COMPREHENSIVE BASIC DYSRHYTHMIA
EXAMINATION
RELIAS DYSRHYTHIA
BASIC TEST ANSWERS
2026/2027
DYSRHYTHMIA – BASIC A (A+ GRADED 100% VERIFIED)
A complete 100-question basic dysrhythmia examination
with verified answers and detailed rationales, aligned
with Relias Dysrhythmia Testing Standards, AHA
Guidelines for Cardiac Monitoring, and Basic
Electrocardiogram Interpretation Competencies.
Cardiovascular Nursing & Telemetry Education
Cardiac Anatomy · EKG Measurements · Sinus Rhythms · Atrial ·
Junctional · Ventricular · AV Blocks
2026/ 2027 ED I TI ON · 100 QUESTI ONS · 8 SEC TI ONS ·
A N SW E RS W I TH RATI O N A L E S
, Section 1: Cardiac Anatomy & Electrophysiology
Q1: Which structure serves as the primary pacemaker of the normal heart, initiating each electrical
impulse at an intrinsic rate of 60 to 100 beats per minute?
A. The atrioventricular (AV) node
B. The sinoatrial (SA) node *[CORRECT]*
C. The bundle of His
D. The Purkinje fibers
Correct Answer: B
Rationale: The SA node is the heart's dominant pacemaker, discharging at an intrinsic rate of 60-100 beats per
minute and normally controlling the entire rhythm. The AV node is only the secondary pacemaker at 40-60 beats per
minute, and the bundle of His and Purkinje fibers fire far more slowly at 20-40 beats per minute. Relias
methodology teaches that the fastest functioning pacemaker always controls the rhythm, which is why the healthy
SA node suppresses all lower pacemakers.
Q2: What is the correct sequence of impulse conduction through the normal cardiac conduction
system?
A. SA node -> bundle of His -> AV node -> Purkinje fibers -> bundle branches
B. SA node -> AV node -> bundle of His -> bundle branches -> Purkinje fibers *[CORRECT]*
C. AV node -> SA node -> bundle branches -> bundle of His -> Purkinje fibers
D. SA node -> Purkinje fibers -> bundle branches -> AV node -> bundle of His
Correct Answer: B
Rationale: The impulse normally originates in the SA node, depolarizes the atria (producing the P wave), is briefly
delayed in the AV node, then travels through the bundle of His, the right and left bundle branches, and finally the
Purkinje fibers to depolarize the ventricles (the QRS complex). Every other option places a structure out of order,
which would be physiologically impossible. This pathway is the foundation of Relias rhythm analysis because each
structure corresponds to a specific waveform component.
Q3: A nursing student asks the telemetry nurse why the electrical impulse is briefly delayed as it
passes through the AV node. What is the physiological purpose of this delay?
A. It conserves the electrical energy of the SA node
B. It prevents the ventricles from contracting too forcefully
C. It allows the ventricles to repolarize before the next beat
D. It allows the atria to contract and complete ventricular filling before ventricular depolarization
*[CORRECT]*
Correct Answer: D
Rationale: The AV node delay of approximately 0.1 second lets atrial contraction finish, contributing the atrial kick
that supplies roughly 20-30 percent of ventricular filling. Without this delay, atrial contraction would occur
simultaneously with ventricular depolarization and stroke volume would fall. The delay has no role in contraction
force, ventricular repolarization, or energy conservation, so the other options misstate the physiology.
Dysrhythmia - Basic A | 2026/2027 Edition 1
, Q4: If the SA node fails to fire, the AV junction typically takes over as the backup pacemaker.
What is the intrinsic firing rate of AV junctional tissue?
A. 20 to 40 beats per minute
B. 40 to 60 beats per minute *[CORRECT]*
C. 60 to 100 beats per minute
D. 100 to 150 beats per minute
Correct Answer: B
Rationale: The pacemaker hierarchy descends from the SA node at 60-100, to the AV junction at 40-60, to the
ventricular Purkinje system at 20-40 beats per minute. Each successively lower pacemaker is slower, which protects
the patient by providing an escape rhythm when higher pacemakers fail. A rate of 20-40 identifies a ventricular
escape rhythm, while 60-100 describes the SA node range.
Q5: During phase 0 of the ventricular cardiac action potential, which ionic event produces the
rapid depolarization spike?
A. Influx of chloride ions into the cell
B. Slow influx of calcium ions into the cell
C. Efflux of potassium ions out of the cell
D. Rapid influx of sodium ions into the cell *[CORRECT]*
Correct Answer: D
Rationale: Phase 0 is the rapid depolarization phase, produced by fast sodium channels that flood the cell with
sodium ions. Slow calcium influx occurs in phase 2, the plateau, and potassium efflux drives phase 3 repolarization.
Chloride plays no primary role in phase 0, so it is a classic distractor in Relias action-potential questions.
Q6: Which phase of the cardiac action potential corresponds to the plateau period, during which
slow calcium influx balances potassium efflux?
A. Phase 4
B. Phase 1
C. Phase 3
D. Phase 2 *[CORRECT]*
Correct Answer: D
Rationale: Phase 2 is the plateau, where slow calcium channels hold the membrane potential near zero while
potassium slowly leaves the cell. This prolonged plateau is what gives cardiac muscle its long refractory period and
corresponds electrically to the ST segment. Phase 1 is early rapid repolarization, phase 3 is rapid repolarization, and
phase 4 is the resting or diastolic phase.
Dysrhythmia - Basic A | 2026/2027 Edition 2
, Q7: A patient's monitor shows a PVC falling on the downslope of the preceding T wave (R-on-T
phenomenon). Which property of the recovering myocardium explains why this finding is
dangerous?
A. Sodium channels are held fully open throughout repolarization
B. The atria have not yet been depolarized at that moment
C. The myocardium is in its relative refractory period and is vulnerable to re-entry dysrhythmias
*[CORRECT]*
D. The T wave represents atrial repolarization and cannot be interrupted
Correct Answer: C
Rationale: During the relative refractory period, corresponding to the downslope of the T wave, myocardial cells
have recovered unevenly, so a premature impulse can encounter excitable tissue and circle back through refractory
tissue, triggering re-entry ventricular tachycardia or ventricular fibrillation. This is the mechanism that makes
R-on-T a true warning sign on telemetry. The atria are irrelevant to this ventricular event, sodium channels are
largely inactive during repolarization, and the T wave represents ventricular repolarization, not atrial.
Q8: During which portion of the cardiac cycle is the ventricular myocardium in its absolute
refractory period, meaning no stimulus, no matter how strong, can generate another action
potential?
A. During the entire diastolic filling period
B. From the onset of the QRS complex to approximately the peak of the T wave *[CORRECT]*
C. Only during the duration of the P wave
D. From the end of the T wave to the beginning of the next P wave
Correct Answer: B
Rationale: The absolute refractory period spans phases 0 through early phase 3, which is represented on the EKG
from the start of the QRS complex to roughly the peak of the T wave. This long refractory window prevents tetanic
contraction of the heart. Diastole and the interval after the T wave correspond to the relative or fully recovered state,
which is precisely when the myocardium can be re-excited, and the P wave reflects atrial depolarization rather than
ventricular refractoriness.
Q9: On the EKG, ventricular repolarization is represented by which waveform component?
A. The P wave
B. The T wave *[CORRECT]*
C. The QRS complex
D. The U wave
Correct Answer: B
Rationale: The T wave represents ventricular repolarization, while the P wave is atrial depolarization and the QRS
complex is ventricular depolarization. Atrial repolarization also occurs but is buried within the larger QRS and is not
seen. The U wave is a small deflection after the T wave associated with Purkinje repolarization and prominence in
hypokalemia, so it is not the primary repolarization wave.
Dysrhythmia - Basic A | 2026/2027 Edition 3
EXAMINATION
RELIAS DYSRHYTHIA
BASIC TEST ANSWERS
2026/2027
DYSRHYTHMIA – BASIC A (A+ GRADED 100% VERIFIED)
A complete 100-question basic dysrhythmia examination
with verified answers and detailed rationales, aligned
with Relias Dysrhythmia Testing Standards, AHA
Guidelines for Cardiac Monitoring, and Basic
Electrocardiogram Interpretation Competencies.
Cardiovascular Nursing & Telemetry Education
Cardiac Anatomy · EKG Measurements · Sinus Rhythms · Atrial ·
Junctional · Ventricular · AV Blocks
2026/ 2027 ED I TI ON · 100 QUESTI ONS · 8 SEC TI ONS ·
A N SW E RS W I TH RATI O N A L E S
, Section 1: Cardiac Anatomy & Electrophysiology
Q1: Which structure serves as the primary pacemaker of the normal heart, initiating each electrical
impulse at an intrinsic rate of 60 to 100 beats per minute?
A. The atrioventricular (AV) node
B. The sinoatrial (SA) node *[CORRECT]*
C. The bundle of His
D. The Purkinje fibers
Correct Answer: B
Rationale: The SA node is the heart's dominant pacemaker, discharging at an intrinsic rate of 60-100 beats per
minute and normally controlling the entire rhythm. The AV node is only the secondary pacemaker at 40-60 beats per
minute, and the bundle of His and Purkinje fibers fire far more slowly at 20-40 beats per minute. Relias
methodology teaches that the fastest functioning pacemaker always controls the rhythm, which is why the healthy
SA node suppresses all lower pacemakers.
Q2: What is the correct sequence of impulse conduction through the normal cardiac conduction
system?
A. SA node -> bundle of His -> AV node -> Purkinje fibers -> bundle branches
B. SA node -> AV node -> bundle of His -> bundle branches -> Purkinje fibers *[CORRECT]*
C. AV node -> SA node -> bundle branches -> bundle of His -> Purkinje fibers
D. SA node -> Purkinje fibers -> bundle branches -> AV node -> bundle of His
Correct Answer: B
Rationale: The impulse normally originates in the SA node, depolarizes the atria (producing the P wave), is briefly
delayed in the AV node, then travels through the bundle of His, the right and left bundle branches, and finally the
Purkinje fibers to depolarize the ventricles (the QRS complex). Every other option places a structure out of order,
which would be physiologically impossible. This pathway is the foundation of Relias rhythm analysis because each
structure corresponds to a specific waveform component.
Q3: A nursing student asks the telemetry nurse why the electrical impulse is briefly delayed as it
passes through the AV node. What is the physiological purpose of this delay?
A. It conserves the electrical energy of the SA node
B. It prevents the ventricles from contracting too forcefully
C. It allows the ventricles to repolarize before the next beat
D. It allows the atria to contract and complete ventricular filling before ventricular depolarization
*[CORRECT]*
Correct Answer: D
Rationale: The AV node delay of approximately 0.1 second lets atrial contraction finish, contributing the atrial kick
that supplies roughly 20-30 percent of ventricular filling. Without this delay, atrial contraction would occur
simultaneously with ventricular depolarization and stroke volume would fall. The delay has no role in contraction
force, ventricular repolarization, or energy conservation, so the other options misstate the physiology.
Dysrhythmia - Basic A | 2026/2027 Edition 1
, Q4: If the SA node fails to fire, the AV junction typically takes over as the backup pacemaker.
What is the intrinsic firing rate of AV junctional tissue?
A. 20 to 40 beats per minute
B. 40 to 60 beats per minute *[CORRECT]*
C. 60 to 100 beats per minute
D. 100 to 150 beats per minute
Correct Answer: B
Rationale: The pacemaker hierarchy descends from the SA node at 60-100, to the AV junction at 40-60, to the
ventricular Purkinje system at 20-40 beats per minute. Each successively lower pacemaker is slower, which protects
the patient by providing an escape rhythm when higher pacemakers fail. A rate of 20-40 identifies a ventricular
escape rhythm, while 60-100 describes the SA node range.
Q5: During phase 0 of the ventricular cardiac action potential, which ionic event produces the
rapid depolarization spike?
A. Influx of chloride ions into the cell
B. Slow influx of calcium ions into the cell
C. Efflux of potassium ions out of the cell
D. Rapid influx of sodium ions into the cell *[CORRECT]*
Correct Answer: D
Rationale: Phase 0 is the rapid depolarization phase, produced by fast sodium channels that flood the cell with
sodium ions. Slow calcium influx occurs in phase 2, the plateau, and potassium efflux drives phase 3 repolarization.
Chloride plays no primary role in phase 0, so it is a classic distractor in Relias action-potential questions.
Q6: Which phase of the cardiac action potential corresponds to the plateau period, during which
slow calcium influx balances potassium efflux?
A. Phase 4
B. Phase 1
C. Phase 3
D. Phase 2 *[CORRECT]*
Correct Answer: D
Rationale: Phase 2 is the plateau, where slow calcium channels hold the membrane potential near zero while
potassium slowly leaves the cell. This prolonged plateau is what gives cardiac muscle its long refractory period and
corresponds electrically to the ST segment. Phase 1 is early rapid repolarization, phase 3 is rapid repolarization, and
phase 4 is the resting or diastolic phase.
Dysrhythmia - Basic A | 2026/2027 Edition 2
, Q7: A patient's monitor shows a PVC falling on the downslope of the preceding T wave (R-on-T
phenomenon). Which property of the recovering myocardium explains why this finding is
dangerous?
A. Sodium channels are held fully open throughout repolarization
B. The atria have not yet been depolarized at that moment
C. The myocardium is in its relative refractory period and is vulnerable to re-entry dysrhythmias
*[CORRECT]*
D. The T wave represents atrial repolarization and cannot be interrupted
Correct Answer: C
Rationale: During the relative refractory period, corresponding to the downslope of the T wave, myocardial cells
have recovered unevenly, so a premature impulse can encounter excitable tissue and circle back through refractory
tissue, triggering re-entry ventricular tachycardia or ventricular fibrillation. This is the mechanism that makes
R-on-T a true warning sign on telemetry. The atria are irrelevant to this ventricular event, sodium channels are
largely inactive during repolarization, and the T wave represents ventricular repolarization, not atrial.
Q8: During which portion of the cardiac cycle is the ventricular myocardium in its absolute
refractory period, meaning no stimulus, no matter how strong, can generate another action
potential?
A. During the entire diastolic filling period
B. From the onset of the QRS complex to approximately the peak of the T wave *[CORRECT]*
C. Only during the duration of the P wave
D. From the end of the T wave to the beginning of the next P wave
Correct Answer: B
Rationale: The absolute refractory period spans phases 0 through early phase 3, which is represented on the EKG
from the start of the QRS complex to roughly the peak of the T wave. This long refractory window prevents tetanic
contraction of the heart. Diastole and the interval after the T wave correspond to the relative or fully recovered state,
which is precisely when the myocardium can be re-excited, and the P wave reflects atrial depolarization rather than
ventricular refractoriness.
Q9: On the EKG, ventricular repolarization is represented by which waveform component?
A. The P wave
B. The T wave *[CORRECT]*
C. The QRS complex
D. The U wave
Correct Answer: B
Rationale: The T wave represents ventricular repolarization, while the P wave is atrial depolarization and the QRS
complex is ventricular depolarization. Atrial repolarization also occurs but is buried within the larger QRS and is not
seen. The U wave is a small deflection after the T wave associated with Purkinje repolarization and prominence in
hypokalemia, so it is not the primary repolarization wave.
Dysrhythmia - Basic A | 2026/2027 Edition 3
