What defines a ventricular escape rhythm?

What defines a ventricular escape rhythm?

• A. Complete block in the atrioventricular node
• B. Ventricular automaticity foci take over as the dominant pacemaker
• C. SA node pacing resumes spontaneously
• D. Presence of a junctional rhythm

Answer: (B)

A ventricular escape rhythm occurs when there is a failure of the higher pacemakers in the heart, commonly due to a complete block in atrioventricular (AV) conduction. This situation leads to the activation of ventricular automaticity foci, which can pace the heart at a slower rate. The presence of these automaticity foci in the ventricles provides a necessary backup mechanism to maintain heart rhythm when the primary pacemaker, typically the sinus node or AV node, is unable to function effectively.

In this scenario, the ventricular automaticity foci take over as the dominant pacemaker when there is significant block or failure of electrical signals from the atria or AV node to reach the ventricles. This results in an escape rhythm that usually has a rate that is slower than normal sinus rhythm but is sufficient to generate basic cardiac output.

The other options describe different cardiac phenomena that do not accurately capture what defines a ventricular escape rhythm. While the complete block in the AV node is a contributing factor, it does not define the escape rhythm itself, which is primarily tied to the autonomous activity in the ventricles. Similarly, the resumption of SA node pacing or the presence of a junctional rhythm represents alternative rhythm mechanisms that do not specifically denote a ventricular escape