electrocardiographs

• electrocardiogram measures the tiny electrical differences in your skin resulting from the electrical activity of the heart
• the heart muscle depolarises ( loses charge ) when it contracts and it repolarises ( gains charge ) when it contracts
• tachycardia - when the heartbeat is too quick

  
• ectopic heartbeat - extra heartbeats that are out of normal rhythm

  
• atrial fibrillation - abnormal rhythm of the heart. Rapid electrical impulses are generated in the atria and they contract very fast but don't retract properly