High blood pressure
High blood pressure is a condition in which the pressure of the blood pumping through the arteries is abnormally high. This increases the risk of stroke, aneurysm, heart failure, heart attack and kidney damage.
A blood pressure reading consists of two numbers:
• Systolic pressure, which indicates the contraction of the heart muscle
• Diastolic pressure (the second number) measures the blood pressure when the heart relaxes between beats
A reading of 140/90 or higher qualifies as high blood pressure. An ideal blood pressure reading is 120/80. However, blood pressure varies throughout a lifetime. Children have much lower blood pressure than adults. As people grow older, their blood pressure rises. In general, readings are higher in the morning and lower while a person sleeps. Physical activity makes blood pressure go up, and rest causes it to go lower.
Symptoms of high blood pressure
Hypertension is often called the "silent killer" because symptoms of high blood pressure may not appear for years until a vital organ is threatened. Signs of long-untreated high blood pressure (such as headache, fatigue, nausea, vomiting, shortnessof breath, restlessness and blurred vision) can be the result of damage to the brain, eyes, heart and kidneys.
Causes of high blood pressure
In most cases, the causes of high blood pressure are not known. In some cases, diseases cause blood pressure to increase. These include:
- Atherosclerosis, which makes arteries stiff and unable to widen in response to rising blood pressure
- Cushing's syndrome, which involves an overactive thyroid gland or a tumour in an adrenal gland
- Kidney diseases or injury
- Rare causes such as phaeochromocytoma and Conn’s syndrome.
The risk of high blood pressure is greater for those who are:
- A smoker
- Of African origin
- Older. About 75% of women and almost 66% of men aged 75 or older have high blood pressure. (Only about 25% of people between the ages of 20 and 74 have high blood pressure.)
- Overweight. High blood pressure occurs twice as often in people who are obese as it does in people who are not.
- Under stress
Diagnosing high blood pressure
High blood pressure is often discovered during a routine visit to the doctor. Blood pressure is measured after sitting or lying down for about five minutes. It may be measured again after you have been standing for a few minutes.
Blood pressure readings can vary widely and it may take several readings to confirm a diagnosis. In cases where there is doubt, a 24-hour blood pressure monitor can be used (see tests).
Tests may be recommended:
- An electrocardiogram (ECG)
- Blood tests
- A urine test to check for signs of kidney damage
It may be necessary to examine your retina at the back of the eye. This is one place where the effects of high blood pressure on the blood vessels can be seen.
Treating high blood pressure
If an underlying disease or condition has been identified as the cause, treatment of high blood pressure will focus on that condition. When it has been brought under control, your high blood pressure may go away.
Before using drugs to control high blood pressure, most doctors will suggest:
- Reducing alcohol
- Reducing salt in the diet
- Exercising regularly
- Losing weight
- Stopping smoking
If these approaches are not effective, daily drugs to lower blood pressure may be needed. The most commonly used drugs for the treatment of high blood pressure, include:
- Diuretics to reduce excess salt and water
- Angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARB) to dilate the arteries and relieve pressure
- Calcium-channel blockers, which cause blood vessels to widen using a different mechanism
Because drugs to lower high blood pressure work in different ways and have different effects, it may be necessary to try different drugs or combination of drugs.