HIGH BLOOD PRESSURE OVERVIEW
Hypertension is the medical term for high blood pressure. Blood pressure refers to the pressure that blood applies to the inner walls of the arteries. Arteries carry blood from the heart to other organs and parts of the body.
WHAT IS BLOOD PRESSURE?
An individual’s blood pressure is defined by two measurements:
?Systolic pressure is the pressure in the arteries produced when the heart contracts (at the time of a heart beat)
?Diastolic pressure refers the pressure in the arteries during relaxation of the heart between heart beats
Blood pressure is reported as the systolic pressure over diastolic pressure (eg,120/70or 120 over 70).
Untreated high blood pressure increases the strain on the heart and arteries, eventually causing organ damage. High blood pressure increases the risk of heart failure, heart attack (myocardial infarction), stroke, and kidney failure.
HIGH BLOOD PRESSURE DEFINITION
Normal blood pressure — Less than 120 over less than 80
Prehypertension — 121 to 139 over 81 to 89
People with prehypertension are at increased risk of developing hypertension and cardiovascular complications, but drugs used to lower blood pressure are not known to be beneficial in people with prehypertension.
Stage 1: 140 to 159 over 90 to 99
Stage 2: greater than 160 over greater than 100
Most adults with hypertension have primary hypertension (formerly called “essential” hypertension), which means that the cause of the high blood pressure is not known. A small subset of adults has secondary hypertension, which means that there is an underlying and potentially correctable cause, usually a kidney or hormonal disorder.
HIGH BLOOD PRESSURE RISK FACTORS
Hypertension is a common health problem. In the United States, approximately 32 percent of African Americans and 23 percent of white people and Mexican Americans have hypertension.
Hypertension is more common as people grow older. As an example, among people over age 60 years, hypertension occurs in 65 percent of African-American men, 80 percent of African-American women, 55 percent of white men, and 65 percent of white women.
Unfortunately, many people’s blood pressure is not well controlled. According to a national survey, hypertension was in good control in only 25 percent of African Americans and whites and 14 percent of Mexican Americans.
HIGH BLOOD PRESSURE SYMPTOMS
High blood pressure does not usually cause any symptoms.
HIGH BLOOD PRESSURE DIAGNOSIS
Many people are anxious when seeing a doctor or nurse. As a result, you are not diagnosed with hypertension unless your blood pressure is persistently high at two office visits at least one week apart.
The only exceptions to this are if the blood pressure is very high or if you have damage from high blood pressure, such as heart, eye, or kidney injury. Before a decision is made to begin treatment, you may be asked to measure your blood pressure at home or work.
HIGH BLOOD PRESSURE TREATMENT
Untreated hypertension can lead to a variety of complications, including heart disease and stroke. The risk of these complications increases as your blood pressure rises above110/75,which is still in the healthy range. Treating high blood pressure can reduce your risk of heart attack, stroke, and death.
DIETARY CHANGES AND BLOOD PRESSURE
Making changes in what you eat can help to control high blood pressure.
Reduce sodium — The main source of sodium in the diet is the salt contained in packaged and processed foods and in foods from restaurants. Reducing the amount of sodium you consume can lower blood pressure if you have high or borderline high blood pressure.
The body requires a small amount of sodium in the diet. However, most people consume more sodium than they need. A low-sodium diet contains fewer than 2 grams (2,000 milligrams) of sodium each day.
A detailed discussion of low-sodium diets is available separately.
Reduce alcohol — Drinking an excessive amount of alcohol increases your risk of developing high blood pressure. People who have more than two drinks per day have an increased risk of high blood pressure compared to nondrinkers; the risk is greatest when you drink more than five drinks per day.
On the other hand, drinking one (for women) or two (for men) alcoholic beverages per day appears to benefit the heart in people greater than 40 years old. This protective effect applies to people with preexisting high blood pressure.
Eat more fruits and vegetables — Eating a vegetarian diet may reduce high blood pressure and protect against developing high blood pressure. A strict vegetarian diet may not be necessary; eating more fruits and vegetables and low-fat dairy products may also lower blood pressure.
Eat more fiber — Eating an increased amount of fiber may decrease blood pressure. The recommended amount of dietary fiber is 20 to 35 grams of fiber per day. Many breakfast cereals are excellent sources of dietary fiber. More information about increasing fiber is available separately.
Eat more fish — Eating more fish may help to lower blood pressure, especially when combined with weight loss .
Caffeine — Caffeine may cause a small rise in blood pressure, although this effect is usually temporary. Drinking a moderate amount of caffeine (less than 2 cups of coffee per day) does not increase the risk of high blood pressure in most people.
Regular aerobic exercise (walking, running) for 20 to 30 minutes most days of the week can lower your blood pressure, although the effect is not as pronounced among older adults. To maintain this benefit, you must continue to exercise; stopping exercise will allow your blood pressure to become high again.
WEIGHT LOSS AND BLOOD PRESSURE
Being overweight or obese increases your risk of having high blood pressure, diabetes, and cardiovascular disease. The definition of overweight and obese are based upon a calculation called body mass index (BMI) You are said to be overweight if your BMI is greater than 25, while a person with a BMI of 30 or greater is said to be obese. People who are overweight or obese can benefit from losing weight.
To lose weight you must eat less and exercise more.
WHAT IF I STILL HAVE HIGH BLOOD PRESSURE?
If you continue to have high blood pressure despite making changes in your diet, exercising more, and losing weight, you may need a medication to reduce your blood pressure. Medications for high blood pressure are discussed separately.
HIGH BLOOD PRESSURE MEDICATIONS
There are various medications that are commonly used to treat high blood pressure.
Some people will respond well to one drug but not to another. Therefore, it may take time to determine the right drug(s) and proper dose to effectively lower blood pressure with a minimum of side effects.
Although generally well-tolerated, high blood pressure medications can cause side effects; the side effects depend upon the specific drug given, dose, and other factors. Some side effects result from lowering of the blood pressure, usually if the blood pressure lowering is abrupt, and therefore can be caused by any high blood pressure medication. These include dizziness, drowsiness, lightheadedness, or feeling tired. They usually subside after a few weeks when the body has adapted to the lower blood pressure.
Diuretics — Diuretics lower blood pressure mainly by causing the kidneys to excrete more water and sodium, which reduces fluid volume throughout the body and widens (dilates) blood vessels.
The diuretics used to treat high blood pressure are thiazides (chlorthalidone, hydrochlorothiazide, and indapamide). In some cases, a potassium supplement or a potassium-sparing diuretic (amiloride, spironolactone, or triamterene) are given in combination with a thiazide diuretic because the thiazides can cause potassium deficiency since increased amounts of potassium are excreted in the urine.
Side effects — Side effects are uncommon with low doses of thiazide diuretics. Weakness, muscle cramps, and other symptoms can occur as a result of decreased sodium, potassium, and water level. Other symptoms may include reversible impotence and gout attacks.
ACE inhibitors — Angiotensin-converting enzyme (ACE) inhibitors block production of the hormone, angiotensin II, a compound in the blood that causes narrowing of blood vessels and increases blood pressure. By reducing production of angiotensin II, ACE inhibitors allow blood vessels to widen, which lowers blood pressure and improves heart output.
The available ACE inhibitors include benazepril, captopril, enalapril, fosinopril, lisinopril, moexipril, perindopril, quinapril, ramipril, and trandolapril.
Side effects — In some patients, ACE inhibitors cause a persistent dry hacking cough that is reversible when the medication is stopped. Less common side effects include dry mouth, nausea, rash, muscle pain, or occasionally, kidney dysfunction.
A potentially serious complication of ACE inhibitors is angioedema, which occurs in 0.1 to 0.7 percent of people. People with angioedema rapidly (minutes to hours after taking the medication) develop swelling of the lips, tongue, and throat, which can interfere with breathing. These symptoms are a medical emergency, and the ACE inhibitor should be discontinued.
Angiotensin II receptor blockers — The angiotensin II receptor blockers (ARBs) block the effects of angiotensin II on cells in the heart and blood vessels. Similar to ACE inhibitors, ARBs can widen blood vessels and lower blood pressure.
The available ARBs include azilsartan, candesartan, irbesartan, losartan, olmesartan, telmisartan, and valsartan.
Side effects — The main difference between ARBs and ACE inhibitors is that ARBs do not produce cough. Some people who take ARBs experience headache, nausea, dry mouth, abdominal pain, or other side effects. Angioedema is less common with ARBs than with ACE inhibitors.
Calcium channel blockers — Calcium channel blocker drugs reduce the amount of calcium that enters the smooth muscle in blood vessel walls and heart muscle. Muscle cells require calcium to contract. Thus, by inhibiting the flow of calcium across muscle cell membranes, calcium channel blockers cause muscle cells to relax and blood vessels to dilate, reducing blood pressure as well as reducing the force and rate of the heartbeat.
There are two major categories of calcium channel blockers:
?Dihydropyridines, including amlodipine, felodipine, isradipine, nicardipine, nifedipine, and nisoldipine
?Nondihydropyridines, including diltiazem and verapamil
Side effects — The side effects of calcium channel blockers vary with the specific agent used. Patients who take dihydropyridines may develop headache, flushing, nausea, overgrowth of the gum tissue (gingival hyperplasia), or swelling of the extremities (peripheral edema).
Nondihydropyridines can occasionally cause the heart rate to slow too much. Other side effects may include headache and nausea with diltiazem or constipation with verapamil.
Beta blockers — Beta blockers block some of the effects of the sympathetic nervous system, which increases the heart rate and raises blood pressure with stressand/oractivity. Beta blockers lower blood pressure in part by decreasing the rate and force at which the heart pumps blood.
The available beta blockers include acebutolol, atenolol, betaxolol, bisoprolol, metoprolol, nadolol, nebivolol, pindolol, propranolol, and timolol.
Some beta blockers have combined activity, blocking both the beta and alpha receptors (see next section). These include labetalol and carvedilol.
Side effects — Beta blockers may worsen symptoms of asthma, other lung diseases, or blood vessel disease outside the heart (such as peripheral vascular disease). As a result, they normally are not prescribed for patients with such conditions.
In addition, beta blockers may mask symptoms of low blood sugar (hypoglycemia) in people with diabetes who are treated with insulin. Beta blockers can also cause fatigue, insomnia, strange dreams, a decreased ability to exercise, a slow heart rate, rash, and cold hands and feet due to reduced blood flow to the limbs.
Alpha blockers — Alpha blockers relax or reduce the tone of involuntary (ie, smooth) muscle in the walls of blood vessels (vascular smooth muscle), allowing the vessels to widen, thereby lowering blood pressure. An increase in blood vessel diameter is known as “vasodilation.” The available alpha blockers include doxazosin, prazosin, and terazosin.
Side effects — Alpha blockers can cause dizziness, particularly when standing up, and particularly with the first few doses, low blood pressure when standing, or other side effects. They also may increase the risk of developing heart failure. For these reasons, they are not frequently used as a first-line treatment of primary hypertension (formerly called “essential” hypertension). A possible exception is in an older man with symptoms related to enlargement of the prostate; such symptoms may be relieved by alpha blocker therapy.
Direct vasodilators — Direct vasodilators relax or reduce the tone of blood vessels. The two drugs in this class are hydralazine and minoxidil. Minoxidil is typically used in only severe or resistant high blood pressure.
Side effects — Side effects associated with direct vasodilators include headache, constipation, swelling in the lower legs, and rapid heartbeat. These effects are usually minimized by combining the vasodilator with a beta blocker. Minoxidil also may cause excessive hair growth. Rogaine, which is used to treat baldness, is a form of minoxidil that is applied to the skin.
THE PROPER HIGH BLOOD PRESSURE MEDICATION FOR YOU
A healthcare provider will take several factors into account when determining which antihypertensive drug should be tried first. In addition to considering the effectiveness and potential side effects, he or she will consider the person’s general health, sex, age, and race; the severity of the high blood pressure; any additional, underlying medical conditions; and whether particular drugs should not be used.
Certain antihypertensive drugs are specifically recommended for the treatment of particular conditions, even if the person does not have high blood pressure. In many cases, a person with one of these conditions also has high blood pressure. As examples:
?An angiotensin-converting enzyme (ACE) inhibitor is recommended for people with diabetes mellitus who have increased levels of protein in the urine (proteinuria), heart failure, or a prior heart attack.
?Beta blockers are recommended for people with heart failure or a prior heart attack.
?Beta blockers or calcium channel blockers are recommended to control symptoms in people with angina pectoris, which is temporary chest pain caused by an inadequate oxygen supply to heart muscle in patients with coronary artery disease.
There are also certain antihypertensive agents that are not recommended in some people. Some examples include:
?ACE inhibitors and angiotensin II receptor blockers (ARBs) (and many other medications not used to treat high blood pressure) are not recommended during pregnancy.
?Diuretics can worsen gout.
Thus, it is important to mention all current and previous medical problems to the healthcare provider to determine which medication is best.
Combination drug therapy — If a person has very high blood pressure (eg,160/100mmHg or higher), then combination therapy with two drugs at the same time rather than monotherapy with one drug may be theinitial stepin blood pressure treatment. In addition, some people who are first treated with one drug do not have an adequate response with good control of the blood pressure. If this happens, a second medication may be added. Other options include raising the dose of the first drug or substituting a different drug, since some people will respond to a different type of high blood pressure medication.
Adding a second drug, particularly as a single-pill combination, may be:
?More effective than increasing the dose of the first drug.
?Associated with fewer side effects, many of which occur more frequently with higher doses.