Relias Dysrhythmia Basic A - 2025 - Complete
Practice Test with Verified Answers
1. A patient with no prior cardiac history presents with a regular, narrow-complex
tachycardia at 180 bpm. The rhythm strip shows no discernible P waves, and the QRS
duration is 0.08 seconds. A vagal maneuver is attempted without success. Which of the
following electrophysiological mechanisms most likely underlies this dysrhythmia?
A. Enhanced automaticity within the sinoatrial node
B. Reentrant circuit involving the atrioventricular node
C. Triggered activity from delayed afterdepolarizations in the ventricles
D. Abnormal automaticity from a Purkinje fiber focus
Answer: B
2. Which of the following findings on a 12-lead ECG is most consistent with acute
pericarditis rather than acute myocardial infarction?
A. ST-segment depression in leads V1-V3 with tall R waves
B. Diffuse ST-segment elevation with PR-segment depression in multiple leads
C. Pathologic Q waves in leads II, III, and aVF
D. Hyperacute T waves in leads V2-V4
Answer: B
3. A rhythm strip shows a regular wide-complex tachycardia at 200 bpm. The QRS
duration is 0.14 seconds. There is no clear relationship between P waves and QRS
complexes. The patient is hemodynamically unstable. Which of the following is the most
appropriate immediate intervention?
A. Administration of adenosine 6 mg rapid IV push
B. Synchronized cardioversion at 100 J
C. Administration of amiodarone 150 mg IV over 10 minutes
D. Immediate defibrillation at 200 J
Answer: B
4. A patient with a history of chronic obstructive pulmonary disease is admitted for
exacerbation. The telemetry monitor shows a rhythm with a ventricular rate of 110 bpm,
irregularly irregular rhythm, and no distinct P waves. The baseline appears undulating.
Which of the following is the most likely cause of this rhythm?
A. Increased vagal tone leading to atrial standstill
B. Multiple reentrant wavelets in the atria due to atrial enlargement
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,C. Focal automaticity from a pulmonary vein focus
D. Conduction block at the AV node with a junctional escape rhythm
Answer: B
5. A patient presents with syncope. An ECG reveals a prolonged QT interval (QTc = 520
ms) and episodes of polymorphic ventricular tachycardia that appear to be torsades de
pointes. Which of the following electrolyte abnormalities is most likely to precipitate this
dysrhythmia?
A. Hypercalcemia
B. Hypokalemia
C. Hypermagnesemia
D. Hypernatremia
Answer: B
6. A patient with an anterior ST-elevation myocardial infarction (STEMI) develops a
rhythm with a ventricular rate of 40 bpm, wide QRS complexes (0.16 seconds), and no P
waves. The patient is hypotensive and confused. Which of the following is the most
appropriate initial treatment?
A. Atropine 0.5 mg IV push
B. Transcutaneous pacing
C. Isoproterenol infusion
D. Implantable cardioverter-defibrillator placement
Answer: B
7. A rhythm strip shows a regular rhythm at 75 bpm with a PR interval of 0.24 seconds and
a QRS duration of 0.10 seconds. Which of the following conduction abnormalities is
present?
A. First-degree AV block
B. Mobitz type I second-degree AV block
C. Mobitz type II second-degree AV block
D. Left anterior fascicular block
Answer: A
8. A patient with a history of heart failure with reduced ejection fraction is on digoxin
therapy. The rhythm strip shows a regular atrial rate of 70 bpm, but the ventricular rate is
35 bpm and irregular, with grouped beating. The PR interval progressively lengthens
before a dropped QRS. Which of the following is the most likely cause?
A. Digoxin toxicity causing enhanced automaticity
B. Digoxin toxicity causing increased vagal tone and AV nodal blockade
C. Digoxin toxicity causing accelerated junctional rhythm
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, D. Digoxin toxicity causing ventricular bigeminy
Answer: B
9. A patient presents with palpitations. An ECG shows a narrow-complex tachycardia at
150 bpm with P waves that are inverted in leads II, III, and aVF. The P waves precede each
QRS with a PR interval of 0.12 seconds. Which of the following is the most likely origin of
the tachycardia?
A. Sinoatrial node
B. Atrioventricular node
C. Low atrial focus near the coronary sinus
D. Accessory pathway (Wolff-Parkinson-White syndrome)
Answer: C
10. A patient with a history of myocardial infarction has an ECG showing a wide QRS
(0.14 seconds) with an rSR' pattern in lead V1 and a wide, deep S wave in lead V6. The axis
is normal. Which of the following conduction abnormalities is most likely?
A. Left bundle branch block
B. Right bundle branch block
C. Left anterior fascicular block
D. Nonspecific intraventricular conduction delay
Answer: B
11. A patient presents with a wide QRS tachycardia at a rate of 180 bpm. The rhythm is
irregular, and you note that some QRS complexes appear narrower than others. Which of
the following mechanisms best explains this phenomenon?
A. Atrial fibrillation with pre-excitation via an accessory pathway, causing variable conduction to the
ventricles.
B. Ventricular tachycardia with intermittent fusion beats due to competing sinus node activity.
C. Supraventricular tachycardia with aberrancy that varies with the preceding R-R interval (Ashman
phenomenon).
D. Atrial flutter with variable block and intermittent bundle branch block due to rate-related aberrancy.
Answer: A
12. A patient's rhythm strip shows a regular narrow QRS tachycardia at 150 bpm with
visible P waves that are inverted in leads II, III, and aVF. The RP interval is longer than
the PR interval. Which of the following is the most likely diagnosis?
A. Atrioventricular nodal reentrant tachycardia (AVNRT), typical (slow-fast) form.
B. Atrioventricular reentrant tachycardia (AVRT) using a concealed accessory pathway.
C. Atrial tachycardia originating from the low right atrium near the coronary sinus.
D. Junctional ectopic tachycardia with retrograde atrial activation.
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Practice Test with Verified Answers
1. A patient with no prior cardiac history presents with a regular, narrow-complex
tachycardia at 180 bpm. The rhythm strip shows no discernible P waves, and the QRS
duration is 0.08 seconds. A vagal maneuver is attempted without success. Which of the
following electrophysiological mechanisms most likely underlies this dysrhythmia?
A. Enhanced automaticity within the sinoatrial node
B. Reentrant circuit involving the atrioventricular node
C. Triggered activity from delayed afterdepolarizations in the ventricles
D. Abnormal automaticity from a Purkinje fiber focus
Answer: B
2. Which of the following findings on a 12-lead ECG is most consistent with acute
pericarditis rather than acute myocardial infarction?
A. ST-segment depression in leads V1-V3 with tall R waves
B. Diffuse ST-segment elevation with PR-segment depression in multiple leads
C. Pathologic Q waves in leads II, III, and aVF
D. Hyperacute T waves in leads V2-V4
Answer: B
3. A rhythm strip shows a regular wide-complex tachycardia at 200 bpm. The QRS
duration is 0.14 seconds. There is no clear relationship between P waves and QRS
complexes. The patient is hemodynamically unstable. Which of the following is the most
appropriate immediate intervention?
A. Administration of adenosine 6 mg rapid IV push
B. Synchronized cardioversion at 100 J
C. Administration of amiodarone 150 mg IV over 10 minutes
D. Immediate defibrillation at 200 J
Answer: B
4. A patient with a history of chronic obstructive pulmonary disease is admitted for
exacerbation. The telemetry monitor shows a rhythm with a ventricular rate of 110 bpm,
irregularly irregular rhythm, and no distinct P waves. The baseline appears undulating.
Which of the following is the most likely cause of this rhythm?
A. Increased vagal tone leading to atrial standstill
B. Multiple reentrant wavelets in the atria due to atrial enlargement
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,C. Focal automaticity from a pulmonary vein focus
D. Conduction block at the AV node with a junctional escape rhythm
Answer: B
5. A patient presents with syncope. An ECG reveals a prolonged QT interval (QTc = 520
ms) and episodes of polymorphic ventricular tachycardia that appear to be torsades de
pointes. Which of the following electrolyte abnormalities is most likely to precipitate this
dysrhythmia?
A. Hypercalcemia
B. Hypokalemia
C. Hypermagnesemia
D. Hypernatremia
Answer: B
6. A patient with an anterior ST-elevation myocardial infarction (STEMI) develops a
rhythm with a ventricular rate of 40 bpm, wide QRS complexes (0.16 seconds), and no P
waves. The patient is hypotensive and confused. Which of the following is the most
appropriate initial treatment?
A. Atropine 0.5 mg IV push
B. Transcutaneous pacing
C. Isoproterenol infusion
D. Implantable cardioverter-defibrillator placement
Answer: B
7. A rhythm strip shows a regular rhythm at 75 bpm with a PR interval of 0.24 seconds and
a QRS duration of 0.10 seconds. Which of the following conduction abnormalities is
present?
A. First-degree AV block
B. Mobitz type I second-degree AV block
C. Mobitz type II second-degree AV block
D. Left anterior fascicular block
Answer: A
8. A patient with a history of heart failure with reduced ejection fraction is on digoxin
therapy. The rhythm strip shows a regular atrial rate of 70 bpm, but the ventricular rate is
35 bpm and irregular, with grouped beating. The PR interval progressively lengthens
before a dropped QRS. Which of the following is the most likely cause?
A. Digoxin toxicity causing enhanced automaticity
B. Digoxin toxicity causing increased vagal tone and AV nodal blockade
C. Digoxin toxicity causing accelerated junctional rhythm
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, D. Digoxin toxicity causing ventricular bigeminy
Answer: B
9. A patient presents with palpitations. An ECG shows a narrow-complex tachycardia at
150 bpm with P waves that are inverted in leads II, III, and aVF. The P waves precede each
QRS with a PR interval of 0.12 seconds. Which of the following is the most likely origin of
the tachycardia?
A. Sinoatrial node
B. Atrioventricular node
C. Low atrial focus near the coronary sinus
D. Accessory pathway (Wolff-Parkinson-White syndrome)
Answer: C
10. A patient with a history of myocardial infarction has an ECG showing a wide QRS
(0.14 seconds) with an rSR' pattern in lead V1 and a wide, deep S wave in lead V6. The axis
is normal. Which of the following conduction abnormalities is most likely?
A. Left bundle branch block
B. Right bundle branch block
C. Left anterior fascicular block
D. Nonspecific intraventricular conduction delay
Answer: B
11. A patient presents with a wide QRS tachycardia at a rate of 180 bpm. The rhythm is
irregular, and you note that some QRS complexes appear narrower than others. Which of
the following mechanisms best explains this phenomenon?
A. Atrial fibrillation with pre-excitation via an accessory pathway, causing variable conduction to the
ventricles.
B. Ventricular tachycardia with intermittent fusion beats due to competing sinus node activity.
C. Supraventricular tachycardia with aberrancy that varies with the preceding R-R interval (Ashman
phenomenon).
D. Atrial flutter with variable block and intermittent bundle branch block due to rate-related aberrancy.
Answer: A
12. A patient's rhythm strip shows a regular narrow QRS tachycardia at 150 bpm with
visible P waves that are inverted in leads II, III, and aVF. The RP interval is longer than
the PR interval. Which of the following is the most likely diagnosis?
A. Atrioventricular nodal reentrant tachycardia (AVNRT), typical (slow-fast) form.
B. Atrioventricular reentrant tachycardia (AVRT) using a concealed accessory pathway.
C. Atrial tachycardia originating from the low right atrium near the coronary sinus.
D. Junctional ectopic tachycardia with retrograde atrial activation.
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