SHARP EKG (ECG Interpretation, Cardiology
& Nursing) Study Guide 2026/2027 | High-
Yield ECG Practice Questions, Rhythm
Interpretation & Detailed Rationales
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SHARP EKG (ECG INTERPRETATION, CARDIOLOGY & NURSING)
STUDY GUIDE 2026/2027
High-Yield ECG Practice Questions, Rhythm Interpretation
& Detailed EXPERT RATIONALE
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
OVERVIEW
• This guide delivers 200 high-yield, exam-ready ECG and cardiology nursing
questions with five options each, a clearly marked correct answer, and a clinically
grounded EXPERT RATIONALE — designed to sharpen your rhythm recognition
and critical thinking under real exam pressure.
• Study this material by reading the EXPERT RATIONALE for every question — right
or wrong — to reinforce the "why" behind each answer, building the pattern
recognition and nursing judgment that top scores and safe clinical practice both
demand.
Q1. What is the normal duration of a PR interval on a standard ECG?
A. 0.06 – 0.10 seconds
B. 0.12 – 0.20 seconds
C. 0.22 – 0.30 seconds
D. 0.30 – 0.40 seconds
,E. 0.40 – 0.50 seconds
Correct Answer: B. 0.12 – 0.20 seconds
EXPERT RATIONALE: The PR interval reflects conduction time from the SA node
through the atria and AV node to the ventricles. A normal PR interval is 0.12–0.20
seconds (3–5 small boxes on ECG paper). Values above 0.20 seconds indicate a first-
degree AV block.
Q2. What does the QRS complex represent on the ECG?
A. Atrial repolarization
B. Ventricular repolarization
C. Ventricular depolarization
D. Atrial depolarization
E. SA node firing
Correct Answer: C. Ventricular depolarization
EXPERT RATIONALE: The QRS complex represents the electrical depolarization
of the ventricles, which triggers ventricular contraction. Normal QRS duration is
0.06–0.10 seconds. A wide QRS (>0.12 seconds) suggests bundle branch block or
ventricular origin.
Q3. The T-wave on an ECG represents which electrical event?
A. Atrial depolarization
B. Ventricular depolarization
C. SA node recovery
D. Ventricular repolarization
E. AV node conduction
Correct Answer: D. Ventricular repolarization
, EXPERT RATIONALE: The T-wave represents ventricular repolarization — the
recovery phase of the ventricles preparing for the next depolarization. T-wave
changes (inversion, peaked, flattened) are clinically significant in ischemia,
hyperkalemia, and other conditions.
Q4. What is the normal heart rate range for a sinus rhythm?
A. 40 – 59 bpm
B. 60 – 100 bpm
C. 101 – 120 bpm
D. 120 – 150 bpm
E. 150 – 200 bpm
Correct Answer: B. 60 – 100 bpm
EXPERT RATIONALE: Normal sinus rhythm (NSR) has a rate of 60–100 bpm. The
SA node is the dominant pacemaker and produces regular P waves followed by QRS
complexes. Rates below 60 bpm constitute sinus bradycardia; rates above 100 bpm
constitute sinus tachycardia.
Q5. On standard ECG paper, one small box represents how many seconds?
A. 0.04 seconds
B. 0.10 seconds
C. 0.20 seconds
D. 0.40 seconds
E. 1.00 second
Correct Answer: A. 0.04 seconds
EXPERT RATIONALE: Standard ECG paper runs at 25 mm/sec. Each small box is
1 mm wide, equaling 0.04 seconds. Each large box (5 small boxes) equals 0.20
, seconds. Five large boxes equal 1.0 second. This is fundamental to all interval
measurements.
Q6. How many small boxes make up one large box on ECG paper?
A. 2
B. 3
C. 4
D. 5
E. 6
Correct Answer: D. 5
EXPERT RATIONALE: One large box on ECG paper contains 5 small boxes. Each
small box = 0.04 seconds; each large box = 0.20 seconds. Voltage is measured
vertically: 1 small box = 0.1 mV; 1 large box = 0.5 mV.
Q7. A patient has a heart rate of 45 bpm and regular rhythm. P waves precede
each QRS. What rhythm is this most likely?
A. Junctional rhythm
B. Sinus bradycardia
C. Second-degree AV block type I
D. Third-degree AV block
E. Accelerated idioventricular rhythm
Correct Answer: B. Sinus bradycardia
EXPERT RATIONALE: Sinus bradycardia is defined as a heart rate below 60 bpm
with P waves preceding each QRS complex, indicating the SA node is the
pacemaker. It can be normal (athletes) or pathological (hypothyroidism, increased
vagal tone, beta-blockers).
& Nursing) Study Guide 2026/2027 | High-
Yield ECG Practice Questions, Rhythm
Interpretation & Detailed Rationales
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
━━━━━━━━━━━
SHARP EKG (ECG INTERPRETATION, CARDIOLOGY & NURSING)
STUDY GUIDE 2026/2027
High-Yield ECG Practice Questions, Rhythm Interpretation
& Detailed EXPERT RATIONALE
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
OVERVIEW
• This guide delivers 200 high-yield, exam-ready ECG and cardiology nursing
questions with five options each, a clearly marked correct answer, and a clinically
grounded EXPERT RATIONALE — designed to sharpen your rhythm recognition
and critical thinking under real exam pressure.
• Study this material by reading the EXPERT RATIONALE for every question — right
or wrong — to reinforce the "why" behind each answer, building the pattern
recognition and nursing judgment that top scores and safe clinical practice both
demand.
Q1. What is the normal duration of a PR interval on a standard ECG?
A. 0.06 – 0.10 seconds
B. 0.12 – 0.20 seconds
C. 0.22 – 0.30 seconds
D. 0.30 – 0.40 seconds
,E. 0.40 – 0.50 seconds
Correct Answer: B. 0.12 – 0.20 seconds
EXPERT RATIONALE: The PR interval reflects conduction time from the SA node
through the atria and AV node to the ventricles. A normal PR interval is 0.12–0.20
seconds (3–5 small boxes on ECG paper). Values above 0.20 seconds indicate a first-
degree AV block.
Q2. What does the QRS complex represent on the ECG?
A. Atrial repolarization
B. Ventricular repolarization
C. Ventricular depolarization
D. Atrial depolarization
E. SA node firing
Correct Answer: C. Ventricular depolarization
EXPERT RATIONALE: The QRS complex represents the electrical depolarization
of the ventricles, which triggers ventricular contraction. Normal QRS duration is
0.06–0.10 seconds. A wide QRS (>0.12 seconds) suggests bundle branch block or
ventricular origin.
Q3. The T-wave on an ECG represents which electrical event?
A. Atrial depolarization
B. Ventricular depolarization
C. SA node recovery
D. Ventricular repolarization
E. AV node conduction
Correct Answer: D. Ventricular repolarization
, EXPERT RATIONALE: The T-wave represents ventricular repolarization — the
recovery phase of the ventricles preparing for the next depolarization. T-wave
changes (inversion, peaked, flattened) are clinically significant in ischemia,
hyperkalemia, and other conditions.
Q4. What is the normal heart rate range for a sinus rhythm?
A. 40 – 59 bpm
B. 60 – 100 bpm
C. 101 – 120 bpm
D. 120 – 150 bpm
E. 150 – 200 bpm
Correct Answer: B. 60 – 100 bpm
EXPERT RATIONALE: Normal sinus rhythm (NSR) has a rate of 60–100 bpm. The
SA node is the dominant pacemaker and produces regular P waves followed by QRS
complexes. Rates below 60 bpm constitute sinus bradycardia; rates above 100 bpm
constitute sinus tachycardia.
Q5. On standard ECG paper, one small box represents how many seconds?
A. 0.04 seconds
B. 0.10 seconds
C. 0.20 seconds
D. 0.40 seconds
E. 1.00 second
Correct Answer: A. 0.04 seconds
EXPERT RATIONALE: Standard ECG paper runs at 25 mm/sec. Each small box is
1 mm wide, equaling 0.04 seconds. Each large box (5 small boxes) equals 0.20
, seconds. Five large boxes equal 1.0 second. This is fundamental to all interval
measurements.
Q6. How many small boxes make up one large box on ECG paper?
A. 2
B. 3
C. 4
D. 5
E. 6
Correct Answer: D. 5
EXPERT RATIONALE: One large box on ECG paper contains 5 small boxes. Each
small box = 0.04 seconds; each large box = 0.20 seconds. Voltage is measured
vertically: 1 small box = 0.1 mV; 1 large box = 0.5 mV.
Q7. A patient has a heart rate of 45 bpm and regular rhythm. P waves precede
each QRS. What rhythm is this most likely?
A. Junctional rhythm
B. Sinus bradycardia
C. Second-degree AV block type I
D. Third-degree AV block
E. Accelerated idioventricular rhythm
Correct Answer: B. Sinus bradycardia
EXPERT RATIONALE: Sinus bradycardia is defined as a heart rate below 60 bpm
with P waves preceding each QRS complex, indicating the SA node is the
pacemaker. It can be normal (athletes) or pathological (hypothyroidism, increased
vagal tone, beta-blockers).
