Understanding blood pressure

Blood pressure is the pressure of your blood on the walls of your arteries as your heart pumps it around your body. It naturally goes up and down often during the day, depending on what you are doing – such as when you’re exercising or sleeping.

If you’ve ever had your blood pressure checked, you will know that there are two numerical readings, usually presented as a fraction – e.g. 120/75 mmHg. The top number is always the higher one. It is called the systolic blood pressure, and it is higher than the bottom number because it’s indicating the blood pressure when your heart is contracting (squeezing) the blood out to the arteries. Whereas the smaller number, your diastolic blood pressure, measures the pressure in your arteries when your heart is relaxed – i.e. when it is filling up with blood.

Millimetres of mercury (mmHg) is simply the unit in which blood pressure is measured.

Okay, so which number is more important – the top (systolic) or bottom (diastolic)?

Usually the top number (the systolic blood pressure) carries greater significance when it comes to indicating cardiovascular (heart and blood vessel) disease in people over the age of 50.

Overall, systolic blood pressure generally rises steadily with age. This is usually because of increasing stiffness of large arteries, build-up of plaque over the years, and increased incidence of cardiac and vascular disease.

So, what is normal blood pressure?

According to the Heart Foundation, a blood pressure reading under 120/80mmHg is considered optimal. Readings over 120/80mmHg and up to 139/89mmHg are in the normal to high-normal range.

Your chances of having persistently high blood pressure increases as you age.

What happens if you have high blood pressure?

High blood pressure is when your blood pressure is consistently higher than normal. It is medically known as ‘hypertension’. The concern with having hypertension for a considerable time is that it is one of the main factors for developing heart disease, which can lead to heart attack or stroke. Hypertension may also damage your kidneys.

What affects your blood pressure?

The exact cause of high blood pressure is not always clear. Your risk of having high blood pressure increases if you:

  • have a family history of high blood pressure
  • eat unhealthily, including salty foods
  • consume too much alcohol
  • are overweight
  • don’t do enough physical activity.

Certain medicines can also raise your blood pressure.

What can you do to look after your blood pressure?

The main way to keep your blood pressure in the healthy range is through diet and lifestyle – i.e. eating well and exercising. If this does not help to control your blood pressure, your doctor may prescribe you blood pressure medicines. It’s important to realise that blood pressure medicines don’t cure high blood pressure. So you have to keep taking them daily – as well as continue with a healthy lifestyle ­– to control your blood pressure, often for the rest of your life.

Blood pressure doesn’t have any symptoms, so it’s best to get it regularly checked with your doctor. If you have hypertension, your doctor will be able to advise you of the optimal way to control it.

Read more at Heart Foundation.

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