24 hour Blood Pressure Monitoring

What is 24 hour Ambulatory Blood Pressure (BP) Monitoring?

A blood pressure monitor is used to measure and record your blood pressure over a 24 hour period during your normal daily routine. A small digital blood pressure monitor is attached to a belt around your waist and connected to a cuff around your upper arm.

What are the benefits of having 24hr BP monitor?

The 24hr BP monitor may help to

• establish a diagnosis of high blood pressure (hypertension)
• identify patients who have higher blood pressure readings when in the clinic (known as ‘white coat effect’)
• decide if blood pressure medication is required
• decide whether any change to your medication is required
• how well a patient’s blood pressure medicines are controlling blood pressure throughout the day

How do I prepare for the test?

You’ll need to wear something with loose sleeves so that we can put a blood pressure cuff on your upper arm. The monitor itself will be attached to a belt around your waist. You can wear your own belt or we can provide one for you.

How much time will it take to fit 24hr BP?

It will take 15 minutes to fit with a 24hr blood pressure monitor but expect to be at London Heart Centre for 30 minutes.

What happens during the fitting of 24hr BP?

The first step is to record your blood pressure manually in both arms and then we’ll attach the blood pressure monitor and cuff to your upper arm. The cuff will usually be attached to your least dominant arm, for example to your left arm if you are right handed. The arm cuff connects via a small tube to the monitoring device, which is a small box worn on a belt around your waist. The blood pressure cuff will be inflated during your appointment to check the device is recording correctly. During your appointment we’ll ask you what time you get up and go to bed each day. We’ll then set-up the monitor to automatically record your blood pressure every 30 minutes during the day and every 60 minutes throughout the night.

What do I need to do?  

To allow the machine to work properly, it is important to make sure that the tube to the machine is not twisted or bent. Also, just before the machine is about to take a reading, it will alert you. When this happens you should

• sit down, if possible
• keep the cuff at the same level as your heart
• keep your arm still
• do not talk or cross your legs during the recording

It is recommended that you do not drive for the duration of your monitoring.

Do I need to do anything different because I’m being tested?

No. Because the test is being carried out to find out what your normal daily blood pressure is, it is important to carry on with your normal routine and do all the things you would normally do. You won’t be able to have a bath or a shower whilst you’re wearing the monitor as it must stay dry.

Will I need to keep a diary whilst having the monitoring done?

When we analyse the results, we rely on the information you provide in your diary. Sometimes there may be perfectly good reasons as to why your blood pressure was high, for example, when doing a brisk walk. Each time your blood pressure is recorded, you may be asked to make a note of the time and your activity (walking, sitting, etc.). You do not need to do this at night, but you must remember to complete the section on the diary which records when you went to sleep and woke up.

What are the risks from the test?

There are no known risks from the 24hr BP monitor test.

What happens after the test?

The 24hr BP recordings will be submitted to our Cardiologist who is a specially-trained physician in reading these recordings. They will interpret the recordings and will then provide your physician with a written report.

This information is based on

Patient information leaflet. British Hypertension Society.