What is High Blood Pressure?
High blood pressure or hypertension means high pressure (tension) in the arteries. The arteries are the vessels that carry blood from the pumping heart to all of the tissues and organs of the body. Hypertension does not mean excessive emotional tension, although emotional tension and stress can temporarily increase the blood pressure.
High blood pressure is generally defined as a level exceeding 140/90 mm Hg that has been confirmed on multiple occasions.
The systolic blood pressure, which is the top number, represents the pressure in the arteries as the heart contracts and pumps blood into the circulation. The diastolic pressure, which is the bottom number, represents the pressure in the arteries as the heart relaxes after the contraction. The diastolic pressure, therefore, reflects the minimum pressure to which the arteries are exposed.
Types of Hypertension or High Blood Pressure
Isolated Systolic Hypertension
Remember that the systolic blood pressure is the top number in the blood pressure reading and represents the pressure in the arteries as the heart contracts and pumps blood into circulation.
A systolic blood pressure that is persistently higher than 140 mm Hg is usually considered elevated, especially when associated with an elevated diastolic pressure (over 90). Isolated systolic hypertension, however, is defined as a systolic pressure that still is below 90. This disorder primarily affects older people and is characterised by an increased (wide) Pulse Pressure. The pulse pressure is defined as the difference between the systolic and diastolic blood pressure. And elevation of the systolic pressure without an elevation of the diastolic, as occurs in isolated systolic hypertension, therefore, increases the pulse pressure.
Once considered to be harmless an elevation of the pulse pressure is now thought to lead to future health problems. In other words, a high pulse pressure is considered an important precursor or indicator of potential end-organ damage. Thus, an isolated systolic hypertension is associated with a two to four times increased future risk, of an enlarged heart, a heart attack (Myocardial Infarction), a stroke (brain damage) and death from a heart disease or a stroke. Clinical studies in patients with isolated systolic hypertension have indicated that a reduction in systolic blood pressure by at least 20 mm to a level below 160 mm Hg reduces these increased risks.
White Coat Hypertension
What is White Coat Hypertension? A single elevated blood pressure reading in the doctor’s office can be misleading because the elevation may be only temporary. Presumably, such an elevation is caused by the patient’s anxiety that is related to the stress of the examination. In fact, the suggestion has been made that about one out of four people that are thought to have mild hypertension actually may have normal blood pressure when they are outside of the physicians office. This sort of elevated blood pressure, that is, an increase noted only in the doctor’s office, is called white coat hypertension. The name, of course, suggests that the white coat, which is symbolic for the physician, induces the patient’s anxiety and a passing increase in blood pressure. A diagnosis of white coat hypertension might imply that it is not a clinically important or dangerous finding.
However, caution is warranted in such an innocent interpretation of white coat hypertension. An elevated blood pressure that is induced by the stress and anxiety of a visit to the doctor may not necessarily always be a harmless finding. Other stresses in the patient’s life may likewise cause elevations in the blood pressure that are not ordinarily being measured. Accordingly, monitoring the blood pressure at home or at a pharmacy can help estimate the frequency and consistency of higher blood pressure readings. Additionally, conducting appropriate tests to research for any complication of hypertension can help evaluate the significance of variable blood pressure readings.
Borderline hypertension is defined as mildly elevated blood pressure that is found to be higher than 140/90 mm Hg at some time and lower than that at other times. In the elderly, a somewhat higher systolic blood pressure between 140 and 160 mm Hg is considered a borderline value, as long as the diastolic pressure is below 90. As in the case of white coat hypertension, patients with borderline hypertension need to have their blood pressure taken on several different occasions and their end organ damage assessed in order to establish whether their hypertension is significant.
We have to keep in mind that people with borderline hypertension may have a tendency, as they get older, to develop more sustained or higher elevations of blood pressure. Accordingly, they have a modestly increased risk of developing heart-related (cardiovascular) disease. Therefore, even if the hypertension does not appear to be significant initially, people with borderline hypertension should have continuing follow-up of their blood pressure and monitoring of the complications of hypertension.
If, during the follow-up of a patient with borderline hypertension, the blood pressure becomes persistently higher than 140/90 mm Hg, an antihypertensive medication is usually started, even if the diastolic pressure remains at a borderline level (usually under 90 mm Hg).