Hypertension

One of the key risk factors for cardiovascular disease is hypertension - or raised blood pressure. While raised blood pressure is a leading cause of heart attack and stroke, hypertension can be prevented or managed.

Hypertension refers to persistently high blood pressure. Blood pressure is created by the force of blood pushing against the walls of blood vessels (arteries) as it is pumped by the heart. The higher the pressure the harder the heart has to pump1.

Because it usually does not cause symptoms for many years, high blood pressure has been called the silent killer. If left uncontrolled, hypertension can lead to a heart attack, an enlargement of the heart and eventually heart failure. Blood vessels may develop bulges known as aneurysms and weak spots due to high pressure, making them more likely to clog and burst. The pressure in the blood vessels can also cause blood to leak out into the brain. This can cause a stroke. Hypertension can also lead to kidney failure, blindness, rupture of blood vessels and cognitive impairment.1

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How is hypertension defined?

Blood pressure is measured in millimetres of mercury (mm Hg) and is recorded as two numbers usually written one above the other. The upper number is the systolic blood pressure - the highest pressure in blood vessels and happens when the heart contracts, or beats. The lower number is the diastolic blood pressure - the lowest pressure in blood vessels in between heartbeats when the heart muscle relaxes.1

Hypertension is defined as a systolic blood pressure (SBP) of 140 mm Hg or more, or a diastolic blood pressure (DBP) of 90 mm Hg or more or taking antihypertensive medication.1

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What causes hypertension?

There are two types of high blood pressure.

Primary hypertension - for most adults, there's no identifiable cause of high blood pressure. This type of high blood pressure, called primary hypertension, tends to develop gradually over many years.2

Secondary hypertension - Some people have high blood pressure caused by an underlying condition. This type of high blood pressure, called secondary hypertension, tends to appear suddenly and cause higher blood pressure than does primary hypertension. Various conditions and medications can lead to secondary hypertension, including obstructive sleep apnea, kidney problems, adrenal gland tumours, thyroid problems, certain defects you're born with in blood vessels, certain medications and Illegal drugs.2

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Risk Factors2

High blood pressure has many risk factors, including:

Age - the risk of high blood pressure increases as you age.

Ethnicity - high blood pressure is particularly common among people of African heritage.

Family history - High blood pressure tends to run in families.

Being Overweight - the more you weigh the more blood you need to supply oxygen and nutrients to your tissues. As the volume of blood circulated through your blood vessels increases, so does the pressure on your artery walls.

Sedentary lifestyle - people who are inactive tend to have higher heart rates and the higher your heart rate, the harder your heart must work and thus there’s greater force on your arteries.

Smoking - smoking immediately raises your blood pressure temporarily and the chemicals in tobacco can damage the lining of your artery walls. This can cause your arteries to narrow and increase your risk of heart disease.

Too much salt - too much sodium in your diet can cause your body to retain fluid, which increases blood pressure.

Too little potassium - potassium helps balance the amount of sodium in your cells. If you don't get enough potassium in your diet or retain enough potassium, you may accumulate too much sodium in your blood.

Alcohol - heavy drinking can damage your heart and affect your blood pressure.

Stress - High levels of stress can lead to a temporary increase in blood pressure.

Chronic conditions - Certain chronic conditions may increase your risk of high blood pressure, such as kidney disease, diabetes and sleep apnea.

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Complications2

Uncontrolled high blood pressure can lead to complications including:

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    Heart attack, heart failure or stroke

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    Thickened, narrowed or torn blood vessels in the eyes - which can result in vision loss.

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    Aneurysm - If an aneurysm bursts, it can be life-threatening.

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    Dementia - narrowed or blocked arteries can limit blood flow to the brain, leading to a certain type of dementia (vascular dementia).

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    Weakened and narrowed blood vessels in your kidneys

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    Trouble with memory or understanding - Uncontrolled high blood pressure may also affect your ability to think, remember and learn.

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Treatment2

While lifestyle changes such as losing weight, regular exercise, quitting smoking and a healthy diet can help keep your blood pressure under control, you may also need medication. Treatment has to be tailored to the individual and it often takes some time to find the most appropriate treatment for your needs. The treatments are often complex and require extensive follow-up care as you may need combinations of medication. Your doctor might also need to change your treatment if it's no longer effective.

References:

1. Cardiovascular disease. A global brief on hypertension. World Health Organisation. 2018. http://www.who.int/cardiovascular_diseases/publications/global_brief_hypertension/en/ [accessed 29 Sep 2018]

2. High Blood pressure (hypertension). Patient Care & Health Information. Mayo Clinic.2018. https://www.mayoclinic.org/diseases-conditions/high-blood-pressure/symptoms-causes/syc-20373410 [accessed 29 Sep 2018]