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Module title = Tutorial: Analyze the Waveforms
Lesson title = P waves! Where are you?
This is lesson 6 of 11 in this module
Identifying P waves is very important in determining where the electrical impulse within the heart is being generated.
Normal P waves that originate from the SA node move in an
anterior
(toward the front of the chest), and
downward
(toward the feet), and
leftward
direction. Therefore, ECG leads that measure electrical activity in these directions will show the P waves the best. As the wave of depolarization enters the left atrium, it is directed posteriorly a little bit and therefore, in lead V1 (which is good at meauring anterior-posterior), the P wave can be initially upgoing and then sometimes have a small downgoing portion at the end.
The 2 leads that show normal P waves the best are
lead II
(downward and to the left) and
V1
(anterior):
Lead II
V1
For this reason, a "rhythm strip" on a monitor that displays only one ECG lead will usually display lead II.
P waves can be different shapes and sizes, as shown below:
These P waves have 2 small peaks:
These P waves have a small bump:
These P waves are difficult to see. Maybe another lead would show them:
These P waves are upside down, which is called
inverted
:
In these examples, there are
no P waves
:
In this example, there is a lot of "garbage" in the baseline. There are no discrete well formed P waves.
The red arrow points to a
T wave
, not a P wave.
Now it is your turn to practice.
Lesson 6 of 11
That was the last lesson!
