HOAG ECG PRACTICE EXAM – QUESTIONS AND
ANSWERS | 2026/2027 LATEST UPDATE
SECTION 1: ECG FUNDAMENTALS AND CARDIAC ELECTRICAL CONDUCTION
Questions 1–10
1. What does an electrocardiogram primarily record?
A) Mechanical contraction of the heart chambers
B) Blood pressure changes within the cardiac chambers
C) The electrical activity of the heart
D) Oxygen saturation of cardiac tissue
Correct Answer: The electrical activity of the heart
Rationale: An electrocardiogram records electrical potentials generated by cardiac
depolarization and repolarization. These signals are detected through electrodes placed on
the skin and displayed as waveforms. ECG interpretation can provide information about
rhythm, conduction, ischemic changes, and other abnormalities. It does not directly measure
mechanical contraction or intracardiac pressure.
2. Which structure normally functions as the primary pacemaker of the heart?
A) Sinoatrial node
B) Atrioventricular node
C) Bundle of His
D) Purkinje fibers
Correct Answer: Sinoatrial node
Rationale: The sinoatrial node normally initiates the electrical impulse that produces each
heartbeat. The impulse then travels through the atria toward the AV node and the
ventricular conduction system. Because the SA node normally has the fastest intrinsic
pacemaker rate, it generally controls the heart's rhythm under normal conditions.
3. After leaving the sinoatrial node, which structure normally receives the impulse next?
A) Purkinje fibers
B) Atrioventricular node
C) Left bundle branch
D) Ventricular myocardium
,Correct Answer: Atrioventricular node
Rationale: The normal conduction sequence proceeds from the SA node through the atrial
myocardium to the AV node. The AV node provides an important delay that permits
ventricular filling before ventricular depolarization. The impulse then continues through the
His-Purkinje system to activate the ventricles.
4. Which sequence correctly describes normal ventricular conduction after the AV node?
A) Purkinje fibers → bundle of His → bundle branches
B) Bundle branches → AV node → Purkinje fibers
C) SA node → Purkinje fibers → AV node
D) Bundle of His → right and left bundle branches → Purkinje fibers
Correct Answer: Bundle of His → right and left bundle branches → Purkinje fibers
Rationale: After passing through the AV node, the impulse enters the bundle of His. It then
travels through the right and left bundle branches before spreading through the Purkinje
network. This organized pathway allows rapid and coordinated ventricular depolarization.
5. Which ECG waveform represents atrial depolarization?
A) P wave
B) QRS complex
C) T wave
D) U wave
Correct Answer: P wave
Rationale: The P wave represents atrial depolarization, which precedes atrial contraction. It
normally occurs before the QRS complex when atrial impulses are conducted through the AV
node. Changes in P-wave morphology can provide information about atrial enlargement or
abnormal atrial rhythm origins.
6. The QRS complex primarily represents which electrical event?
A) Atrial repolarization
B) Ventricular depolarization
C) Ventricular repolarization
D) SA-node firing
Correct Answer: Ventricular depolarization
Rationale: The QRS complex represents activation of the ventricles. Atrial repolarization
occurs at approximately the same time and is normally hidden within the QRS complex. The
,duration and morphology of the QRS can help identify ventricular conduction abnormalities,
bundle-branch blocks, and ventricular rhythms.
7. Which waveform normally represents ventricular repolarization?
A) P wave
B) Q wave
C) T wave
D) R wave
Correct Answer: T wave
Rationale: The T wave reflects ventricular repolarization following ventricular depolarization.
Its morphology and direction should be interpreted in the context of the ECG lead and clinical
situation. Abnormal T waves may occur with ischemia, electrolyte disturbances, ventricular
hypertrophy, medications, and conduction abnormalities.
8. What does the PR interval measure?
A) Ventricular depolarization through repolarization
B) Ventricular repolarization only
C) Atrial repolarization only
D) The interval from the beginning of atrial depolarization to the beginning of ventricular
depolarization
Correct Answer: The interval from the beginning of atrial depolarization to the beginning
of ventricular depolarization
Rationale: The PR interval begins with the onset of the P wave and ends with the beginning
of the QRS complex. It reflects conduction from the atria through the AV junction and into the
ventricles. A prolonged PR interval is characteristic of first-degree AV block.
9. Which statement best describes the QT interval?
A) It represents ventricular depolarization and repolarization
B) It represents only atrial depolarization
C) It measures only AV-node conduction
D) It measures the time between two consecutive P waves
Correct Answer: It represents ventricular depolarization and repolarization
Rationale: The QT interval extends from the beginning of ventricular depolarization to the
end of ventricular repolarization. Because QT duration varies with heart rate, corrected QT
, measurements are often used clinically. Excessive QT prolongation can increase susceptibility
to dangerous ventricular dysrhythmias.
10. Which statement correctly distinguishes a lead from an electrode?
A) An electrode is an electrical view and a lead is the adhesive pad
B) A lead and electrode are always identical terms
C) An electrode is placed on the skin, while a lead represents an electrical view derived from
electrode signals
D) A lead is only used for telemetry monitoring
Correct Answer: An electrode is placed on the skin, while a lead represents an electrical
view derived from electrode signals
Rationale: Electrodes are conductive sensors attached to the patient's skin. Leads represent
different electrical perspectives of cardiac activity based on the electrode configuration.
Understanding this distinction is important when obtaining and interpreting a standard 12-
lead ECG.
SECTION 2: LEAD PLACEMENT, ECG CALIBRATION, AND MEASUREMENTS
Questions 11–20
11. Which group contains the six standard precordial leads?
A) I, II, III, aVR, aVL, aVF
B) I, II, III, V1, V2, V3
C) V1, V2, V3, V4, V5, V6
D) aVR, aVL, aVF, V4, V5, V6
Correct Answer: V1, V2, V3, V4, V5, V6
Rationale: The six precordial or chest leads are V1 through V6. They provide horizontal-plane
views of cardiac electrical activity. The limb and augmented limb leads provide frontal-plane
perspectives, allowing the standard ECG to provide multiple views of the heart.
12. Which leads are classified as augmented limb leads?
A) I, II, III
B) aVR, aVL, aVF
C) V1, V2, V3
D) V4, V5, V6
Correct Answer: aVR, aVL, aVF
ANSWERS | 2026/2027 LATEST UPDATE
SECTION 1: ECG FUNDAMENTALS AND CARDIAC ELECTRICAL CONDUCTION
Questions 1–10
1. What does an electrocardiogram primarily record?
A) Mechanical contraction of the heart chambers
B) Blood pressure changes within the cardiac chambers
C) The electrical activity of the heart
D) Oxygen saturation of cardiac tissue
Correct Answer: The electrical activity of the heart
Rationale: An electrocardiogram records electrical potentials generated by cardiac
depolarization and repolarization. These signals are detected through electrodes placed on
the skin and displayed as waveforms. ECG interpretation can provide information about
rhythm, conduction, ischemic changes, and other abnormalities. It does not directly measure
mechanical contraction or intracardiac pressure.
2. Which structure normally functions as the primary pacemaker of the heart?
A) Sinoatrial node
B) Atrioventricular node
C) Bundle of His
D) Purkinje fibers
Correct Answer: Sinoatrial node
Rationale: The sinoatrial node normally initiates the electrical impulse that produces each
heartbeat. The impulse then travels through the atria toward the AV node and the
ventricular conduction system. Because the SA node normally has the fastest intrinsic
pacemaker rate, it generally controls the heart's rhythm under normal conditions.
3. After leaving the sinoatrial node, which structure normally receives the impulse next?
A) Purkinje fibers
B) Atrioventricular node
C) Left bundle branch
D) Ventricular myocardium
,Correct Answer: Atrioventricular node
Rationale: The normal conduction sequence proceeds from the SA node through the atrial
myocardium to the AV node. The AV node provides an important delay that permits
ventricular filling before ventricular depolarization. The impulse then continues through the
His-Purkinje system to activate the ventricles.
4. Which sequence correctly describes normal ventricular conduction after the AV node?
A) Purkinje fibers → bundle of His → bundle branches
B) Bundle branches → AV node → Purkinje fibers
C) SA node → Purkinje fibers → AV node
D) Bundle of His → right and left bundle branches → Purkinje fibers
Correct Answer: Bundle of His → right and left bundle branches → Purkinje fibers
Rationale: After passing through the AV node, the impulse enters the bundle of His. It then
travels through the right and left bundle branches before spreading through the Purkinje
network. This organized pathway allows rapid and coordinated ventricular depolarization.
5. Which ECG waveform represents atrial depolarization?
A) P wave
B) QRS complex
C) T wave
D) U wave
Correct Answer: P wave
Rationale: The P wave represents atrial depolarization, which precedes atrial contraction. It
normally occurs before the QRS complex when atrial impulses are conducted through the AV
node. Changes in P-wave morphology can provide information about atrial enlargement or
abnormal atrial rhythm origins.
6. The QRS complex primarily represents which electrical event?
A) Atrial repolarization
B) Ventricular depolarization
C) Ventricular repolarization
D) SA-node firing
Correct Answer: Ventricular depolarization
Rationale: The QRS complex represents activation of the ventricles. Atrial repolarization
occurs at approximately the same time and is normally hidden within the QRS complex. The
,duration and morphology of the QRS can help identify ventricular conduction abnormalities,
bundle-branch blocks, and ventricular rhythms.
7. Which waveform normally represents ventricular repolarization?
A) P wave
B) Q wave
C) T wave
D) R wave
Correct Answer: T wave
Rationale: The T wave reflects ventricular repolarization following ventricular depolarization.
Its morphology and direction should be interpreted in the context of the ECG lead and clinical
situation. Abnormal T waves may occur with ischemia, electrolyte disturbances, ventricular
hypertrophy, medications, and conduction abnormalities.
8. What does the PR interval measure?
A) Ventricular depolarization through repolarization
B) Ventricular repolarization only
C) Atrial repolarization only
D) The interval from the beginning of atrial depolarization to the beginning of ventricular
depolarization
Correct Answer: The interval from the beginning of atrial depolarization to the beginning
of ventricular depolarization
Rationale: The PR interval begins with the onset of the P wave and ends with the beginning
of the QRS complex. It reflects conduction from the atria through the AV junction and into the
ventricles. A prolonged PR interval is characteristic of first-degree AV block.
9. Which statement best describes the QT interval?
A) It represents ventricular depolarization and repolarization
B) It represents only atrial depolarization
C) It measures only AV-node conduction
D) It measures the time between two consecutive P waves
Correct Answer: It represents ventricular depolarization and repolarization
Rationale: The QT interval extends from the beginning of ventricular depolarization to the
end of ventricular repolarization. Because QT duration varies with heart rate, corrected QT
, measurements are often used clinically. Excessive QT prolongation can increase susceptibility
to dangerous ventricular dysrhythmias.
10. Which statement correctly distinguishes a lead from an electrode?
A) An electrode is an electrical view and a lead is the adhesive pad
B) A lead and electrode are always identical terms
C) An electrode is placed on the skin, while a lead represents an electrical view derived from
electrode signals
D) A lead is only used for telemetry monitoring
Correct Answer: An electrode is placed on the skin, while a lead represents an electrical
view derived from electrode signals
Rationale: Electrodes are conductive sensors attached to the patient's skin. Leads represent
different electrical perspectives of cardiac activity based on the electrode configuration.
Understanding this distinction is important when obtaining and interpreting a standard 12-
lead ECG.
SECTION 2: LEAD PLACEMENT, ECG CALIBRATION, AND MEASUREMENTS
Questions 11–20
11. Which group contains the six standard precordial leads?
A) I, II, III, aVR, aVL, aVF
B) I, II, III, V1, V2, V3
C) V1, V2, V3, V4, V5, V6
D) aVR, aVL, aVF, V4, V5, V6
Correct Answer: V1, V2, V3, V4, V5, V6
Rationale: The six precordial or chest leads are V1 through V6. They provide horizontal-plane
views of cardiac electrical activity. The limb and augmented limb leads provide frontal-plane
perspectives, allowing the standard ECG to provide multiple views of the heart.
12. Which leads are classified as augmented limb leads?
A) I, II, III
B) aVR, aVL, aVF
C) V1, V2, V3
D) V4, V5, V6
Correct Answer: aVR, aVL, aVF
