It is generally considered that the life insurance offices hold the world’s most accurate statistical evidence on the outcome of hypertension. Most houses now use these figures, and in recent years, the 135/85 upper level has been in increasing use.
Life-insurance companies are in business to make money, and the voluminous statistics they have been keeping for many years bear testimony to the significance of blood pressure beyond these levels. In short, clients with elevated levels simply die sooner than those with “normal” levels.
However, there is a very wide range in subjects who appear healthy. Anything from 100 to 140 systolic, over 60 to 90 diastolic is frequently considered the normal range. “The normal is about 125/75, and a figure of 140/90 in an otherwise healthy adult may be taken as the upper limit of normal,” one major textbook writer suggests.
As has been already explained, the systolic pressure represents the blood-pressure reading when the heart muscle contracts, forcing blood from the left ventricle into the aorta and arterial system. The diastolic pressure is the one that persists when the heart is at rest between successive beats. It is now well recognized that the diastolic pressure is the more significant of the two. If this is persistently elevated, then the outlook becomes more serious.
The pressure is measured by an instrument called a sphygmomanometer. It is taken usually on either of the arms, and recorded in terms of millimeters of mercury, usually expressed “mm 11g.” Or more simply, the pressure is written 140/90, or whatever the figures are.
Doctors are gradually changing over to a new form of recording BPs. Instead of mm, the term kilopascal is being used. More will be heard of this, the so called SI System, in the future.
Blood pressure tends to increase gradually with advancing years, when there is a normal decrease in the general elasticity of the arterial walls. Transient variations, possibly of 20 or 30 points, are common with various states and emotional and physical situations. Nervousness, excitement, exertion, fatigue, cold and smoking, all tend to elevate readings. Most are transient, and reduce rapidly. Smoking has been found to have a profound, long-term effect on the blood-vessel walls and also the pressure, and is a serious cause of permanent elevation.
Anything that produces tension in the blood vessels peripherally can aggravate blood pressure, and the nicotine of the cigarette can have this effect, causing constriction, and hence resistance to normal blood flows. This may be transmitted hack to the heart, where long-term difficulties are encountered.
Normal Blood Pressure Symptoms
Generally speaking, benign hypertension is symptomless. It may be present for many years, the patient being completely unaware of its existence. Very often, it is discovered inadvertently, probably through a general check-up for health, or at an examination for life-insurance purposes.
Sometimes, symptoms claimed to be due to blood pressure are described, including headaches, giddiness, nervousness and palpitations. These may be due to the pressure itself, or perhaps they are part of an overall anxiety due to the knowledge that there is pressure present, or to the fact that there is a family history suggesting this. Many women in the menopausal years find such symptoms common, and it is a puzzle to know which to ascribe to a general reduction in hormonal production, and which to attribute to hypertension.
Some patients have a definite tendency to headaches, and these seem more likely in the morning. They may awaken the patient, and may be severe and seemingly intractable throughout the day. They seem more likely to occur in women with a tendency to migraine. They may even be associated with nausea and vomiting. Sometimes they respond to migraine type therapy.
In many patients, the first indication of elevated pressure is when complications set in. A common symptom is the appearance of breathlessness (dyspnoea) with exertion. This indicates that the heart muscle has become involved, and is now working at a reduced level of efficiency, and symptoms are those of early congestive cardiac failure. Blurring of the vision may indicate damage to the vessels of the eye; sudden blindness or partial loss of vision has the same implication.
Severe cerebral symptoms may occur. They range from sudden death from a hemorrhage or thrombus formation (which may jam a vital vessel), to double vision, loss of the ability to talk, isolated paralysis (for example, of part of the face) to a more widespread type, such as a quarter or half of the body being involved. The variations are numerous. With the progression of time, and if the cerebral vessels are affected by arteriosclerosis, gradual diminution of mental acuity can take place. This may deteriorate until a state of dementia ensues. Many intermediate stages can occur during this process.
Examination of the “midi” of the eyes (part of the retina) will indicate various degrees of so-called “hypertensive retinopathy,” as has already been described. The findings in this area can have implications as to the future outcome, and the level of severity.