Electrocardiogram (ECG or EKG) is a medical test that measures and records the electrical activity of the heart.

The heart is a muscular organ that beats rhythmically to pump blood throughout the body, delivering oxygen to organs and tissues.

The sinoatrial node, SA node, is the natural pacemaker of the heart. It sends signals to the muscle fibres of the heart telling them when to contract. Each contraction is one heartbeat.

In an EKG test, the electrical impulses made while the heart is beating are recorded and documented on a strip of paper.

An electrocardiogram (ECG or EKG) is done to:

  • Assess the heart’s electrical activity for any abnormalities.
  • Find the cause of unexplained chest pain, such as from a heart attack, inflammation of the sac surrounding the heart (pericarditis), or angina.
  • Assess the cause of symptoms of heart disease, such as shortness of breath, dizziness, fainting, or rapid, irregular heartbeats (palpitations).
  • Find out if the walls of the heart chambers are too thick (hypertrophied).
  • Assess the health of the heart when other diseases or conditions are present, such as high blood pressure, high cholesterol, cigarette smoking, diabetes, or a family history of early heart disease.

During an EKG, the patient will lie on their back on a bed or table. Small metal discs called electrodes will be taped to the arms and legs to record the heart rate during the test.

A special EKG gel or small pads soaked in alcohol may be placed between the electrodes and your skin to improve conduction of the electrical impulses.

The electrodes may be moved at different times during the test to measure the heart’s electrical activity from different locations on the chest.