EKG TECHNICIAN (NHA CET)
Exam Prep / Study Guide
Multiple-Choice Questions with Answers & Rationales
.
Section 1: Cardiac Anatomy, Physiology & Conduction
1. Which structure is the primary pacemaker of the heart?
A. AV node
B. SA node
C. Bundle of His
D. Purkinje fibers
Answer: B. SA node
Rationale: The sinoatrial (SA) node has the fastest intrinsic firing
rate (60–100 bpm), so it normally sets the heart rate and is the
primary pacemaker.
2. What is the normal intrinsic firing rate of the SA node?
A. 20–40 bpm
B. 40–60 bpm
C. 60–100 bpm
D. 100–150 bpm
Answer: C. 60–100 bpm
Rationale: The SA node fires at 60–100 impulses per minute. The
AV junction fires at 40–60 and the ventricles at 20–40.
EKG NHA Study Guide | Page 1
,3. What is the intrinsic rate of the AV junction when it acts as the
pacemaker?
A. 20–40 bpm
B. 40–60 bpm
C. 60–80 bpm
D. 80–100 bpm
Answer: B. 40–60 bpm
Rationale: The AV junction acts as a backup pacemaker at 40–60
bpm when the SA node fails to fire.
4. What is the intrinsic rate of the ventricles when they act as the
pacemaker?
A. 20–40 bpm
B. 40–60 bpm
C. 60–100 bpm
D. 100–120 bpm
Answer: A. 20–40 bpm
Rationale: Ventricular escape (idioventricular) rhythm is 20–40
bpm. It is the slowest and least reliable pacemaker site.
5. Which part of the conduction system delays the impulse so the
ventricles can fill before contracting?
A. SA node
B. Bundle branches
C. AV node
D. Purkinje fibers
Answer: C. AV node
Rationale: The AV node slows conduction, giving the atria time to
empty into the ventricles (atrial kick) before ventricular
contraction.
EKG NHA Study Guide | Page 2
,6. Which is the correct sequence of normal electrical conduction?
A. SA node → AV node → bundle of His → bundle branches →
Purkinje fibers
B. SA node → bundle of His → AV node → Purkinje fibers → bundle
branches
C. AV node → SA node → bundle branches → bundle of His →
Purkinje fibers
D. SA node → Purkinje fibers → AV node → bundle of His → bundle
branches
Answer: A. SA node → AV node → bundle of His → bundle
branches → Purkinje fibers
Rationale: The impulse starts in the SA node, crosses the atria,
slows at the AV node, then travels down the bundle of His, right
and left bundle branches, and out through the Purkinje fibers.
7. Which heart chamber has the thickest muscular wall?
A. Right atrium
B. Left atrium
C. Right ventricle
D. Left ventricle
Answer: D. Left ventricle
Rationale: The left ventricle pumps blood into the high-pressure
systemic circulation, so it has the thickest myocardium.
EKG NHA Study Guide | Page 3
, 8. On the EKG, atrial depolarization is represented by the:
A. QRS complex
B. P wave
C. T wave
D. U wave
Answer: B. P wave
Rationale: The P wave represents atrial depolarization (which
triggers atrial contraction).
9. On the EKG, ventricular repolarization is represented by the:
A. T wave
B. P wave
C. PR interval
D. QRS complex
Answer: A. T wave
Rationale: The T wave represents ventricular repolarization
(recovery). Atrial repolarization is hidden within the QRS complex.
10. Which valve lies between the left atrium and the left ventricle?
A. Tricuspid valve
B. Aortic valve
C. Mitral (bicuspid) valve
D. Pulmonic valve
Answer: C. Mitral (bicuspid) valve
Rationale: The mitral (bicuspid) valve separates the left atrium
from the left ventricle. The tricuspid valve is on the right side.
EKG NHA Study Guide | Page 4
Exam Prep / Study Guide
Multiple-Choice Questions with Answers & Rationales
.
Section 1: Cardiac Anatomy, Physiology & Conduction
1. Which structure is the primary pacemaker of the heart?
A. AV node
B. SA node
C. Bundle of His
D. Purkinje fibers
Answer: B. SA node
Rationale: The sinoatrial (SA) node has the fastest intrinsic firing
rate (60–100 bpm), so it normally sets the heart rate and is the
primary pacemaker.
2. What is the normal intrinsic firing rate of the SA node?
A. 20–40 bpm
B. 40–60 bpm
C. 60–100 bpm
D. 100–150 bpm
Answer: C. 60–100 bpm
Rationale: The SA node fires at 60–100 impulses per minute. The
AV junction fires at 40–60 and the ventricles at 20–40.
EKG NHA Study Guide | Page 1
,3. What is the intrinsic rate of the AV junction when it acts as the
pacemaker?
A. 20–40 bpm
B. 40–60 bpm
C. 60–80 bpm
D. 80–100 bpm
Answer: B. 40–60 bpm
Rationale: The AV junction acts as a backup pacemaker at 40–60
bpm when the SA node fails to fire.
4. What is the intrinsic rate of the ventricles when they act as the
pacemaker?
A. 20–40 bpm
B. 40–60 bpm
C. 60–100 bpm
D. 100–120 bpm
Answer: A. 20–40 bpm
Rationale: Ventricular escape (idioventricular) rhythm is 20–40
bpm. It is the slowest and least reliable pacemaker site.
5. Which part of the conduction system delays the impulse so the
ventricles can fill before contracting?
A. SA node
B. Bundle branches
C. AV node
D. Purkinje fibers
Answer: C. AV node
Rationale: The AV node slows conduction, giving the atria time to
empty into the ventricles (atrial kick) before ventricular
contraction.
EKG NHA Study Guide | Page 2
,6. Which is the correct sequence of normal electrical conduction?
A. SA node → AV node → bundle of His → bundle branches →
Purkinje fibers
B. SA node → bundle of His → AV node → Purkinje fibers → bundle
branches
C. AV node → SA node → bundle branches → bundle of His →
Purkinje fibers
D. SA node → Purkinje fibers → AV node → bundle of His → bundle
branches
Answer: A. SA node → AV node → bundle of His → bundle
branches → Purkinje fibers
Rationale: The impulse starts in the SA node, crosses the atria,
slows at the AV node, then travels down the bundle of His, right
and left bundle branches, and out through the Purkinje fibers.
7. Which heart chamber has the thickest muscular wall?
A. Right atrium
B. Left atrium
C. Right ventricle
D. Left ventricle
Answer: D. Left ventricle
Rationale: The left ventricle pumps blood into the high-pressure
systemic circulation, so it has the thickest myocardium.
EKG NHA Study Guide | Page 3
, 8. On the EKG, atrial depolarization is represented by the:
A. QRS complex
B. P wave
C. T wave
D. U wave
Answer: B. P wave
Rationale: The P wave represents atrial depolarization (which
triggers atrial contraction).
9. On the EKG, ventricular repolarization is represented by the:
A. T wave
B. P wave
C. PR interval
D. QRS complex
Answer: A. T wave
Rationale: The T wave represents ventricular repolarization
(recovery). Atrial repolarization is hidden within the QRS complex.
10. Which valve lies between the left atrium and the left ventricle?
A. Tricuspid valve
B. Aortic valve
C. Mitral (bicuspid) valve
D. Pulmonic valve
Answer: C. Mitral (bicuspid) valve
Rationale: The mitral (bicuspid) valve separates the left atrium
from the left ventricle. The tricuspid valve is on the right side.
EKG NHA Study Guide | Page 4
