What would a ventricular focus third degree AV block look like on an EKG?

What would a ventricular focus third degree AV block look like on an EKG?

• A. Some independent P waves and normal complexes
• B. Regular P waves with regular QRS complexes
• C. Some independent P waves and PVC-like QRS complexes
• D. Only P waves without any QRS complexes

Answer: (C)

In the context of a third-degree AV block, also known as complete heart block, the electrical signals from the atria (represented by P waves) and the ventricles (represented by QRS complexes) are dissociated. This means that the atria and the ventricles are not communicating with each other at all, leading to an independent pacing of each.

In this scenario, the characteristic finding on the EKG is the presence of P waves that occur independently of QRS complexes. The ventricular focus, which assumes control in the absence of normal conduction, typically produces QRS complexes that are wide and resemble those of premature ventricular contractions (PVCs). Therefore, the appearance of some independent P waves along with PVC-like QRS complexes is indicative of the ventricular escape rhythm that arises when the atrial signals are blocked from reaching the ventricles.

In conclusion, the combination of independent P waves and atypical QRS complexes aligns with the expected findings of a third-degree AV block when there is a ventricular focus, making that option the correct representation of this condition on an EKG.