Basic Arrhythmia Practice Questions and Rationales (pdf) |
2026/2027 | Cardiac Arrhythmias Q&A | Nursing
NURSING AND TELEMETRY REVIEW
Basic Arrhythmia
Questions and Rationales
Companion to BASIC ARRHYTHMIA Sentara
37 Multiple Choice Questions
Correct Answers and Detailed Rationales
ECG Foundations • Sinus Rhythms • Atrial Rhythms
Junctional Rhythms • Ventricular Rhythms • AV Blocks
2026 Study Edition
Independent educational study resource
For rhythm recognition and exam preparation
,Basic Arrhythmia Questions and Rationales
Companion to BASIC ARRHYTHMIA Sentara
Review adult ECG timing, sinus and ectopic rhythms, cardiac arrest rhythms and atrioventricular blocks. Each
original prompt is preserved, with four answer choices, a marked answer and an explanatory rationale. Unless
stated otherwise, ECG timing assumes a paper speed of 25 mm per second.
Independent study resource. The supplied title is retained for identification; institutional authorship or
endorsement has not been verified. Use the patient assessment and current local protocols alongside rhythm
interpretation.
How to use this review
Select one best answer before reading the explanation. Distinguish defining rhythm features from typical rate
ranges. Electrical activity on a monitor does not establish a pulse. No ECG strips were included in the source, so
these questions assess descriptive recognition.
ECG foundations
1. 5 steps to EKG Interpretation
A. Assess P waves and their relationship to QRS complexes; measure PR; measure QRS; assess regularity;
calculate rate
B. Measure rate only
C. Assess T waves only
D. Diagnose from QRS width alone
Correct answer: A. Assess P waves and their relationship to QRS complexes; measure PR; measure QRS;
assess regularity; calculate rate
Expert rationale: A consistent sequence reduces missed conduction abnormalities. P waves help identify atrial
activation, PR evaluates atrioventricular conduction, QRS assesses ventricular activation, and regularity and
rate characterize the rhythm. Rate alone cannot identify origin or block; T waves alone cannot establish the
rhythm; width alone cannot distinguish all wide complex causes. Also review QT or QTc and the patient’s
condition because repolarization abnormalities have clinical significance.
2. PR interval length
A. 0.04 seconds
B. 0.12 to 0.20 seconds in standard adult rhythm teaching
C. 0.30 to 0.40 seconds
D. Always less than 0.08 seconds
Correct answer: B. 0.12 to 0.20 seconds in standard adult rhythm teaching
Expert rationale: Measure from the start of P to the start of QRS. The teaching range is 0.12 to 0.20 seconds;
0.04 is one small box at standard speed. A PR of 0.30 to 0.40 is prolonged, while a PR below 0.08 is unusually
short. A prolonged constant PR with every P conducted supports first degree AV block.
2
,3. QRS Interval length
A. 0.12 to 0.20 seconds as the normal narrow range
B. 0.32 to 0.44 seconds
C. Usually about 0.06 to 0.10 seconds and less than 0.12 seconds for a narrow QRS
D. Always greater than 0.20 seconds
Correct answer: C. Usually about 0.06 to 0.10 seconds and less than 0.12 seconds for a narrow QRS
Expert rationale: Measure from the first QRS deflection to its end. The key narrow versus wide threshold is 0.12
seconds: a QRS at or above this is wide. The source’s upper value of 0.12 should not be treated as definitely
normal. The PR range describes atrioventricular conduction, and 0.32 to 0.44 is not a QRS range. A QRS above
0.20 is markedly prolonged.
4. QT Interval length
A. Always 0.32 to 0.44 seconds regardless of rate
B. Always 0.12 to 0.20 seconds
C. Always exactly 0.04 seconds
D. Varies with heart rate; assess the heart rate corrected QT interval rather than a fixed raw QT range
Correct answer: D. Varies with heart rate; assess the heart rate corrected QT interval rather than a fixed raw
QT range
Expert rationale: QT extends from QRS onset to the end of T and shortens as heart rate increases. A fixed raw
range can misclassify repolarization. QTc interpretation also depends on sex, correction formula and clinical
context. The 0.12 to 0.20 range belongs to PR, and 0.04 is one small box. QT prolongation matters when
evaluating torsades risk.
5. Length of small squares on EKG
A. 0.04 seconds at 25 mm per second
B. 0.20 seconds at 25 mm per second
C. 1 second at 25 mm per second
D. 0.40 seconds at 25 mm per second
Correct answer: A. 0.04 seconds at 25 mm per second
Expert rationale: One small horizontal box is 1 mm; 1 divided by 25 equals 0.04 seconds. A large box is 0.20
seconds. One second spans 25 small boxes, and 0.40 seconds spans 10. Check paper speed: at 50 mm per
second a small box represents 0.02 seconds.
3
, 6. Length of regular squares on EKG
A. 0.04 seconds for one large box
B. 0.20 seconds for one large box at 25 mm per second
C. 0.50 seconds for one large box
D. 1 second for one large box
Correct answer: B. 0.20 seconds for one large box at 25 mm per second
Expert rationale: Here regular squares means the large 5 mm squares. Five small boxes times 0.04 equals 0.20
seconds. A value of 0.04 belongs to a small box; 0.50 and 1 second are longer spans. Timing refers to the
horizontal axis; vertical boxes measure voltage.
7. P wave represents
A. Atrial repolarization
B. Ventricular depolarization
C. Atrial depolarization
D. Ventricular repolarization
Correct answer: C. Atrial depolarization
Expert rationale: The P wave records atrial electrical activation, which normally precedes atrial contraction. It
does not directly measure contraction. Atrial repolarization is usually obscured by QRS; ventricular
depolarization forms QRS, and ventricular repolarization forms T.
8. QRS represents
A. Atrial depolarization
B. Ventricular repolarization
C. Mechanical ejection of blood alone
D. Ventricular depolarization
Correct answer: D. Ventricular depolarization
Expert rationale: QRS represents electrical activation of the ventricles. Contraction follows but electrical activity
does not guarantee an effective pulse. P represents atrial depolarization and T represents ventricular
repolarization. Mechanical ejection requires clinical or hemodynamic assessment.
9. QTI represents
A. The interval encompassing ventricular depolarization and repolarization
B. The inherent firing rate of Purkinje fibers
C. Atrial depolarization alone
D. The time between successive P waves
Correct answer: A. The interval encompassing ventricular depolarization and repolarization
Expert rationale: QTI means QT interval and extends from QRS onset to the end of T. The supplied answer
incorrectly identifies it as a Purkinje firing rate; a pacemaker rate is expressed in beats per minute, not as this
interval. P represents atrial depolarization, and the P to P interval measures atrial cycle length.
4
2026/2027 | Cardiac Arrhythmias Q&A | Nursing
NURSING AND TELEMETRY REVIEW
Basic Arrhythmia
Questions and Rationales
Companion to BASIC ARRHYTHMIA Sentara
37 Multiple Choice Questions
Correct Answers and Detailed Rationales
ECG Foundations • Sinus Rhythms • Atrial Rhythms
Junctional Rhythms • Ventricular Rhythms • AV Blocks
2026 Study Edition
Independent educational study resource
For rhythm recognition and exam preparation
,Basic Arrhythmia Questions and Rationales
Companion to BASIC ARRHYTHMIA Sentara
Review adult ECG timing, sinus and ectopic rhythms, cardiac arrest rhythms and atrioventricular blocks. Each
original prompt is preserved, with four answer choices, a marked answer and an explanatory rationale. Unless
stated otherwise, ECG timing assumes a paper speed of 25 mm per second.
Independent study resource. The supplied title is retained for identification; institutional authorship or
endorsement has not been verified. Use the patient assessment and current local protocols alongside rhythm
interpretation.
How to use this review
Select one best answer before reading the explanation. Distinguish defining rhythm features from typical rate
ranges. Electrical activity on a monitor does not establish a pulse. No ECG strips were included in the source, so
these questions assess descriptive recognition.
ECG foundations
1. 5 steps to EKG Interpretation
A. Assess P waves and their relationship to QRS complexes; measure PR; measure QRS; assess regularity;
calculate rate
B. Measure rate only
C. Assess T waves only
D. Diagnose from QRS width alone
Correct answer: A. Assess P waves and their relationship to QRS complexes; measure PR; measure QRS;
assess regularity; calculate rate
Expert rationale: A consistent sequence reduces missed conduction abnormalities. P waves help identify atrial
activation, PR evaluates atrioventricular conduction, QRS assesses ventricular activation, and regularity and
rate characterize the rhythm. Rate alone cannot identify origin or block; T waves alone cannot establish the
rhythm; width alone cannot distinguish all wide complex causes. Also review QT or QTc and the patient’s
condition because repolarization abnormalities have clinical significance.
2. PR interval length
A. 0.04 seconds
B. 0.12 to 0.20 seconds in standard adult rhythm teaching
C. 0.30 to 0.40 seconds
D. Always less than 0.08 seconds
Correct answer: B. 0.12 to 0.20 seconds in standard adult rhythm teaching
Expert rationale: Measure from the start of P to the start of QRS. The teaching range is 0.12 to 0.20 seconds;
0.04 is one small box at standard speed. A PR of 0.30 to 0.40 is prolonged, while a PR below 0.08 is unusually
short. A prolonged constant PR with every P conducted supports first degree AV block.
2
,3. QRS Interval length
A. 0.12 to 0.20 seconds as the normal narrow range
B. 0.32 to 0.44 seconds
C. Usually about 0.06 to 0.10 seconds and less than 0.12 seconds for a narrow QRS
D. Always greater than 0.20 seconds
Correct answer: C. Usually about 0.06 to 0.10 seconds and less than 0.12 seconds for a narrow QRS
Expert rationale: Measure from the first QRS deflection to its end. The key narrow versus wide threshold is 0.12
seconds: a QRS at or above this is wide. The source’s upper value of 0.12 should not be treated as definitely
normal. The PR range describes atrioventricular conduction, and 0.32 to 0.44 is not a QRS range. A QRS above
0.20 is markedly prolonged.
4. QT Interval length
A. Always 0.32 to 0.44 seconds regardless of rate
B. Always 0.12 to 0.20 seconds
C. Always exactly 0.04 seconds
D. Varies with heart rate; assess the heart rate corrected QT interval rather than a fixed raw QT range
Correct answer: D. Varies with heart rate; assess the heart rate corrected QT interval rather than a fixed raw
QT range
Expert rationale: QT extends from QRS onset to the end of T and shortens as heart rate increases. A fixed raw
range can misclassify repolarization. QTc interpretation also depends on sex, correction formula and clinical
context. The 0.12 to 0.20 range belongs to PR, and 0.04 is one small box. QT prolongation matters when
evaluating torsades risk.
5. Length of small squares on EKG
A. 0.04 seconds at 25 mm per second
B. 0.20 seconds at 25 mm per second
C. 1 second at 25 mm per second
D. 0.40 seconds at 25 mm per second
Correct answer: A. 0.04 seconds at 25 mm per second
Expert rationale: One small horizontal box is 1 mm; 1 divided by 25 equals 0.04 seconds. A large box is 0.20
seconds. One second spans 25 small boxes, and 0.40 seconds spans 10. Check paper speed: at 50 mm per
second a small box represents 0.02 seconds.
3
, 6. Length of regular squares on EKG
A. 0.04 seconds for one large box
B. 0.20 seconds for one large box at 25 mm per second
C. 0.50 seconds for one large box
D. 1 second for one large box
Correct answer: B. 0.20 seconds for one large box at 25 mm per second
Expert rationale: Here regular squares means the large 5 mm squares. Five small boxes times 0.04 equals 0.20
seconds. A value of 0.04 belongs to a small box; 0.50 and 1 second are longer spans. Timing refers to the
horizontal axis; vertical boxes measure voltage.
7. P wave represents
A. Atrial repolarization
B. Ventricular depolarization
C. Atrial depolarization
D. Ventricular repolarization
Correct answer: C. Atrial depolarization
Expert rationale: The P wave records atrial electrical activation, which normally precedes atrial contraction. It
does not directly measure contraction. Atrial repolarization is usually obscured by QRS; ventricular
depolarization forms QRS, and ventricular repolarization forms T.
8. QRS represents
A. Atrial depolarization
B. Ventricular repolarization
C. Mechanical ejection of blood alone
D. Ventricular depolarization
Correct answer: D. Ventricular depolarization
Expert rationale: QRS represents electrical activation of the ventricles. Contraction follows but electrical activity
does not guarantee an effective pulse. P represents atrial depolarization and T represents ventricular
repolarization. Mechanical ejection requires clinical or hemodynamic assessment.
9. QTI represents
A. The interval encompassing ventricular depolarization and repolarization
B. The inherent firing rate of Purkinje fibers
C. Atrial depolarization alone
D. The time between successive P waves
Correct answer: A. The interval encompassing ventricular depolarization and repolarization
Expert rationale: QTI means QT interval and extends from QRS onset to the end of T. The supplied answer
incorrectly identifies it as a Purkinje firing rate; a pacemaker rate is expressed in beats per minute, not as this
interval. P represents atrial depolarization, and the P to P interval measures atrial cycle length.
4
