Question

A junctional escape beat occurs​ when:

A.The rate of the SA node is slower than that of the AV node


B.There is a conduction block between the SA node and AV node

C.The AV junction becomes irritable and temporarily overrides the SA node

D.There is an accessory pathway that causes reentry of the impulse at the AV node

Answer 1

A junctional escape beat occurs when there is a conduction block between the SA node and AV node, allowing the AV node to take over as the pacemaker, typically associated with a third-degree or complete AV block.

Step-by-step explanation:

A junctional escape beat occurs when there is a conduction block between the SA node and AV node. Essentially, it happens when the SA node, which normally sets the rhythm of the heart, fails to send an impulse or the impulse is not conducted. This leads to a pause that allows the AV node to take over as the pacemaker. While the SA node normally initiates impulses at 80-100 beats per minute, in the absence of the SA node, the AV node would create a heart rate of 40-60 beats per minute. The AV node has a slower inherent firing rate and will assume the role of pacemaker during an SA node malfunction, as seen in a third-degree or complete AV block.