DC Dysrhythmia Pathophysiology & Electrophysiology

Question 1

What is the normal pacemaker of the heart and its intrinsic rate?

Accepted Answer

SA node, 60–100 bpm

Answer

The sinoatrial (SA) node is the dominant pacemaker with an intrinsic firing rate of 60–100 bpm, the fastest rate in the cardiac conduction hierarchy, so it drives the normal rhythm.

Question 2

What is the primary function of the AV node in cardiac conduction?

Accepted Answer

Delay impulse transmission to allow ventricular filling

Answer

The AV node delays the impulse by 0.12–0.20 seconds to allow atrial contraction to complete and ventricles to fill before ventricular systole begins, reflected as the PR interval on ECG.

Question 3

Which structure divides into the right and left bundle branches?

Accepted Answer

Bundle of His

Answer

The Bundle of His (common bundle) arises from the AV node and bifurcates into the right and left bundle branches at the superior interventricular septum.

Question 4

What is the intrinsic escape rate of AV junctional tissue if the SA node fails?

Accepted Answer

40–60 bpm

Answer

AV junctional tissue has an intrinsic rate of 40–60 bpm, serving as a secondary pacemaker that produces a junctional escape rhythm when the SA node fails to fire.

Question 5

In which direction does normal ventricular depolarization travel through the Purkinje network?

Accepted Answer

From endocardium to epicardium

Answer

Normal ventricular depolarization travels from endocardium (inner wall) to epicardium (outer wall) via the Purkinje fibers, producing a narrow, organized QRS complex.

(DC) Dysrhythmia Certification Practice Test

(DC) Dysrhythmia Certification Practice Test

DC Dysrhythmia Pathophysiology & Electrophysiology