Relias Dysrhythmia Basic Test | Latest Update 2026/2027 |
200 Practice Questions & Verified Answers | Basic A
Dysrhythmia | A+ Graded
1. A nurse is reviewing an ECG strip. To accurately calculate the ventricular rate for a regular rhythm,
which method is most precise?
A. Count the number of QRS complexes in a 6second strip and multiply by 10.
B. Divide 300 by the number of large boxes between two R waves (RR interval).
C. Count the number of small boxes between two R waves and divide by 1500.
D. Multiply the number of P waves by 10.
Answer: B. Divide 300 by the number of large boxes between two R waves (RR interval).
Explanation: For regular rhythms, the "300 method" (300 ÷ number of large boxes between R waves) is
highly accurate. A 6second count (Option A) is best for irregular rhythms. Option C is formulaic but less
efficient clinically. Option D calculates atrial rate, not ventricular.
2. A student nurse asks what the "PR interval" represents electrically. What is the correct physiological
explanation?
A. Time from ventricular depolarization to repolarization
B. Time from atrial depolarization to ventricular depolarization
C. Time of ventricular depolarization
D. Time of atrial depolarization only
Answer: B. Time from atrial depolarization to ventricular depolarization.
,Explanation: The PR interval represents the time from the onset of atrial depolarization (P wave) to the
onset of ventricular depolarization (QRS complex). It reflects conduction through the AV node, bundle of
His, and Purkinje fibers.
3. A patient's ECG shows a prolonged QT interval. The nurse understands this places the patient at
highest risk for which dysrhythmia?
A. Atrial fibrillation
B. Supraventricular tachycardia
C. Torsade de Pointes
D. Asystole
Answer: C. Torsade de Pointes.
Explanation: A prolonged QT interval indicates that the ventricles are taking too long to repolarize. This
heterogeneity in repolarization creates an "R on T" phenomenon risk, specifically precipitating Torsade
de Pointes (polymorphic ventricular tachycardia).
4. To properly assess the regularity of a cardiac rhythm, the nurse should:
A. Measure the PP interval and see if it is consistent.
B. Measure the RR interval using calipers across the strip.
C. Count the number of P waves per QRS complex.
D. Look for the presence of U waves.
Answer: B. Measure the RR interval using calipers across the strip.
,Explanation: Regularity is determined by the consistency of ventricular contraction timing. Using calipers
to compare the distance between successive RR intervals is the gold standard.
5. What is the normal PR interval duration?
A. 0.040.08 seconds
B. 0.120.20 seconds
C. 0.200.30 seconds
D. 0.300.40 seconds
Answer: B. 0.120.20 seconds.
Explanation: The normal PR interval is 0.120.20 seconds (35 small boxes). A PR interval >0.20 seconds
indicates firstdegree AV block.
6. What is the normal QRS duration?
A. Less than 0.06 seconds
B. Less than 0.12 seconds
C. Less than 0.20 seconds
D. Less than 0.24 seconds
Answer: B. Less than 0.12 seconds.
, Explanation: Normal QRS duration is <0.12 seconds (<3 small boxes). A QRS ≥0.12 seconds indicates
intraventricular conduction delay or bundle branch block.
7. The nurse understands that the "Sinus" node is the primary pacemaker because it has:
A. The slowest rate of automaticity.
B. The fastest rate of automaticity.
C. The ability to generate the largest electrical voltage.
D. The longest refractory period.
Answer: B. The fastest rate of automaticity.
Explanation: The SA node is the primary pacemaker because it has the fastest rate of automaticity
(60100 bpm) and overrides other potential pacemakers.
8. A patient's telemetry strip shows a heart rhythm with a P wave before every QRS complex. The P
waves are upright and uniform. The heart rate is 72 beats/min. What is the rhythm?
A. Sinus Bradycardia
B. Normal Sinus Rhythm
C. Sinus Tachycardia
D. Junctional Rhythm
Answer: B. Normal Sinus Rhythm.
200 Practice Questions & Verified Answers | Basic A
Dysrhythmia | A+ Graded
1. A nurse is reviewing an ECG strip. To accurately calculate the ventricular rate for a regular rhythm,
which method is most precise?
A. Count the number of QRS complexes in a 6second strip and multiply by 10.
B. Divide 300 by the number of large boxes between two R waves (RR interval).
C. Count the number of small boxes between two R waves and divide by 1500.
D. Multiply the number of P waves by 10.
Answer: B. Divide 300 by the number of large boxes between two R waves (RR interval).
Explanation: For regular rhythms, the "300 method" (300 ÷ number of large boxes between R waves) is
highly accurate. A 6second count (Option A) is best for irregular rhythms. Option C is formulaic but less
efficient clinically. Option D calculates atrial rate, not ventricular.
2. A student nurse asks what the "PR interval" represents electrically. What is the correct physiological
explanation?
A. Time from ventricular depolarization to repolarization
B. Time from atrial depolarization to ventricular depolarization
C. Time of ventricular depolarization
D. Time of atrial depolarization only
Answer: B. Time from atrial depolarization to ventricular depolarization.
,Explanation: The PR interval represents the time from the onset of atrial depolarization (P wave) to the
onset of ventricular depolarization (QRS complex). It reflects conduction through the AV node, bundle of
His, and Purkinje fibers.
3. A patient's ECG shows a prolonged QT interval. The nurse understands this places the patient at
highest risk for which dysrhythmia?
A. Atrial fibrillation
B. Supraventricular tachycardia
C. Torsade de Pointes
D. Asystole
Answer: C. Torsade de Pointes.
Explanation: A prolonged QT interval indicates that the ventricles are taking too long to repolarize. This
heterogeneity in repolarization creates an "R on T" phenomenon risk, specifically precipitating Torsade
de Pointes (polymorphic ventricular tachycardia).
4. To properly assess the regularity of a cardiac rhythm, the nurse should:
A. Measure the PP interval and see if it is consistent.
B. Measure the RR interval using calipers across the strip.
C. Count the number of P waves per QRS complex.
D. Look for the presence of U waves.
Answer: B. Measure the RR interval using calipers across the strip.
,Explanation: Regularity is determined by the consistency of ventricular contraction timing. Using calipers
to compare the distance between successive RR intervals is the gold standard.
5. What is the normal PR interval duration?
A. 0.040.08 seconds
B. 0.120.20 seconds
C. 0.200.30 seconds
D. 0.300.40 seconds
Answer: B. 0.120.20 seconds.
Explanation: The normal PR interval is 0.120.20 seconds (35 small boxes). A PR interval >0.20 seconds
indicates firstdegree AV block.
6. What is the normal QRS duration?
A. Less than 0.06 seconds
B. Less than 0.12 seconds
C. Less than 0.20 seconds
D. Less than 0.24 seconds
Answer: B. Less than 0.12 seconds.
, Explanation: Normal QRS duration is <0.12 seconds (<3 small boxes). A QRS ≥0.12 seconds indicates
intraventricular conduction delay or bundle branch block.
7. The nurse understands that the "Sinus" node is the primary pacemaker because it has:
A. The slowest rate of automaticity.
B. The fastest rate of automaticity.
C. The ability to generate the largest electrical voltage.
D. The longest refractory period.
Answer: B. The fastest rate of automaticity.
Explanation: The SA node is the primary pacemaker because it has the fastest rate of automaticity
(60100 bpm) and overrides other potential pacemakers.
8. A patient's telemetry strip shows a heart rhythm with a P wave before every QRS complex. The P
waves are upright and uniform. The heart rate is 72 beats/min. What is the rhythm?
A. Sinus Bradycardia
B. Normal Sinus Rhythm
C. Sinus Tachycardia
D. Junctional Rhythm
Answer: B. Normal Sinus Rhythm.
