heart and blood vessel disorders
High Blood Pressure
Diagnosis of High Blood Pressure
Measuring blood pressure For the most accurate readings, those that are used to diagnose someone with high blood pressure as opposed to a casual check, doctors follow a specific protocol when measuring blood pressure (see). Blood pressure is measured after a person sits for 5 minutes. The person must have had no exercise,caffeine, or smoking for at least 30 minutes before the measurement. A reading of 130/80 mm Hg or more is considered high, but a diagnosis cannot be based on a single high reading. Sometimes, even several high readings are not enough to make the diagnosis—because, for example, the readings may vary too much. If a person has an initial high reading, blood pressure is measured again during the same visit and then measured twice on at least two other days to make sure that the high blood pressure is still present. Several instruments can measure blood pressure quickly and with little discomfort. A sphygmomanometer is commonly used. It consists of a soft rubber cuff connected to a rubber bulb that is used to inflate the cuff and a meter that registers the pressure of the cuff. The meter may be a dial, digital meter, or a glass column filled with mercury. Blood pressure is measured in millimeters of mercury (mm Hg) because the first instrument used to measure it was a mercury column. When a sphygmomanometer is used, a person sits with legs uncrossed and back supported. An arm is bared (if a sleeve is rolled up, caution is needed to ensure that it is not tight around the arm), bent, and resting on a table, so that the arm is about the same level as the heart. The cuff is wrapped around the arm. Using a cuff that is proportional to the size of the arm is important. If the cuff is too small, the blood pressure reading is too high. If the cuff is too large, the reading is too low. Listening with a stethoscope placed over the artery below the cuff, a health care practitioner inflates the cuff by squeezing the bulb until the cuff compresses the artery tightly enough to temporarily stop blood flow, usually to a pressure that is about 30 mm Hg higher than the person's usual systolic pressure (the pressure exerted when the heart beats). Then the cuff is gradually deflated. The pressure at which the practitioner first hears a pulse in the artery is the systolic pressure. The cuff continues to be deflated, and at some point, the sound of blood flowing stops. The pressure at this point is the diastolic pressure (the pressure exerted when the heart relaxes, between beats). Some instruments can measure blood pressure automatically, without use of a stethoscope or rubber bulb. These devices may fit around the upper arm, finger, or wrist. For people older than 50, blood pressure measured at the upper arm is the most accurate. Sometimes a precise measurement of blood pressure is needed—for example, for a person in an intensive care unit. In such cases, a catheter can be inserted inside an artery to measure blood pressure directly. Instruments to measure blood pressure are available for home use by people who have high blood pressure. If there is still doubt, a 24-hour blood pressure monitor may be used. It is a portable battery-operated device, worn on the hip, connected to a blood pressure cuff, worn on the arm. This monitor repeatedly records blood pressure throughout the day and night over a 24-hour or 48-hour period. The readings determine not only whether high blood pressure is present but also how severe it is. Pseudohypertension,blood pressure that is measured as high when it is not, occurs in people with very stiff arteries (most commonly, older people). It occurs when the artery in the arm is too stiff to be compressed by the blood pressure cuff, and as a result, blood pressure cannot be measured accurately. occurs when blood pressure is measured as normal when it is high. Masked hypertension affects up to 10% of people who have high blood pressure. Recognizing this type of high blood pressure may be impossible unless blood pressure is measured at home or if a complication (for example, Heart Failure (HF) ) is suspected to have been caused by high blood pressure. After high blood pressure has been diagnosed, its effects on key organs, especially the blood vessels, heart, brain, eyes, and kidneys, are usually evaluated. Doctors also look for the cause of high blood pressure. The number and type of tests that are done to look for organ damage and to determine the cause of high blood pressure vary from person to person. In general, routine evaluation for all people with high blood pressure involves a Medical History and Physical Examination for Heart and Blood Vessel Disorders , a The physical examination includes checking the area of the abdomen over the kidneys for tenderness and placing a stethoscope over the abdomen to listen for a bruit (the sound caused by blood rushing through a narrowed artery) in the artery supplying each kidney. The retina in each eye is examined with an Ophthalmoscopy . The retina is the only place doctors can directly view the effects of high blood pressure on arterioles. The assumption is that the changes in the arterioles of the retina are similar to changes in arterioles and other blood vessels elsewhere in the body, such as in the kidneys. By determining the degree of damage to the retina ( A stethoscope is used to detect heart sounds. An abnormal heart sound, called the fourth heart sound, is one of the earliest changes in the heart caused by high blood pressure. This sound develops because the left atrium of the heart has to contract harder to fill the enlarged, stiff left ventricle, which pumps blood to all of the body except the lungs. Electrocardiography (ECG) is usually done to detect changes in the heart—particularly thickening (hypertrophy) of the heart muscle or heart enlargement. If enlargement is suspected, the person may undergo Kidney damage can be detected by urine and blood tests. Urine tests can detect early evidence of kidney damage. The presence of blood cells andalbumin(the most abundant protein in blood) in the urine may indicate such damage. People do not usually develop symptoms of kidney damage (such as lethargy, poor appetite, and fatigue) until much later, when much of kidney function has been lost. The higher the blood pressure and the younger the person, the more extensive the search for a cause is likely to be, even though a cause is identified in less than 10% of people. A more extensive evaluation may include x-ray, ultrasonography, and imaging of the kidneys and their blood supply as well as a chest x-ray. Blood and urine tests are done to measure the levels of certain hormones, such asepinephrine,aldosterone, andcortisol. The cause may be suggested by abnormal results of a physical examination or by the symptoms. For example, a bruit (an abnormal sound doctors hear with a stethoscope) in the artery to a kidney may suggest Blockage of the Renal Arteries (narrowing of the artery supplying a kidney). produced by a Pheochromocytoma . The presence of a pheochromocytoma is confirmed when the breakdown products of these hormones are detected in the urine. Other rare causes of high blood pressure may be detected by certain routine tests. For example, measuring the potassium level in the blood can help detect Hyperaldosteronism . 