ECG Flashcards
To understand, perform and interpret ECGs
What causes a downward deflection?
Movement of the electricity away from the electrode
What causes an upwards deflection?
Movement of the electricity towards the electrode
What is the heart doing during the P wave?
Depolarisation spreading through the atria (atrial contraction)
What happens in the heart between the P wave and QRS complex?
The impulse passes through the AV node
What is the heart doing in the QRS complex?
Ventricle depolarisation/contraction, and atrial repolarisation
What is the heart doing in the T wave?
Repolarisation of ventricles
What is PEA?
Pulseless electrical activity - the appearance of normal-looking complexes on the ECG that should produce a pulse, but do not.
Can suggest PE, tamponade, tension pneumothorax, body salt disturbance, haemorrhage, lack of o2 due to hypothermia.
Why is it called a 12-lead ECG?
There are 10 physical leads - 4 limb leads, 6 chest leads. one of which is earth, and the other 9 create a plane from their interaction through which 3 more leads can be ‘created’.
What should the settings of the ECG machine be?
Paper speed: 25mm/s, 10mm/mV
Filter:150Hz
Where do you place the 4 limb leads?
Anterior forearms and medial mid-tibia. R = Right arm L = Left arm F = Left foot N = Right foot
Where do the chest leads go?
V1: 4ICS R V2: 4ICS L V4: 5ICS L Mid Cl V3: Between V2/4 V6: In line with V4 Mid Ax V5: Between V4/6
Why is a QRS complex both up and down?
The electrode is at an angle to the current, so first the current moves toward it, then away from it.
How long is each ‘small square’ and ‘big square’?
Small = 1mm = 0.04s Big = 5mm = 0.2s
Describe how the limb leads look at the heart.
aVR = RA from right arm aVL = laterally from left arm aVF = inferiorly I = laterally from a combination of aVL and aVF II = inferiorly from a combination of aVF and aVR III = inferiorly from a combination of aVF and aVL
Describe how the chest leads look at the heart.
ALL HORIZONTAL PLANE
V1/2 = Septum
V3/4 = anterior wall
V5/6 = lateral plane