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Video: a CRT device implantation

Electrocardiography (ECG)

Electrocardiogram (ECG)
The ECG test is a totally safe test. It is undertaken in all patients in whom a cardiac problem is suspected and is also used in screening for heart disease. Small metal electrodes are stuck on the chest, legs and arms. They are then attached to wires that are connected to the ECG machine, which filters the signal and prints it. An ECG is an electrical map of the heart and provides information on whether the muscle has been damaged (myocardial infarction) and whether there is a disturbance of heart rhythm (arrhythmia). 

Ambulatory ECG
If you have an intermittent arrhythmia, this may not be detected by a standard ECG done at one particular time. You may then be advised to have an ambulatory ECG. This test records the electrical activity of your heart when you are walking about (ambulatory) and doing your normal activities. Wires from electrodes placed on your chest are connected to a small lightweight recorder. The recorder is attached to a belt which you wear round your waist. The electrical activity is usually recorded for 24-48 hours, sometimes longer.

You will be given a diary to record the times when you develop any symptoms (such as palpitations). The ECG tracing is analysed at the end of the test. But, any times you record where symptoms occurred will be most carefully analysed to see if there was an arrhythmia to account for the symptoms.

ECG event recorders

A variety of external ECG event recorders are available for recording rhythm abnormalities. They consist of devices that record the heart rhythm when they are activated.

Implantable loop recorders

An implantable loop recorder (ILR), or implantable cardiac monitor, is an implantable device that monitors the heart rhythm and heart rate automatically. The device, which is the size of a small matchbox, is implanted below the skin of the chest. The device is programmed to monitor the electrical activity of the heart continuously. The device is programmed to record abnormal heart rhythms. In addition, it records cardiac activity when you activate it with a remote control.  At the time when you have symptoms, you will need to place the remote control over the implanted device and press a button. This makes the device record the electrical activity of the heart before, during and after symptoms, such as loss of consciousness or palpitations. 

Exercise ECG

This consist of exercising you on a treadmill and assessing the ECG. Shortage of blood supply to the heart results in ECG changes. It is an indirect test for coronary heart disease. Combined with imaging, such as CT coronary angiography, it can be helpful in determining whether the shortage of blood supply is responsible for symptoms, such as chest pain. In addition, exercise testing can be useful in the assessment of cardiac rhythm disorders.


Exercise stress test

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