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Cardiac Conduction/EKG Interpretation

Human Anatomy, Physiology, and Medicine. Anything human!

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Cardiac Conduction/EKG Interpretation

Postby Jedi of Zen » Wed Jun 13, 2007 6:16 pm

As cardiac nerve transmission flows through the pathway of SA Node, atrial syncytium, junctional fibers, AV Node, Bundle of His, Purkinje fibers, and finally, ventricular syncytium - at what point along this pathway does ventricular depolarization actually begin?

My answer is that it does not begin until after it has reached the ventricular syncytium. To me, this is a significant point, because looking at textbook pictures of the cardiac nerve pathways can lead one to believe that once the nerve transmission has surpassed the AV node and reaches the Bundle of His - boom, you're in the ventricles now. But as I see it, this is not the case. At the Bundle of His, you are still in the Interventricular septum - not the actual ventricles themselves. It's not until after the nerve transmission surpasses the Purkinje fibers that you have reached the actual ventricles.

I work as a Cardiology Tech at a hospital. My primary job duty is to perform 12-lead EKGs. My training materials indicate that in an EKG tracing, nerve transmission has already reached the Purkinje fibers prior to the onset of the Q wave. However, it also says that ventricular depolarization does not begin until said onset of Q wave (ie, ventricular depolarization lasts throughout the entire QRS complex).

So my question about all of this is, again - where along the nerve pathway does ventricular depolarization begin? I used to assume that it began upon reaching the AV Node/Bundle of His area, just from looking at illustrations of the heart. But now I'm starting to suspect that it actually doesn't start until it has surpassed the Purkinjes and reaches the ventricular syncytium. Am I correct on that?

Thank you for your time,

the Jedi.
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Postby Jedi of Zen » Mon Jun 18, 2007 1:46 am

No takers?

No doctors or cardiologists out there?

:(
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