ECG Flashcards
Lead 1
Positive = left wrist
Negative = right wrist
Angle = right shoulder to left shoulder
Lead 2
Positive = left angle
Negative = right wrist
Angle = right shoulder to left hip
Lead 3
Positive = left angle
Negative = left wrist
Angle = left shoulder to left angle
What is the order of the heart’s action potentials?
SA node
Atrium
AV node
Purkinje fibre
Ventricle
Which electrode is a viewpoint?
Positive
SA Node
Fires electrical signal to the AV node
Stimulates atria to contract
Doesn’t appear on an ECG
Slows down conduction of the action potential from atria to ventricles
Allows the ventricles to fully fill with blood before contraction
Atrial Depolarisation
Represented by the P wave
Causes a small upwards wave
Electrical signal moves through atria towards AV node
AV Node
Electrical signal reaches AV node with a delay to allow contracting atria to pump all the blood into the ventricles
Atria refills and SA node recharges
Electrical signal passes through to the bundle of His
Purkinje Fibres
Move electrical signal into the ventricles
This causes the ventricles to contract
As they contract the RV pumps blood to the lungs to oxygenate the blood and the LV pumps blood into the aorta
Ventricles are empty and atria are full
Process repeats
Bundle of His
Moves the electrical signal from the AV node to the Purkinje fibres