The facts we’ve come up with may help the many people suffering hypertension. For the healthy, they highlight the risk factors that too many of us ignore.
What exactly is blood pressure?
Blood pressure is the force of the blood pumped from the heart against the walls of the arteries.
Doesn’t everybody have blood pressure?
Yes. Everybody must have a certain level of blood pressure to maintain circulation. But if, for any reason, the pumping action of the heart gets faster or the resistance of the blood vessels increases, blood pressure tends to rise.
How does the circulation system work?
The circulation (the cardiovascular system) consists of a pump – the heart – and two circuits. The blood goes along the aorta, the large blood vessel or “great artery” leading from the heart. Other arteries branch out from the aorta. The blood vessels divide into small blood vessels called the capillaries, which link with the veins. This is how the blood is collected and returned to the heart where the cycle starts again.
What part do the two circuits play in the cardiovascular system?
In one circuit, the pulmonary, the blood which is returned to the heart is pumped through the lungs where it absorbs oxygen. The blood then returns to the heart and is pumped to the rest of the body in the second circuit, known as the systemic circulation. For the cardiovascular system to work efficiently, the pump, or heart, must work efficiently and the arteries carrying blood to the rest of the body must be clear and healthy.
How is blood pressure measured?
The doctor measures the pressure of the blood on artery walls with a Blood-Pressure Monitor. This is a rubber cuff connected by a tube to a column of mercury and bellows. The cuff is wound round in the middle of the upper arm and the doctor listens through a stethoscope to the pulse of the artery just in front of the elbow.
He inflates the cuff until the arterial pulse is no longer heard and then releases the pressure until the artery pulse is again heard pumping. The number of millimeters of pressure when the heart contracts and blood is forced into the aorta is recorded on the mercury column. This is known as the resting systolic pressure.
Now, air pressure is released until the pulse is quiet, and a second reading, the diastolic pressure, is recorded on the mercury column. This reading records the pressure when the heart relaxes between contractions and its cavities are dilated by the blood flowing into them.
In healthy young adults, resting systolic pressure is usually about 120mm and the diastolic pressure about 80mm but blood pressure tends to fluctuate, even in the young, and may sometimes be elevated due to some trauma, for example an emotional upset. The condition usually rights itself unless the cause is a disease, such as a kidney disorder, when further investigation is necessary.
As one grows older, blood pressure gradually increases. If the reading is consistently over 160mm systolic pressure and over 90mm diastolic pressure, the patient is said to be hypertensive. The most usual type of high blood pressure is called “essential hypertension”.
What is the cause of essential hypertension?
In 95 percent of cases, doctors can’t find a cause although there is a probable genetic factor. There are indications of some imbalance in one of the hormone systems that tends to potentiate hypertension by retaining salt in the body. There are indications, too, of some change in the sympathetic nervous system response that may be mediated through the brain, causing elevated blood pressure.
Are blood pressure measurements always accurate?
Blood pressure fluctuates. The problem with measuring blood pressure is that the reading may not be a summary of what is happening in the course of the 24-hour cycle. If the pressure is elevated, patients should lie down for 5 minutes or so, then repeat the procedure.
Are there any other methods of assessing blood pressure?
Yes. Since hypertension affects blood vessels, doctors look at the vessels at the back of the eyes. Changes in the retinal arteries give them a good idea of how severe the hypertension may be.
Severity of hypertension can also be assessed by looking at an electrocardiogram (ECG) which may show damage or increased thickness of the heart due to the extra load placed on it.
What happens if these tests suggest moderate to severe hypertension?
The patient is further investigated. Kidneys are checked in case the condition is due to renal hypertension. Electrolytes (minerals in the body) must be checked because an imbalance between sodium and potassium metabolism (a hormone imbalance) may cause really severe hypertension. Occasionally, the cause of elevated blood pressure is some unusual congenital defect but this is rare.
Do very many people develop severe hypertension?
Not all that many. Most hypertension is moderate or mild but it must be identified and treated. A few patients develop severe hypertension (“malignant hypertension”). It has a rapid onset and it is difficult to treat. At one time it was considered fairly lethal but today even severely affected patients can be treated.
Is hypertension inherited?
There appears to be a factor that predisposes people to hypertension and that is inherited but we can’t do anything about our genes. What we can do is to be aware of factors that are known to aggravate hypertension.
What are the high-risk factors?
- heavy drinking
- high blood cholesterol
- excessive salt intake.
- lack of physical exercise (common in the overweight)
Smoking is an important factor because hypertension in itself, together with smoking and high cholesterol, is a very major risk factor in the development of arteriosclerosis.
Why is smoking so harmful?
Smoking may cause increased hardening of the arteries (arteriosclerosis). It may affect the muscles of the heart or induce clotting in the blood. Smoking may not be an actual cause of high blood pressure but it is known that malignant hypertension is more common in smokers than in non-smoker. Smokers with high blood pressure are at high risk.
Why is it that obesity aggravates hypertension?
Obesity contributes to the narrowing and hardening of the arteries. Fat people are more at risk of stroke and coronary heart disease than people of average weight.
Obesity is a strain on the heart, because the continuously working pump has to work extra hard providing blood to unwanted, fatty tissue. It has been proved that fat people have a shorter life expectancy than thin people. It has also been shown in several studies that people with high blood pressure who lose weight need less medication.
What is high cholesterol?
A high cholesterol level can arise when fatty substances carried around the body in the blood stream produce abnormally high blood-fat levels. In some cases this runs in families.
Foods containing saturated fats from animals may raise the level of cholesterol in the blood. Foods high in cholesterol are dairy produce (milk, butter, cream, ice cream, cheeses, egg yolk), shellfish, duck, goose and meats (trim fat off all meat), pastry, lard and suet.
Another group of fatty substances are found in carbohydrate foods containing sugars. This does not mean that carbohydrates should be avoided. They are a source of essential energy.
What you should avoid is sugar. Raw or refined, it has no (or very little) nutritional value and does nothing for fat people but make them fatter. Avoid sweets, cakes, pastries, ice cream, sweet cordials and alcohol, especially beer. Most food contains natural sugar and it is unnecessary to add sugar to tea, coffee or fruit.
Necessary carbohydrates for energy can be obtained from cereals, wholemeal bread, potatoes, beans, peas, lentils and pasta (preferably the wholemeal variety). These foods contain fiber, and while they fill you up, their calorie content is comparatively low.
Some doctors believe that the low-fiber content of our western diet is to blame for both cardiovascular diseases and bowel disorders. Coronary heart disease is far less common among people with a high-fiber diet and their blood pressures, too, are lower than those on a low-fiber, fatty diet.
Why is alcohol a risk factor?
There is no evidence that moderate drinking harms the cardiovascular system. Heavy drinking can harm the heart and circulation. It can cause weight gain. Another factor is that heavy drinkers are very often heavy smokers, too.
What are the symptoms of stroke?
A severe headache can be a warning, sometimes with tingling in a limb, clumsiness, difficulty in speech and mental confusion. But a stroke can occur without warning.
Anyone suffering these symptoms should seek medical attention immediately.
What is bypass surgery?
When a blockage in an artery is detected, surgeons can bypass the block by taking a vein from the leg and attaching it to the aorta, the main blood vessel coming from the heart. They virtually make this vein into another blood vessel. The technique is known as coronary bypass surgery.