications at the same time to achieve that control also are considered to have resistant hypertension.
Having resistant hypertension doesn’t mean your blood pressure will never get lower. In fact, if you and your doctor can identify what’s behind your persistently high blood pressure, there’s a good chance you can meet your goal with the help of treatment that’s more effective.
Your doctor or hypertension specialist can evaluate whether the medications and doses you’re taking for your high blood pressure are appropriate. You may have to fine-tune your medications to come up with the most effective combination and doses.
In addition, you and your doctor can review medications you’re taking for other conditions. Some medications, foods or supplements can worsen high blood pressure or prevent your high blood pressure medications from working effectively. Be open and honest with your doctor about all the medications or supplements you take.
If you don’t take your high blood pressure medications exactly as directed, your blood pressure can pay the price. If you skip doses because you can’t afford the medication, because you have side effects or because you simply forget to take your medications, talk to your doctor about solutions. Don’t change your treatment without your doctor’s guidance.