ECG

• Electrocardiograms


  Electrical activity that spreads through the heart during the cardiac cycle can be detected using electrodes placed on the skin
• Electrocardiogram procedure


  1. Electrical signals can then be shown on a cathode ray oscilloscope

  2. Electrical signals can then be shown on a chart read recorder
• Electrocardiogram


  The record produced by the electrocardiogram procedure
• Typical ECG


  • Consists of characteristic patterns, or waves, which correspond to particular events in the cardiac cycle
• P wave


  • Shows the depolarisation of the atria during atrial systole
• QRS wave


  • Shows the spread of depolarisation through the ventricles resulting in ventricular systole
• T wave


  • Shows the repolarisation of the ventricles during ventricular diastole
• Diagnosing heart conditions


  1. Patterns are studied in different conditions and compared to the standard ECG

  2. To diagnose heart conditions, such as arrhythmias (abnormal rhythm) and fibrillation
• Stopping fibrillation


  1. Passing a strong electric current through the chest wall

  2. The heart stops for up to 5 seconds after which it begins to beat in a controlled way