ABC of Vascular Disease

High blood pressure (hypertension)

1. What is blood pressure?
The blood pressure in the arteries is what drives the blood around the body.  The blood pressure is generated by the pumping action of the heart and the blood pressure goes up as the heart beats and goes down between the beats.  The blood pressure varies between the higher pressure (called the systolic pressure) and the lower pressure (called the diastolic pressure).  The body regulates the average blood pressure so that it is kept above a certain level to ensure that enough blood will flow and below a certain pressure to prevent damage to the heart and arteries.  The blood pressure is affected by a number of separate factors: the heart, the state of the large arteries and the size of the small arteries.   Your blood pressure changes from minute to minute depending on what you are doing: it is lowest during sleep and highest during stressful situation and exercise. These changes are normal and do not indicate a problem.  As you get older your arteries get stiffer and the systolic pressure tends to increase.

2. What is hypertension?
Hypertension is high blood pressure.  Most patients with hypertension have no obvious cause (essential hypertension).  A few have an underlying cause (secondary hypertension) which if treated will usually also cure the hypertension.

3. What problems does hypertension cause?
Hypertension causes a number of problems including heart, brain and kidney damage, and damage to the delicate lining of the arteries.  Hypertensive patients are more likely to development of occlusive and aneurysmal arterial disease and will aggravate other risk factors such as smoking, and diabetes.  Hypertensive patients have a higher risk of strokes and heart attacks.

4. How is hypertension diagnosed?
Simply by measuring the blood pressure using a cuff around the arm and a stethoscope to listen over the artery.  As blood pressure is normally quite variable is is necessary to have a number of abnormally high readings before hypertension can be diagnosed with confidence.  Some patients feel anxious when they see a doctor to have their blood pressure measured and this may give an incorrectly high reading (white coat hypertension).  Sometimes it is necessary to measure the blood pressure repeatedly over a period of time to get a reliable estimate and this can be done by wearing a portable, automatic blood pressure machine (ambulatory blood pressure).  Other tests may be done to assess if hypertension has caused damage (e.g electrocardiogram, chest x-ray, blood test) of if it is secondary to another problem.

5. How is hypertension treated?
In mild cases a change of diet may be all that is required to bring down the blood pressure (e.g. too much alcohol increases blood pressure). Daily drugs are required if the hypertension is more severe.  Which drug is used depends on the degree of hypertension and any co-existing medical problems.  There are flour main classes of drug used to treat hypertension:

These different types of treatment are additive so treatment of hypertension usually starts with low doses of one drug.  If the hypertension is resistant to this treatment the doses are increased and/or different drugs used together. Patients on treatment for hypertension should have their blood pressure checked to ensure the treatment is effective. Patients should not alter the dose of their anti-hypertensive drugs without advice from their doctor.

6. Is there a cure for hypertension?
Unfortunately not, unless the hypertension is secondary to another problem.

7. How effective is the treatment?
Large clinical trials have shown that patients with hypertension are at lower risk of complications such as strokes if the high blood pressure is controlled.  Treatment of hyperlipidaemia does not guarantee complete immunity to complications, instead it reduces the likelihood of having a complication.

© S.R.Dodds 2001