Now we are going to third-degree AV block.
What is happening here? No correlation, of
what? No correlation of the P waves to the
QRS complex and the reason for that? Well.
If your patient has suffered myocardial infarction,
gone is the heart. And if the heart is not
working properly and you cannot control, or should
I say SA node cannot control the rest of
the conduction system, the impulse is not
being originated from the SA node. The P wave
might be there, but is not continuing any
further through the AV node. So the complete
third-degree AV block. "But Dr. Raj, I see QRS
complexes, where is that coming from?" You know
the entire heart intrinsically is a pacemaker.
So once the SA node loses its control, the
QRS complex will still be present. The ventricle
is still going to originate or develop a QRS
complex. That is called a ectopic foci.
Therefore, the atria beats at their own rate.
The intrinsic ventricular rate is about 30
beats per minute. Patients are very symptomatic
as you can imagine. Treatment, placement
of a permanent pacemaker with third-degree
AV block. There's really no other ways to do
this and you need to make sure that you get
everything back in order. With third degree
AV block, you have noticed the bottom strip
once again, there is no correlation between
that P wave and that QRS complex. And when the
QRS complex do show up, well it is bizarre
looking. Where is that QRS complex coming
from? It is not the SA node that is in control.
It is the fact that you have an ectopic foci.