What is blood pressure?

Blood pressure plays a vital role in the way the heart delivers fresh blood, containing oxygen and nutrients required throughout the body. To get the blood to go that far, fast enough, it has to be under pressure. This pressure is created by the relationship between three things:

– the heart’s pumping action
– the size and stretchiness of the blood vessels
– the thickness of the blood itself

Blood pressure can be compared to a central heating system. Three vital components work together to make the system work: the boiler (heart), the pipes (blood vessels) and the hot water (blood). The radiators are the different organs and parts of the body

In order for the same amount of heat to be delivered to the farthest away radiator, the boiler has to send the water out under pressure. The size of the boiler will affect this pressure, as will the size of the pipes (or blood vessels)

Blood vessels have a layer of muscle within their walls, which makes them able to widen or narrow depending on how much blood each part of the body requires

How is blood pressure measured?

To find out your blood pressure, two measurements are recorded during a single heartbeat:

– the level of pressure when your heart pumps blood through your arteries and around your body (systolic pressure): this is when the pressure is highest, and

– the level of pressure when your heart is resting before it pumps again (diastolic pressure): this is when the pressure is lowest

Blood pressure is measured in millimetres of mercury (mmHg). The readings are given as two numbers or levels. The systolic reading is first, followed by the diastolic reading. For example, if your systolic reading is 120mmHg and your diastolic reading is 80mmHg, your blood pressure is 120 over 80. This is commonly written as 120/80

Blood pressure – high, normal or low?

Blood pressure can be high, normal or low

If you consistently have a reading of 140/90 or higher, you may have high blood pressure (hypertension). High blood pressure increases your risk of developing some health conditions, including cardiovascular disease

Generally, the lower your blood pressure, the healthier you are. As a general guide, the ideal blood pressure for a young healthy adult is 120/80 or lower. However, it’s possible to have abnormally low blood pressure

People with a reading of around 90/60 or lower are generally considered to have low blood pressure. For some people with low blood pressure, there may be an underlying cause that could need treatment

What is high blood pressure (hypertension)?

If you have high blood pressure, the force that your heart uses to pump blood around your body is higher than ideal. Your blood pressure is high if your blood pressure reading is consistently 140/90 or higher

No obvious symptoms

High blood pressure doesn’t usually have any obvious symptoms. The only way to find out if you have high blood pressure is to get your blood pressure checked regularly. It’s a startling fact that around 40% of the people who have hypertension don’t know about it!

Risks of high blood pressure

Having high blood pressure means that your heart has to work harder to pump blood around your body. Over time, this can weaken your heart. The increased pressure can also damage the walls of your arteries, causing them to be blocked or an artery to split.

High blood pressure increases your risk of developing cardiovascular disease (CVD), for example:

– coronary heart disease: the main arteries that supply your heart become clogged up with fatty deposits
– stroke: where the blood supply to your brain is interrupted
– heart attack: where the blood supply to your heart is blocked

Treating high blood pressure

Treatment for high blood pressure depends on:

– the level of your blood pressure, and
– your risk of developing CVD

If your blood pressure is only slightly higher than ideal and your risk of CVD is low, you will more than likely be able to lower it by making changes to your lifestyle, such as:

– eating more healthily
– exercising more regularly
– drinking less alcohol

However, if your blood pressure is much higher than ideal and your risk of CVD is higher, you may also be prescribed medication

What is low blood pressure (hypotension)?

Low blood pressure is a condition where the pressure in your arteries is abnormally low. It means that the force your heart uses to pump blood around your body is lower than ideal. Your blood pressure is considered to be low if your blood pressure reading is around 90/60 or lower

Does low blood pressure have symptoms?

On its own, low blood pressure does not always cause symptoms

However, low blood pressure can sometimes mean that there is not enough blood flowing to your brain and other vital organs, which can lead to symptoms such as:

– dizziness
– fainting (a sudden, temporary loss of consciousness)
– lightheadedness
– blurred vision
– a rapid, or irregular heartbeat (palpitations)
– confusion
– feeling like you’re going to be sick (nausea)
– general weakness

Low blood pressure can have many causes

Many everyday factors can affect your blood pressure and, in some cases, cause it to be low. For example, the time of day and if you’ve recently eaten

If your blood pressure is still considered low after taking into account everyday factors, there are many other possible causes.Some types of medication, such as beta blockers, may cause low blood pressure. Other causes include dehydration, autonomic disorders such as Parkinson’s disease, damage to your adrenal glands, serious injury and shock, prolonged bed rest and increasing age

Treating low blood pressure

If you have low blood pressure but no symptoms, you don’t need treatment

If you do have symptoms, your GP will try to find the cause and assess whether treatment will help. They will also give you advice to help limit your symptoms. Few people are prescribed medication for low blood pressure