ecgs

• How does an ECG work?

  • Electrodes that are capable of detecting electric signals are placed on the skin
  • These electrodes produce an electrocardiogram (ECG)
  • An ECG shows a number of distinctive electrical waves produced by the activity of the heart
• What is the P wave?

  • Caused by the depolarisation of the atria, which results in atrial contraction (systole)
• What is the QRS complex?

  caused by depolarisation of the ventricles, which results in ventricular contraction (systole)

  • This is the largest wave because the ventricles have the largest muscle mass
• What is the T wave?

  • Caused by the repolarisation of the ventricles, which results in ventricular relaxation (diastole)
• What is the U wave?

  • Scientists are still uncertain of the cause of the U wave, some think it is caused by the repolarisation of the Purkyne fibres
• Give a use of ECGs?

  to diagnose heart problems

  If someone has a suspected heart problem a doctor will often use an ECG as a diagnostic tool

  Some heart problems produce certain shapes or waves in an ECG which allow for a diagnosis
• What is tachycardia?

  • When the heart beats too fast it is tachycardic
  • An individual with a resting heart rate of over 100 bpm is said to have tachycardia
• What is bradycardia?


  When the heart beats too slow it is bradycardic

  • An individual with a resting heart rate below 60 bpm is said to have bradycardia
  • A lot of fit individuals or athletes tend to have lower heart rates and it is usually not dangerous
• What is an ectopic heartbeat?

  • This condition is caused by an early heartbeat followed by a pause/ an 'extra' heartbeat
  • It is common in the population and usually requires no treatment unless very severe
  • it can be caused by early contraction of the atria or ventricles
• What is fibrillation?

  • an irregular heartbeat will disrupt the rhythm of the heart
  • severe cases of fibrillation can be very dangerous, even fatal
  • the atria or ventricles completely lose their rhythm and stop contracting properly
  • it can result in anything from chest pain and fainting to lack of pulse and deat