Friday Facts

Nice schematic of where the P-QRS waves and their relevant impulses originate from on an EKG during a cardiac cycle:

1. Depolarization of the sinus node.
2. Conduction through atrial fibers.
3. Delayed conduction through the AV node and His.
4. Rapid conduction through the His Purkinje fibers and bundle branches to depolarize the ventricle.

If you can correlate what you are seeing on an EKG with what is actually happening within the heart, things will make a lot more sense to you!
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Ref: Ali Haider, MD: Lily, Pathophysiology of Heart Disease.