1|Page
"ELECTROCARDIOGRAPHY FOR
HEALTHCARE PROFESSIONALS | 260+
PRACTICE QUESTIONS WITH RATIONALES |
HIGH-YIELD | RATED A+"
# Table of Contents
| Section | Topic | Question Numbers |
|---------|-------|------------------|
| I | Cardiac Anatomy & Electrophysiology | 1-25 |
| II | ECG Leads & Axis | 26-45 |
| III | Normal ECG Waveforms & Intervals | 46-65 |
| IV | Sinus Rhythms | 66-80 |
| V | Atrial Rhythms | 81-100 |
| VI | Junctional Rhythms | 101-115 |
| VII | Ventricular Rhythms | 116-140 |
| VIII | Heart Blocks (AV Blocks) | 141-160 |
| IX | Bundle Branch Blocks & Hemiblocks | 161-175 |
| X | Ischemia, Injury & Infarction (MI) | 176-200 |
| XI | Electrolyte Imbalances & Drug Effects | 201-220 |
| XII | Pacemakers & Miscellaneous | 221-240 |
,2|Page
| XIII | Mixed Review & Case Scenarios | 241-260 |
---
# SECTION I: Cardiac Anatomy & Electrophysiology (Questions 1-25)
**1.** Which structure is the primary pacemaker of the heart?
- A) Atrioventricular (AV) node
- B) Bundle of His
- C) Sinoatrial (SA) node
- D) Purkinje fibers
**Answer: C**
**Rationale:** The SA node has the fastest intrinsic firing rate (60-100
bpm) and normally overrides other pacemakers.
**2.** The normal intrinsic firing rate of the AV node is:
- A) 20-40 bpm
- B) 40-60 bpm
- C) 60-100 bpm
- D) 100-140 bpm
,3|Page
**Answer: B**
**Rationale:** AV node intrinsic rate is 40-60 bpm (secondary
pacemaker). Purkinje fibers are 20-40 bpm (tertiary).
**3.** Which ion is primarily responsible for the rapid depolarization
(Phase 0) of ventricular myocytes?
- A) Calcium (Ca2+)
- B) Potassium (K+)
- C) Sodium (Na+)
- D) Chloride (Cl-)
**Answer: C**
**Rationale:** Fast Na+ channels open during Phase 0 in non-
pacemaker cells, causing rapid depolarization.
**4.** Which phase of the cardiac action potential corresponds to the
plateau (calcium influx)?
- A) Phase 0
- B) Phase 1
- C) Phase 2
- D) Phase 3
**Answer: C**
, 4|Page
**Rationale:** Phase 2 is the plateau phase due to L-type Ca2+
channels balancing K+ efflux.
**5.** The absolute refractory period corresponds to which ECG
finding?
- A) Beginning of QRS to peak of T wave
- B) End of T wave to next P wave
- C) P wave to QRS complex
- D) QRS complex to U wave
**Answer: A**
**Rationale:** The absolute refractory period spans from the start of
QRS to the peak of the T wave; no new impulse can depolarize the cell.
**6.** Which statement about the sympathetic nervous system's effect
on the heart is correct?
- A) Increases heart rate (positive chronotropy) and increases conduction
velocity
- B) Decreases heart rate and decreases contractility
- C) Only affects ventricular contractility
- D) Decreases AV nodal conduction
**Answer: A**
"ELECTROCARDIOGRAPHY FOR
HEALTHCARE PROFESSIONALS | 260+
PRACTICE QUESTIONS WITH RATIONALES |
HIGH-YIELD | RATED A+"
# Table of Contents
| Section | Topic | Question Numbers |
|---------|-------|------------------|
| I | Cardiac Anatomy & Electrophysiology | 1-25 |
| II | ECG Leads & Axis | 26-45 |
| III | Normal ECG Waveforms & Intervals | 46-65 |
| IV | Sinus Rhythms | 66-80 |
| V | Atrial Rhythms | 81-100 |
| VI | Junctional Rhythms | 101-115 |
| VII | Ventricular Rhythms | 116-140 |
| VIII | Heart Blocks (AV Blocks) | 141-160 |
| IX | Bundle Branch Blocks & Hemiblocks | 161-175 |
| X | Ischemia, Injury & Infarction (MI) | 176-200 |
| XI | Electrolyte Imbalances & Drug Effects | 201-220 |
| XII | Pacemakers & Miscellaneous | 221-240 |
,2|Page
| XIII | Mixed Review & Case Scenarios | 241-260 |
---
# SECTION I: Cardiac Anatomy & Electrophysiology (Questions 1-25)
**1.** Which structure is the primary pacemaker of the heart?
- A) Atrioventricular (AV) node
- B) Bundle of His
- C) Sinoatrial (SA) node
- D) Purkinje fibers
**Answer: C**
**Rationale:** The SA node has the fastest intrinsic firing rate (60-100
bpm) and normally overrides other pacemakers.
**2.** The normal intrinsic firing rate of the AV node is:
- A) 20-40 bpm
- B) 40-60 bpm
- C) 60-100 bpm
- D) 100-140 bpm
,3|Page
**Answer: B**
**Rationale:** AV node intrinsic rate is 40-60 bpm (secondary
pacemaker). Purkinje fibers are 20-40 bpm (tertiary).
**3.** Which ion is primarily responsible for the rapid depolarization
(Phase 0) of ventricular myocytes?
- A) Calcium (Ca2+)
- B) Potassium (K+)
- C) Sodium (Na+)
- D) Chloride (Cl-)
**Answer: C**
**Rationale:** Fast Na+ channels open during Phase 0 in non-
pacemaker cells, causing rapid depolarization.
**4.** Which phase of the cardiac action potential corresponds to the
plateau (calcium influx)?
- A) Phase 0
- B) Phase 1
- C) Phase 2
- D) Phase 3
**Answer: C**
, 4|Page
**Rationale:** Phase 2 is the plateau phase due to L-type Ca2+
channels balancing K+ efflux.
**5.** The absolute refractory period corresponds to which ECG
finding?
- A) Beginning of QRS to peak of T wave
- B) End of T wave to next P wave
- C) P wave to QRS complex
- D) QRS complex to U wave
**Answer: A**
**Rationale:** The absolute refractory period spans from the start of
QRS to the peak of the T wave; no new impulse can depolarize the cell.
**6.** Which statement about the sympathetic nervous system's effect
on the heart is correct?
- A) Increases heart rate (positive chronotropy) and increases conduction
velocity
- B) Decreases heart rate and decreases contractility
- C) Only affects ventricular contractility
- D) Decreases AV nodal conduction
**Answer: A**
