American Medical Association Family Medical Guide - American Medical Association [333]
• Enlarged heart High blood pressure makes the heart work harder. Over time, this extra effort causes the heart muscle to thicken. The heart becomes less efficient and has to work harder and harder to pump blood through the body, potentially leading to heart failure.
• Kidney damage The kidneys filter waste from the blood. Over time, high blood pressure can cause the blood vessels in the kidneys to narrow and thicken. The kidneys then filter less blood, and waste builds up in the bloodstream, sometimes leading to kidney failure. A person with kidney failure may need dialysis (a technique to remove waste from the blood) or a kidney transplant.
• Stroke High blood pressure can weaken the walls of the arteries or cause them to thicken. A weakened artery wall in the brain may break, causing a hemorrhage. A blood clot may block one of the narrowed arteries in the brain, causing a stroke.
• Eye damage High blood pressure can damage blood vessels in the eyes, causing them to thicken, narrow, or tear. This damage can lead to loss of vision.
Diagnosis
High blood pressure is usually detected during a routine checkup. When you visit your doctor, he or she will take a health history (see page 130), perform a physical examination, and measure your blood pressure. Because factors such as physical activity or stress can cause a temporary increase in blood pressure, your doctor will need to take a number of blood pressure readings over a period of several weeks or months to determine whether you have high blood pressure. If your blood pressure readings are occasionally above normal, your doctor may recommend that you monitor your blood pressure at home. If your blood pressure readings are consistently above normal, you have high blood pressure.
The doctor will probably examine your eyes with a viewing instrument called an ophthalmoscope. The condition of the blood vessels in the retina (the light-sensitive membrane that lines the back of the eyes) can provide valuable information about the extent of damage caused by high blood pressure.
Your doctor may perform additional tests to determine if you have essential hypertension or secondary hypertension. He or she may perform a chest X-ray (see page 109), an echocardiogram (see page 561), and an electrocardiogram (ECG; see page 559) to see if your heart is enlarged. The ECG will also reveal any previous damage to the heart muscle, such as damage caused by a heart attack. You will have blood and urine tests to determine if your kidneys are functioning properly. Some people may also need to have intravenous urography, a test in which the doctor injects a harmless dye into an artery and examines the kidneys on an X-ray image. Other people may have tests to evaluate blood flow, such as a CT scan (see page 562), an MRI (see page 113), a radionuclide scan (see page 114), or a coronary angiogram (see page 561).
A blood pressure reading of less than 120/80 mm Hg is generally considered normal. A category called prehypertension—120-139/80-89—indicates that a person is at risk of eventually developing high blood pressure. Blood pressure is classified according to increasing level of health risk, as reflected in the guidelines on the next page.
Treatment
When the underlying cause of secondary hypertension is treated successfully, blood pressure usually returns to normal levels. However, if the underlying cause cannot be cured, treatment is usually the same as that for essential hypertension.
Lifestyle changes
For many people, lifestyle changes such as giving up tobacco, following a healthy diet, exercising regularly, losing weight, and managing stress not only decrease the risk of developing high blood pressure but also significantly reduce existing high blood pressure. However, if lifestyle changes do not lower blood pressure to within the normal range, the doctor will probably recommend treatment with