Which arrhythmia is typically represented on an EKG strip as first degree heart block?

First degree heart block is characterized by a prolongation of the PR interval on an electrocardiogram (EKG) strip. Specifically, the PR interval exceeds 200 milliseconds, indicating a delay in the conduction of electrical impulses from the atria to the ventricles through the AV node. This results in a regular rhythm where each atrial depolarization (P wave) is followed by a ventricular depolarization (QRS complex), albeit after a longer-than-normal interval. This consistent pattern differentiates first degree heart block from other arrhythmias.

In contrast, normal sinus rhythm does not exhibit any conduction delay; it presents with a normal PR interval. Atrial fibrillation shows an irregularly irregular rhythm with absent discernible P waves, representing chaotic atrial activity rather than the delayed conduction of impulses. Ventricular fibrillation, a life-threatening condition, appears as rapid, erratic electrical activity with no defined waves, indicating complete loss of effective heartbeats.

Thus, the EKG representation of first degree heart block specifically demonstrates the prolonged PR interval, making it the correct answer in this context.