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High blood pressure – facts and myths

By DR THOMAS KAISER [email protected]

Dr Thomas Kaiser is the Medical Director of the Vale do Lobo Medical Centre and is a specialist in good traditional General Practice for the whole family, state of the art aesthetic and cosmetic medicine.

High blood pressure is one of the most common dangerous illnesses of modern society. It is an important risk factor for the development of heart attacks and strokes. It is also detrimental for your blood vessels in general, your kidneys and your eyesight.

There are many myths circulating about the meaning and cause of high blood pressure. I will therefore try to explain the essential facts about blood pressure (BP).

With BP we mean the physical pressure in arteries, not veins. The BP is a dynamic figure and depends on several variables. Blood pressure tends to be higher when you are up and active, stressed or worried, angry or excited. It is lower when we are asleep, relaxed and tired.

The most accurate way of measuring it is by inserting a pressure probe into an artery. This method is used during operations by anaesthetists. As you can imagine, this is not a method suitable for the daily work in the doctor’s office or the pharmacy. Therefore, an indirect method is used by applying pressure through a cuff to the artery in the elbow crease until it is completely blocked. The pressure that is needed to do that is called ‘systolic pressure’. This pressure is by definition the pressure in the arteries when the heart pumps blood full force into the circulation.

The doctor then releases the pressure and measures it when the artery is fully open again. This pressure is called ‘diastolic pressure’. By definition, this is the pressure when the heart is being filled passively with blood before the next contraction can take place.

You will get readings like 130/70 mmHg. The origin of the unit mmHg comes from the method that was used in the beginning, when the pressure was assessed in columns with Hg (chemical symbol for mercury). In Portugal, the units are not mmHg but cmHg, giving you readings like 13,0/7,0.

Blood pressures up to 145/85 are considered normal. There is a gray area up to 160/90, when real high blood pressure starts. There are various classifications distinguishing between light, moderate, severe and critically high BP. A hypertensive crisis is defined by BPs of higher than 200/100 with symptoms like headaches, visual disturbance and confusion.

I find these classifications not very helpful. The fact is, the higher the BP the worse for your blood vessels. The mechanism of how the level of pressure damages your blood vessels is probably through the effect of chronic overpressure that will also eventually destroy the  pipes of your heating system, if you run it consistently with too much pressure.

Does cholesterol affect blood pressure?

No, there is no direct relationship between your cholesterol levels and your BP. Both are independent risk factors for heart disease and strokes and if both are up, it is particularly bad news for your blood vessels.

Can the BP be different between the left and right arm?

Yes, it could be. The best method is to measure initially on both arms. The arm with higher pressure should be chosen for the continuous monitoring.

Can blood pressure be too low?

Yes, if the BP is below 100/60 or so, some people will be prone to feeling giddy, tired and weak.

Dehydration, blood loss, excess heat and being young and female can be the cause.

Which reading is more important, the systolic or the diastolic BP?

Both readings are equally important. The diastolic pressure tends to be the more constant figure, while the systolic goes up quicker under stress or exertion.

What is the cause of blood pressure?

About 90 per cent of cases of hypertension are not caused by one particular reason. The cause is ‘multifactorial’, meaning that several determinants like age, sex, genetics, weight, lifestyle, diet and exercise play a role. This form of hypertension is also called ‘essential hypertension’.

The remaining 10 per cent are caused by abnormalities of the kidneys or their blood vessels or rarely hormone producing tumours.

What are the symptoms of high blood pressure?

Unfortunately moderate high BP causes little symptoms, which is why it often goes missed. If the blood pressure is very high it can cause headaches, nosebleeds, palpitations and chest pains.

What tests should be done if high BP has been detected?

High BP should never be diagnosed by measuring during one occasion. At least six measurements on three occasions should be used. The gold standard test is a 24 hour BP assessment, which is reflecting the BP profile under normal daily living circumstances. That test is called MAPA in Portugal.

If blood pressure was established as too high, you should have basic blood and urine tests, an ECG, echocardiogram, scan of the kidneys and a thorough examination by an eye specialist.

Do I always need to take tablets if I was diagnosed with high BP?

No, if the BP is not very high, it is possible to try lifestyle modifications.

There are six things you should implement:

1. Do not smoke

2. Reduce weight

3. Reduce salt intake

4. Reduce alcohol consumption

5. Reduce stress

6. Increase aerobic exercise

If I was started on medication, do I have to take it for the rest of my life?

No, once the blood pressure is reduced significantly and you have changed lifestyle factors, one can reduce or even stop medication. In the majority of cases, though, the patient will go undertreated and not the opposite.

What is the rule of 50s in high BP management?

This rule of 50 per cent reflects the fact that 50 per cent of patients with high blood pressure are never diagnosed. Of the 50 per cent that are diagnosed, 50 per cent go untreated. Of the 50 per cent that receive treatment, only 50 per cent are treated to a satisfactory level of BP. This rule was used in the UK to enforce more emphasis on good BP management in primary care. Your GP will now be very keen for you to be ‘measured’ every year. The days when high blood pressure was trivialized are finally over which is good because high blood pressure is a silent killer.

How often should I have my BP checked, if it is normal?

A good sensible policy is to have it checked every year. If you are hypertensive you should probably get a machine to self monitor your BP. If you buy one, go for the machines with upper arm cuff.

For more information, please call Dr Kaiser on 289 398 009.