Home > Patients > Diagnosis > Heart monitoring

Heart Rhythm Monitoring


Approaching 100,000 people in the UK die each year as a result of a treatable but undetected heart rhythm disorder.  This highlights the vital importance of effective diagnosis.  Even routine manual pulse checks can detect many arrhythmias for diagnostic testing.


Monitoring of the heart’s rhythm is the cornerstone of the diagnosis of cardiac arrhythmias.  This is achieved in various ways, and also under different conditions where a clinician will attempt to replicate symptoms, reveal a hidden arrhythmia and correlate arrhythmias with specific events. In heart rhythm testing, the electrical activity of your heart is recorded to identify problems. Common heart monitoring techniques include:

  • Electrocardiogram (ECG or EKG)
  • Holter monitor (24h monitoring for days at a time)
  • Implantable loop recorders (months of continuous monitoring)

In recent years, new technologies have also been developed to support patients who wish to monitor their heart rhythm and share results with their doctor. You can learn more about these devices by visiting our Lifesaving and heart rhythm devices page here.

Over the years, the ECG has been developed to become one of the most important tests in the investigation of heart-related problems. It can help a doctor understand the possible role of the heart in a person’s symptoms or problem.


If you are suffering with unexplained blackouts or a related condition, then your specialist or doctor may ask for this test. Every patient presenting with blackouts should undergo an ECG. A resting ECG is an important test as it may help to rule out many underlying heart conditions.


The test is painless and harmless, recording electrical impulses that come from your heart. At no point does this put electricity into your body, or cause any side effects.


An ECG test takes about five minutes. Electrodes (small sticky pads) are attached to your arms, legs and chest and the wires lead to the ECG machine. The machine can then read what is happening to your heart and record the information onto paper.


Through the different electrodes, the ECG gives 12 different electrical pictures of the heart. For this reason it is often also called a ‘12 lead ECG’. The ECG will tell the specialist whether your heart rate is too fast, too slow or irregular.


It is common to have more than one ECG recorded while being investigated for blackouts. This gives individual clinicians a chance to review a fresh test to give their own opinion on the heart trace. This can also help if the trace changes over time.

If your symptoms ‘come and go’ your doctor might suggest a Holter Monitor test, which is a continuous ECG recoding over approximately 24 hours. Again, electrodes will be placed on your body, and this time they will be taped down. During a Holter Monitor test the wires will be attached to a smaller, portable device which can be strapped to the chest. After the specified time period the monitor can be returned to your doctor to see whether any arrhythmias have been indicated.

If the cause of your symptoms can not be determined following an ECG and a Holter Monitor test, then your doctor may consider an Implantable Loop Recorder (ILR). The ILR can monitor heart rhythms for months at a time, and can remain in place for up to three year. An ILR has to be inserted underneath your skin, just below the collarbone. In order to record an episode you must press a button on a hand held activator while it is placed over the ILR. This must be done either whilst experiencing symptoms or as near to the event as possible.