Electrocardiogram (ECG) Test

An electrocardiogram (ECG) is a non-invasive test that measures the electrical activity of different parts of the heart muscle using superficial electrodes placed at twelve specific points (leads) on the chest and limbs (see figure 1).  The electrodes detect very small electrical signals from the heart during each heart beat (as the heart contracts and relaxes).  The heart’s electrical activities are recorded and displayed as line tracings seen as waves with spikes and dips on a moving strip of graph paper.  There are normal and abnormal patterns generated from each electrode that will help indicate the health of your heart.


This gives very important and useful information about the heart.  The ECG :

  • Can find the cause of an unexplained chest pain and can detect a heart attack or a significant blockage of your blood vessels supplying the heart muscle
  • Can reveal the causes of palpitations by recording the impulses that travels through the heart that determines the heart rate and rhythm and therefore show irregular patterns of the heartbeat, including life-threatening rhythm of the heart. An abnormal rhythm or heart rate is important because it directly affects the quality of blood flow to your vital organs.
  • Can detect predisposed conditions of family history of heart diseases, heart enlargement, electrolyte imbalances, metabolic diseases and even non-heart related diseases.

Interpretation of your ECG tracing require a very specialised skill.

Schematic representation of normal ECG

Figure 1: Placement of the precordial electrodes