What is high blood pressure? - causes high blood pressure

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Created on Thursday, 05 July 2012 00:00

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How is high blood pressure treated?

Goals of treatment

High blood pressure is usually present for years before its complications develop. Ideally, hypertension is treated early, before it damages critical organs in the body. Increased public awareness and screening programs to detect early, uncomplicated hypertension are keys to successful treatment. Successful early treatment of high blood pressure can significantly decrease the risk of stroke, heart attack, and kidney failure.

The goal for patients with combined systolic and diastolic hypertension is to attain a blood pressure of 140/85 mm Hg. Bringing the blood pressure down even lower may be desirable in African American patients, and patients with diabetes or chronic kidney disease. Although life style changes in pre-hypertensive patients are appropriate, it is not well established that treatment with medication of patients with pre-hypertension is beneficial.

Treatment with combinations of drugs for high blood pressure

The use of combination drug therapy for hypertension is common. At times, using smaller amounts of one or more drugs in combination can minimize side effects while maximizing the anti-hypertensive effect. For example, diuretics, which also can be used alone, are more often used in a low dose in combination with another class of anti-hypertensive medications. This way, the diuretic has fewer side effects while improving the blood pressure - lowering effect of the other drug. Diuretics also are added to other anti-hypertensive medications when a patient with hypertension also has fluid retention and swelling (edema).

ACE inhibitors or angiotensin receptor blockers may be useful in combination with most other anti-hypertensive medications. These kinds of drugs have additive effects in treating patients with cardiomyopathies and proteinuria. Another useful combination is that of a beta-blocker with an alpha-blocker in patients with high blood pressure and enlargement of the prostate gland in order to treat both conditions simultaneously. Caution is necessary when combining two drugs that both lower the heart rate. For example, patients receiving a combination of a beta-blocker to a non-dihydropyridine calcium channel blocker [for example, diltiazem (Cardizem, Dilacor, Tiazac) or verapamil (Calan, Verelan, Isoptin, Covera-HS)] need to be monitored carefully to avoid an excessively slow heart rate (bradycardia). Combining alpha and beta-blockers such as carvedilol (Coreg) and labetalol (Normodyne, Trandate) is useful for cardiomyopathies and for hypertension patients.

Starting treatment for high blood pressure

Blood pressure persistently higher than 140/ 90 mm Hg usually is treated with lifestyle modifications and medication. More aggressive treatment may be recommended in certain circumstances if the diastolic pressure remains at a borderline level (usually less than 90 mm Hg, yet persistently above 85). These circumstances include borderline diastolic pressures in association with end-organ damage, systolic hypertension, or factors that increase the risk of cardiovascular disease, such as age over 65 years, African American descent, smoking, hyperlipemia (elevated blood fats), or diabetes.

Any one of several classes of medications may be started, except the alpha-blocker medications, which are used only in combination with another anti-hypertensive medication in specific medical situations. (See the next section for a more detailed discussion of each of the several classes of anti-hypertensive medications.)

In some situations, certain classes of anti-hypertensive drugs are preferable to others as the first line (preferred first choice) drugs. Angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor blocking (ARB) drugs are the drugs of choice in patients with heart failure, chronic kidney failure (in diabetics or non-diabetics), or heart attack (myocardial infarction) that weakens the heart muscle (systolic dysfunction). Also, beta-blockers are sometimes the preferred treatment in hypertensive patients with a resting tachycardia (racing heart beat when resting) or an acute (rapid onset) heart attack.

Patients with hypertension may sometimes have a co-existing, second medical condition. In such cases, a particular class of anti-hypertensive medication or combination of drugs may be chosen as the first line approach. The idea in these cases is to control the hypertension while also benefiting the second condition. For example, beta-blockers may treat chronic anxiety or migraine headache as well as hypertension. Also, the combination of an ACE inhibitor and an ARB drug can be used to treat certain diseases of the heart muscle (cardiomyopathies) and certain kidney diseases where reduction in proteinuria would be beneficial.

In other situations, certain classes of anti-hypertensive medications should not be used. Dihydropyridine calcium channel blockers used alone may cause problems for patients with chronic renal disease by increasing proteinuria. However, an ACE inhibitor will blunt this effect. The non-dihydropyridine type of calcium channel blockers should not be used in patients with heart failure. However, these drugs may be beneficial in treating certain arrhythmias. Some drugs, such as minoxidil, may be relegated to second or third line choices for treatment. Clonidine is an excellent drug but has side effects such as fatigue, sleepiness, and dry month making it a second or third line choice. See the section below on pregnancy for the anti-hypertensive drugs that are used in pregnant women.

Which lifestyle modifications are beneficial in treating high blood pressure?

Lifestyle modifications refer to certain specific recommendations for changes in habits, diet and exercise. These modifications can lower the blood pressure as well as improve a patient's response to blood pressure medications.

Alcohol

People who drink alcohol excessively (over two drinks per day*) have a one and a half to two times increase in the prevalence of hypertension. The association between alcohol and high blood pressure is particularly noticeable when alcohol intake exceeds five drinks per day. The connection is a dose-related phenomenon. In other words, the more alcohol consumed, the stronger is the link with hypertension.

*The National Institute on Alcohol Abuse and Alcoholism considers a standard drink to be 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of 80-proof distilled spirits. Each contains roughly the same amount of absolute alcohol- approximately one-half ounce or 12 grams.

Smoking

Although smoking increases the risk of vascular complications (for example, heart disease and stroke) in people who already have hypertension, it is not associated with an increase in the development of hypertension. But cigarette smoking can repeatedly produce an immediate, temporary rise in the blood pressure of 5 to10 mm Hg. Steady smokers however, may have a lower blood pressure than nonsmokers. The reason for this is that nicotine in cigarettes causes a decrease in appetite, which leads to weight loss. This, in turn, lowers blood pressure.

Renal (kidney) hypertension

Diseases of the kidneys can cause secondary hypertension. This type of secondary hypertension is called renal hypertension because it is caused by a problem in the kidneys. One important cause of renal hypertension is narrowing (stenosis) of the artery that supplies blood to the kidneys (renal artery). In younger individuals, usually women, the narrowing is caused by a thickening of the muscular wall of the arteries going to the kidney (fibromuscular hyperplasia). In older individuals, the narrowing generally is due to hard, fat-containing (atherosclerotic) plaques that are blocking the renal artery.

How does narrowing of the renal artery cause hypertension? First, the narrowed renal artery impairs the circulation of blood to the affected kidney. This deprivation of blood then stimulates the kidney to produce the hormones, renin and angiotensin. These hormones, along with aldosterone from the adrenal gland, cause a constriction and increased stiffness (resistance) in the peripheral arteries throughout the body, which results in high blood pressure.

Renal hypertension is usually first suspected when high blood pressure is found in a young individual or a new onset of high blood pressure is discovered in an older person. Screening for renal artery narrowing then may include renal isotope (radioactive) imaging, ultrasonographic (sound wave) imaging, or magnetic resonance imaging (MRI) of the renal arteries. The purpose of these tests is to determine whether there is a restricted blood flow to the kidney and whether angioplasty (removal of the restriction in the renal arteries) is likely to be beneficial. However, if the ultrasonic assessment indicates a high resistive index within the kidney (high resistance to blood flow), angioplasty may not improve the blood pressure because chronic damage in the kidney from long-standing hypertension already exists. If any of these tests are abnormal or the doctor's suspicion of renal artery narrowing is high enough, renal angiography (an X-ray study in which dye is injected into the renal artery) is done. Angiography is the ultimate test to actually visualize the narrowed renal artery.

A narrowing of the renal artery may be treated by balloon angioplasty. In this procedure, the physician threads a long narrow tube (catheter) into the renal artery. Once the catheter is there, the renal artery is widened by inflating a balloon at the end of the catheter and placing a permanent stent (a device that stretches the narrowing) in the artery at the site of the narrowing. This procedure usually results in an improved blood flow to the kidneys and lower blood pressure. Moreover, the procedure also preserves the function of the kidney that was partially deprived of its normal blood supply. Only rarely is surgery needed these days to open up the narrowing of the renal artery.

Any of the other types of chronic kidney disease that reduce the function of the kidneys can also cause hypertension due to hormonal disturbances and/or retention of salt.

It is important to remember that not only can kidney disease cause hypertension, but hypertension can also cause kidney disease. Therefore, all patients with high blood pressure should be evaluated for the presence of kidney disease so they can be treated appropriately.

Cholesterol Levels Vary Widely by Country: Study

MONDAY, April 9 (HealthDay News) -- People's average cholesterol levels seem to rise and fall along with their countries' economies and ease of access to quality health care, according to a new study.

Researchers examined data from thousands of patients with a history of high cholesterol (more than 200 milligrams per deciliter) in 36 countries, including the United States.

The analysis revealed that countries with higher overall income levels, lower out-of-pocket health care costs, and high-performing and efficient health systems tend to have lower rates of high cholesterol among people who'd had a history of high cholesterol.

For patients with no history of high cholesterol, there was no association between a country's economy and health care system and the risk of high cholesterol.

Among the specific findings:

Rates of total high cholesterol varied widely, ranging from 73 percent in Bulgaria to 24 percent in Finland.

Rates of elevated cholesterol levels in patients were particularly high in the following Eastern European countries: Bulgaria, Lithuania, Romania, Ukraine, Hungary and Russia. These countries also scored relatively low in terms of their economies and health systems.

The United States' rate of people with elevated cholesterol levels was similar to that of other developed countries -- such as Australia, Canada, Finland, Israel and the United Kingdom -- but U.S. spending on health care was considerably higher than other developed countries.

The study appears April 9 in the journal Circulation.

The optimum management of heart disease is difficult, and differences in rates of high cholesterol between nations "may be due to differences in clinical guidelines, as well as whether and the extent to which guidelines are followed and specific initiatives are effectively implemented," lead author Elizabeth Magnuson, director of the Health Economics and Technology Assessment at Saint Luke's Mid America Heart Institute in Kansas City, Mo., said in a journal news release.

She added that the association between high out-of-pocket health care costs for patients and their higher cholesterol levels "may reflect an inability or unwillingness" among these patients to take the medicines they've been prescribed. However, "the recent availability of generic cholesterol-lowering therapy should make out-of-pocket expense less of a barrier," Magnuson noted.

Source:medicinenet.com