Question

In a complete A V node block,

A. no signals pass into the ventricles.
B. the atria will be paced by the SA node.
C. the ventricles contract due to the Purkinje fiber pacemaker.
D. All of the choices are correct.

Answer 1

In a complete AV node block, no signals pass into the ventricles, the atria are paced by the SA node, and the ventricles contract due to the Purkinje fiber pacemaker, meaning all provided options (A, B, C) are correct.

Step-by-step explanation:

The correct answer to the question: "In a complete AV node block, A. no signals pass into the ventricles. B. the atria will be paced by the SA node. C. the ventricles contract due to the Purkinje fiber pacemaker. D. All of the choices are correct," is D. All of the choices are correct. In a third-degree or complete AV node block, there is no electrical communication between the atria and the ventricles. Hence, the signal from the sinoatrial (SA) node cannot pass through the AV node to the ventricles (A). Despite this, the SA node still paces the atria (B). Meanwhile, in absence of the AV node's function, the Purkinje fibers initiate a separate, slower rhythm to cause the ventricles to contract, ensuring some level of cardiac output is maintained (C).