January 7, 2016 - Introduction to Electrocardiography Flashcards
Action Potential Graph
Lead 1
Left to Right
Lead 2
Downwards to the right
Lead 3
Downward to the left
Lead aVF
Top to bottom
Lead aVR
Towards the right arm
Lead aVL
Towards the left arm
Einthoven’s Triangle
The sum of all the leads will be zero
Precordial Leads
V1, V2, V3, V4, V5, and V6
Placed from near the sternum, around the heart, to under the left armpit.
Leads and “Planes”
The limb leads cannot measure front and back (they only measure coronal plane)
The precordial leads cannot measure head to toe (they only measure transverse plane)
P-wave
Marks atrial depolarization.
QRS Complex
Marks ventricular depolarization
T-wave
Marks ventricular repolarization.
PR Interval
Marks atrial depolarization and transmission through the AV node
QT Interval
Starts at the beginning of ventricular depolarization, includes ventricular contraction (mechanical not electrical), and to the end of ventricular repolarization.
Rate on ECG
Calculated by dividing 300 by the number of big squares between beats.
Normal is 60-100, bradycardia is <60, and tachycardia is >100.
Rhythm on ECGs
There are four types of rhythm:
- Regular
- Irregular with a pattern
- Irregular with no pattern
- Regular with miss or extra
P-Waves on ECGs
Ask yourself…
- Are P-waves present?
- Are they the same shape and size?
- Are there more or fewer P-waves than QRS complexes?
- Do the P-waves create QRS complexes?
PR Interval on ECGs
Ask yourself…
1. Is the PR interval short, normal, or long?
Short is defined as less than 3 little squares, normal is 3-5 little squares, and long is more than 5 little squares.
2. Does the PR interval change or is it constant?
QRS Complex on ECGs
Ask yourself if the width of the QRS complex is narrow (normal) or wide?
Normal QRS is less than 3 little squares
