The use and interpretation of ECG traces Flashcards
What do ECGs do?
Electrocardiograms record electrical/cardiac activity in the body
What electrical charges do ECGs detect?
depolarisation and repolarisation
What is depolarisation and repolarisation?
electrical changed caused by the contraction of muscles
How do ECGs detect electrical changes?
through electrodes attached to the surface of the body
How is an electrocardiogram produced?
electrical changes associated with cardiac muscle contraction are inscribed on ruled strip of paper
What is the P wave?
-result of depolarisation, spreading across the atria from the SA node
-coincides with atrial systole
What is the QRS complex?
-result of depolarisation of ventricles
-coincides with ventricular systole
-atrial diastole
What is the T wave?
-result of repolarisation of ventricles, as ventricles begin to relax
-ventricular diastole
What condition do weak, uneven heartbeats with no period of diastole point towards?
ventricular fibrillation
Why might ventricular fibrillation cause weak, uneven heartbeats with no period of diastole?
-valve is not fully open so ventricle can’t fill up properly
-SAN is not functioning properly
-ventricle is spasming
-could lead to heart attack
What condition may a sudden dip in one of the heart beats point to?
Ectopic heartbeat
Why might ectopic heartbeat cause this to show on an electrocardiogram?
the heart has skipped a beat
What condition does a slow heart rate point towards?
bradycardia
What condition does a fast and elevated heart rate signify?
tachycardia/heart palpitations
