Determination of blood pressure yields two measurements: the systolic, which measures the height of the pressure produced by the thrust of the heart; and the diastolic, which measures the constant “head of pressure” that exists between the beats. A blood pressure of 120 for example, would record a normal systolic and a normal diastolic pressure.
Blood pressure may vary considerably in the same individual at different times in his life. It may show a rise under the influence of emotions, in cold weather, as an effect of drugs, and (sometimes) during the course of pregnancy. It may be lower in hot weather, when the person is resting or has taken sedatives, during a fainting spell, or as a result of shock. In contrast, it may also be remarkably stable from year to year.
The cutoff point at which high or low blood pressure is diagnosed is somewhat arbitrary and many people have borderline readings or may be somewhat high on one occasion and normal on another. Systolic blood pressure readings of less than 100 would be regarded as rather low for an adult; however, they are encountered in many perfectly healthy persons. In the diagnosis of high blood pressure or hypertension the diastolic blood pressure is of the greater importance. A diastolic blood pressure of 90-95 may be regarded as borderline elevation, and most doctors would agree that once it exceeds 100, high blood pressure exists. The diastolic blood pressure is more important because it represents a constant pressure to which the arteries are subjected. Thus a blood pressure reading of 130/100 might be regarded as a case of hypertension which should be treated, whereas one of 170/80 could well be regarded as normal, particularly for an elderly person,, and in any case not presenting a need for treatment.
Hypertension (High Blood Pressure) When levels of blood pressure significantly exceed normal, hypertension or high blood pressure is said to exist. A rise in blood pressure may occur acutely, as when a person is frightened, angry, or even as a result of the anxiety that some people are apt to experience when they go to the doctor’s office. On relaxation, such a person’s blood pressure may return to normal. A fairly sustained rise in blood pressure may occur throughout a pregnancy. with a return to normal soon after the delivery: this is often associated with an unusual degree of fluid retention and is thought to be due to secretions emanating from the pregnant uterus. Certain tumors of the adrenal glands known as pheochromocytomas may similarly produce secretions that raise the blood pressure, and there are many disorders of the kidney in which rises in blood pressure occur.
A great majority of cases of hypertension have no ascertainable causes of this sort and are spoken of as essential hypertension. Essential hypertension is found in about 20 per cent of the population and runs through some families, so that a constitutional factor seems to be involved. It is sometimes possible to identify individuals who will develop sustained hypertension later in life by abnormal rises in response to tension or to cold exposure, There are sound reasons for identifying and treating hypertension early in its course. Hypertension increases the work of the heart, the muscular wall of the left ventricle (whose contraction pumps out the blood) undergoing enlargement because of it. After many years of carrying the extra burden, the overworked heart muscle may fail, with resultant symptoms of shortness of breath due to lung congestion and such evidences of fluid retention (edema) as swollen ankles. The arteries everywhere show involvement: atherosclerosis and degenerative changes appear much earlier than usual, a sort of premature aging of the vascular system.
Circulatory problems are all increased in individuals with hypertension: they show an increased incidence of strokes, heart attacks, and kidney difficulties.
Treatment. A variety of drugs and treatments have now changed the whole course of hypertension. Depending on the severity of the hypertension and the patient’s response, various combinations of these drugs are employed. Among them are:
1. Rauwolfia derivatives- rauwolfia being the Indian root whose extract contains both tranquilizing and blood-pressurelowering properties. The purified derivatives include reserpine (Serpasil) and an agent called Singoserp. These drugs may be sufficient for mild cases of hypertension; if not, other drugs can he added to the treatment program.
2. Diuretic drugs-a number of drugs known collectively as the chlorothiazide drugs-promote the excretion of salt and water by the kidneys. For reasons still unknown this also serves to lower blood pressure, sometimes quite effectively. These drugs may be given daily, produce an obvious increase in the amount of urine, and are basic drugs in the treatment of hypertension.
3. Apresoline- a drug which has no other equivalent- apparently acts on the brain centers that control blood pressure levels. It is often combined with the preceding drugs.
4. Ganglionic-blocking agents-drugs that block the transmission of nerve impulses to the small arteries which are narrowed in hypertension, As these small arteries dilate, the blood pressure levels drop.