ECG - Normal ECG Flashcards
What does the P-wave correspond to?
Atrial depolarisation
What does the QRS complex correspond to?
Ventricular depolarisation
What does the T-wave correspond to?
Ventricular repolarisation
What does positive deflection indicate on an ECG wave?
Depolarisation moving towards the positive electrode causes a positive, or upwards, deflection on the ECG.
What does a negative deflection on an ECG wave indicate in terms of direction of electrical flow?
- Depolarisation moving away from the positive electrode
- Repolarisation towards a positive electrode
Draw the vectors of leads I, II and III, aVR, aVF and aVL
I = L Arm to R Arm
II = R Arm to L leg
III = L Arm to L Leg
What are the positions of V1 to V6 chest leads?
- V1 - 4th intercostal space, right parasternal edge
- V2 - 4th intercostal space, left parasternal edge
- V3 - between V2 and V4
- V4 - 5th intercostal space, midclavicular line
- V5 - 5th intercostal space, anterior axillary line
- V6 - 5th intercostal space, midaxillary line
Which leads look at the left lateral surface?
I and aVL, V5 and V6
Which leads look at the inferior surface?
II, III and aVF
Which leads look at the right atrium?
aVR
Which leads look at the IV septum?
V1 + V2
Which leads look at the anterior walls of the left ventricle?
V3 and V4
What should the ECG running speed be set to?
25 mm/s
How many seconds are in a large square?
0.2 seconds
How many seconds are in a small square?
0.04 seconds
How long should the PR interval be?
0.12 - 0.2 s (3-5 small squares)
How long should a QRS complex be?
<0.12 s (<3 small boxes)
How long should the QT interval last in men at 60 BPM?
< 0.45 s
What determines the magnitude of deflection (either up or down) on an ECG recording?
The magnitude of the deflection is determined by how parallel the electrical force is to the axis of the lead being examined. The more parallel, the greater the magnitude of deflection
If the electrical force was directed perpendicular to an ECG lead, what would be recorded?
The lead would not register any activity