Adult electrocardiogram (ECG)

What is it about ?

The heart is a muscle that contracts under the influence of small electrical stimuli. These stimuli are produced by nerve cells found in the wall of the right atrium of the heart. These stimuli then diffuse to the whole muscle of the heart (myocardium).

This electrical activity of the heart can be seen by doing an electrocardiogram (ECG). Electrodes are attached to the wrists, ankles and the left side of the chest. They are used to capture the electric current flowing in all parts of the heart, by ‘looking’ at it from different angles. This electric current is therefore visible and printed on paper: it is the electrocardiogram (ECG).

What information does the ECG provide to the doctor?

The ECG allows the doctor to assess the activity of the heart. In particular, he can see:

• if the heartbeat is regular or not ;
• if the heart does not beat too fast Where too slowly ;
• if the heart muscle is not too thick ;
• if the heart is not too big ;
• if the myocardium is well supplied with blood (and thus see if a person has or has had a heart attack).

The doctor examines the shape of the tracing that appears on the ECG. Each part of this trace reflects the activity of a part of the heart: the atria, the passage between the atria and the ventricles, the wall that separates the two ventricles and the walls of the ventricles. The doctor can thus suspect and / or diagnose a cardiac abnormality. The ECG can also be useful later, to monitor the progress of the condition and assess the effect of treatment.

How does the doctor interpret an ECG?

Modern ECG machines themselves provide an interpretation of the ECG trace. But the doctor will never base himself on this interpretation alone. He will always examine the ECG carefully, as the device may make misinterpretations. The final responsibility therefore rests with the doctor.

The doctor will take into account the patient’s complaints when interpreting the ECG. It will measure all the waves of the ECG and compare them to those of a normal ECG. If the complaints persist, the doctor may decide to repeat the exam, even if the first ECG was normal. It happens that one or the other change does not appear on the ECG until after a certain time.

Want to know more?

The heart, its electrical activity and the ECG tracing – Fédération française de cardiologie

Source

Foreign clinical practice guide ‘Interpretation of the ECG in adults’ (2000), updated on 01.03.2017 and adapted to the Belgian context on 18.10.2019 – ebpracticenet