Page 1 of 334
HCA EKG INTERPRETATION EXAM
QUESTIONS
ORIGINAL CURRICULUM-ALIGNED
PRACTICE QUESTIONS — 2026–2027
## Table of Contents
1. Curriculum Coverage Blueprint
2. Section 1: Cardiac Anatomy & Electrophysiology (Questions 1–25)
3. Section 2: EKG Basics, Intervals & Measurements (Questions 26–50)
4. Section 3: Sinus Rhythms (Questions 51–75)
5. Section 4: Atrial Rhythms (Questions 76–95)
6. Section 5: Junctional Rhythms (Questions 96–110)
7. Section 6: Ventricular Rhythms (Questions 111–135)
8. Section 7: AV Blocks & Conduction Abnormalities (Questions 136–160)
9. Section 8: Pacemaker Rhythms (Questions 161–175)
10. Section 9: Ischemic & 12-Lead EKG Changes (Questions 176–190)
11. Section 10: Clinical Scenarios, Emergency Interventions & HCA Protocols (Questions 191–
210)
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## Section 1: Cardiac Anatomy & Electrophysiology
### Questions 1–25
**Question 1**
**Topic:** Cardiac Anatomy & Electrophysiology
**Learning objective:** Identify the location and function of the heart's primary pacemaker.
**Difficulty:** Easy
**Question:**
Which structure normally serves as the heart's primary pacemaker?
A. Atrioventricular (AV) node
B. Bundle of His
C. Purkinje fibers
D. Sinoatrial (SA) node
**Correct answer:** D — Sinoatrial (SA) node
**Detailed rationale:**
The SA node is the heart's natural pacemaker because it has the highest intrinsic firing rate
among all cardiac pacemaker cells, generating 60–100 impulses per minute under normal
resting conditions. The SA node is located in the upper wall of the right atrium near the opening
of the superior vena cava. Because it depolarizes most rapidly, it overrides the slower intrinsic
rates of other pacemaker tissues through a mechanism called overdrive suppression.
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**Why the other options are incorrect:**
- **A: AV node** — The AV node has an intrinsic rate of 40–60 bpm and serves primarily to
delay conduction between the atria and ventricles, not as the primary pacemaker.
- **B: Bundle of His** — The Bundle of His conducts impulses from the AV node to the bundle
branches but does not function as a primary pacemaker under normal conditions.
- **C: Purkinje fibers** — Purkinje fibers have an intrinsic rate of only 20–40 bpm and serve as
a backup pacemaker only when higher pacemakers fail.
**Exam tip:**
Remember the "60-40-20 rule" for intrinsic rates: SA node = 60–100 bpm, AV node = 40–60
bpm, Purkinje fibers = 20–40 bpm. The fastest pacemaker wins!
---
**Question 2**
**Topic:** Cardiac Anatomy & Electrophysiology
**Learning objective:** Recall the normal intrinsic firing rate of the SA node.
**Difficulty:** Easy
**Question:**
What is the normal intrinsic firing rate of the sinoatrial (SA) node in a resting adult?
A. 20–40 beats per minute
B. 40–60 beats per minute
C. 60–100 beats per minute
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D. 100–150 beats per minute
**Correct answer:** C — 60–100 beats per minute
**Detailed rationale:**
The SA node normally generates electrical impulses at a rate of 60–100 beats per minute in a
resting adult. This intrinsic automaticity is the result of spontaneous phase 4 depolarization in
SA nodal cells. Rates below 60 bpm indicate bradycardia; rates above 100 bpm indicate
tachycardia.
**Why the other options are incorrect:**
- **A: 20–40 bpm** — This is the intrinsic rate of the Purkinje fibers, the lowest-level backup
pacemaker.
- **B: 40–60 bpm** — This is the intrinsic rate of the AV node, the secondary pacemaker.
- **D: 100–150 bpm** — This exceeds normal SA node resting rate and would be considered
sinus tachycardia or an ectopic atrial tachycardia.
**Exam tip:**
The SA node is the "captain" of the heart's electrical system — it sets the pace. The AV node is
the "first officer" (40–60 bpm), and the Purkinje fibers are the "third officer" (20–40 bpm). Know
these three rates cold!
---
**Question 3**
**Topic:** Cardiac Anatomy & Electrophysiology
HCA EKG INTERPRETATION EXAM
QUESTIONS
ORIGINAL CURRICULUM-ALIGNED
PRACTICE QUESTIONS — 2026–2027
## Table of Contents
1. Curriculum Coverage Blueprint
2. Section 1: Cardiac Anatomy & Electrophysiology (Questions 1–25)
3. Section 2: EKG Basics, Intervals & Measurements (Questions 26–50)
4. Section 3: Sinus Rhythms (Questions 51–75)
5. Section 4: Atrial Rhythms (Questions 76–95)
6. Section 5: Junctional Rhythms (Questions 96–110)
7. Section 6: Ventricular Rhythms (Questions 111–135)
8. Section 7: AV Blocks & Conduction Abnormalities (Questions 136–160)
9. Section 8: Pacemaker Rhythms (Questions 161–175)
10. Section 9: Ischemic & 12-Lead EKG Changes (Questions 176–190)
11. Section 10: Clinical Scenarios, Emergency Interventions & HCA Protocols (Questions 191–
210)
,Page 2 of 334
## Section 1: Cardiac Anatomy & Electrophysiology
### Questions 1–25
**Question 1**
**Topic:** Cardiac Anatomy & Electrophysiology
**Learning objective:** Identify the location and function of the heart's primary pacemaker.
**Difficulty:** Easy
**Question:**
Which structure normally serves as the heart's primary pacemaker?
A. Atrioventricular (AV) node
B. Bundle of His
C. Purkinje fibers
D. Sinoatrial (SA) node
**Correct answer:** D — Sinoatrial (SA) node
**Detailed rationale:**
The SA node is the heart's natural pacemaker because it has the highest intrinsic firing rate
among all cardiac pacemaker cells, generating 60–100 impulses per minute under normal
resting conditions. The SA node is located in the upper wall of the right atrium near the opening
of the superior vena cava. Because it depolarizes most rapidly, it overrides the slower intrinsic
rates of other pacemaker tissues through a mechanism called overdrive suppression.
,Page 3 of 334
**Why the other options are incorrect:**
- **A: AV node** — The AV node has an intrinsic rate of 40–60 bpm and serves primarily to
delay conduction between the atria and ventricles, not as the primary pacemaker.
- **B: Bundle of His** — The Bundle of His conducts impulses from the AV node to the bundle
branches but does not function as a primary pacemaker under normal conditions.
- **C: Purkinje fibers** — Purkinje fibers have an intrinsic rate of only 20–40 bpm and serve as
a backup pacemaker only when higher pacemakers fail.
**Exam tip:**
Remember the "60-40-20 rule" for intrinsic rates: SA node = 60–100 bpm, AV node = 40–60
bpm, Purkinje fibers = 20–40 bpm. The fastest pacemaker wins!
---
**Question 2**
**Topic:** Cardiac Anatomy & Electrophysiology
**Learning objective:** Recall the normal intrinsic firing rate of the SA node.
**Difficulty:** Easy
**Question:**
What is the normal intrinsic firing rate of the sinoatrial (SA) node in a resting adult?
A. 20–40 beats per minute
B. 40–60 beats per minute
C. 60–100 beats per minute
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D. 100–150 beats per minute
**Correct answer:** C — 60–100 beats per minute
**Detailed rationale:**
The SA node normally generates electrical impulses at a rate of 60–100 beats per minute in a
resting adult. This intrinsic automaticity is the result of spontaneous phase 4 depolarization in
SA nodal cells. Rates below 60 bpm indicate bradycardia; rates above 100 bpm indicate
tachycardia.
**Why the other options are incorrect:**
- **A: 20–40 bpm** — This is the intrinsic rate of the Purkinje fibers, the lowest-level backup
pacemaker.
- **B: 40–60 bpm** — This is the intrinsic rate of the AV node, the secondary pacemaker.
- **D: 100–150 bpm** — This exceeds normal SA node resting rate and would be considered
sinus tachycardia or an ectopic atrial tachycardia.
**Exam tip:**
The SA node is the "captain" of the heart's electrical system — it sets the pace. The AV node is
the "first officer" (40–60 bpm), and the Purkinje fibers are the "third officer" (20–40 bpm). Know
these three rates cold!
---
**Question 3**
**Topic:** Cardiac Anatomy & Electrophysiology
