Action Potential Graph
Left to Right
Downwards to the right
Downward to the left
Top to bottom
Towards the right arm
Towards the left arm
The sum of all the leads will be zero
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)
Marks atrial depolarization.
Marks ventricular depolarization
Marks ventricular repolarization.
Marks atrial depolarization and transmission through the AV node
Starts at the beginning of ventricular depolarization, includes ventricular contraction (mechanical not electrical), and to the end of ventricular repolarization.
The 5-step approach to analyzing ECGs.
4. PR interval
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:
2. Irregular with a pattern
3. Irregular with no pattern
4. Regular with miss or extra
P-Waves on ECGs
1. Are P-waves present?
2. Are they the same shape and size?
3. Are there more or fewer P-waves than QRS complexes?
4. Do the P-waves create QRS complexes?
PR Interval on ECGs
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