DYSRHYTHMIA STUFF (AHN 447)
COMPREHENSIVE EXAM PRACTICE & ACTUAL
STUDY GUIDE — 2026/2027 UPDATE EXAM
QUESTIONS 100% WITH CORRECT ANSWERS AND
RATIOALES
A patient’s ECG shows a regular rhythm with a ventricular rate of 78 beats/min,
a P wave before every QRS complex, a consistent PR interval, and narrow QRS
complexes. Which rhythm is most consistent with these findings?
• A. Atrial fibrillation
• B. Sinus tachycardia
• C. Normal sinus rhythm
• D. Junctional rhythm
Answer: C. Normal sinus rhythm
Rationale: Normal sinus rhythm originates from the sinoatrial node, the
heart’s natural pacemaker. It is characterized by a regular rhythm, a rate generally
between 60 and 100 beats/min in adults, a consistent P wave preceding each QRS
complex, a consistent PR interval, and a narrow QRS complex. Recognizing these
features establishes a baseline for identifying abnormal rhythms and is essential
when interpreting more complex dysrhythmias.
A patient suddenly develops a heart rate of 168 beats/min. The ECG
demonstrates a regular narrow-complex rhythm with identical-appearing QRS
complexes occurring at very short intervals. Which rhythm should the nurse
suspect?
• A. Supraventricular tachycardia
• B. Sinus bradycardia
Page 1 of 52
, • C. Ventricular fibrillation
• D. First-degree AV block
Answer: A. Supraventricular tachycardia
Rationale: Supraventricular tachycardia is characterized by a rapid rhythm
originating above the ventricles, often involving the atria or AV junction. The
ventricular rate can become extremely rapid, commonly exceeding 150 beats/min,
while the QRS complexes usually remain narrow because ventricular conduction
still occurs through the normal His-Purkinje system. The abrupt onset and
termination of a regular narrow-complex tachycardia are particularly important
clinical clues.
Which ECG component represents the time required for an electrical impulse to
travel from the atria through the AV node and conduction system to the
ventricles?
• A. QRS interval
• B. PR interval
• C. ST segment
• D. QT interval
Answer: B. PR interval
Rationale: The PR interval measures the time from the beginning of atrial
depolarization, represented by the start of the P wave, to the beginning of
ventricular depolarization, represented by the start of the QRS complex. It reflects
conduction through the atria, AV node, and His-Purkinje system. Changes in the
PR interval can provide important information about conduction abnormalities,
including different degrees of atrioventricular block.
A patient’s ECG demonstrates an irregularly irregular rhythm with no clearly
identifiable P waves and a variable ventricular response. Which dysrhythmia is
most likely present?
• A. Atrial flutter
Page 2 of 52
, • B. Sinus arrhythmia
• C. Ventricular tachycardia
• D. Atrial fibrillation
Answer: D. Atrial fibrillation
Rationale: Atrial fibrillation is characterized by chaotic atrial electrical activity,
resulting in the absence of organized P waves and an irregularly irregular
ventricular rhythm. The atria do not contract in a coordinated manner, which can
reduce effective atrial contribution to ventricular filling. Because blood can
become relatively stagnant within the atria, particularly the left atrial appendage,
atrial fibrillation is clinically important because of its association with
thromboembolic stroke.
A patient has a heart rate of 48 beats/min with a regular rhythm. Each QRS
complex is preceded by a normal P wave, and the PR interval is consistent.
Which rhythm is present?
• A. Sinus bradycardia
• B. Complete heart block
• C. Atrial fibrillation
• D. Ventricular tachycardia
Answer: A. Sinus bradycardia
Rationale: Sinus bradycardia originates from the sinoatrial node but occurs at
a rate below the normal adult resting range, generally less than 60 beats/min. The
presence of normal P waves before each QRS and a consistent PR interval
indicates that the electrical impulse is following the normal conduction pathway.
Sinus bradycardia can be physiologic in well-conditioned individuals but may also
occur with medications, increased vagal tone, hypothermia, or conduction-system
disease.
Which ECG finding is most characteristic of atrial flutter?
• A. Completely absent electrical activity
Page 3 of 52
, • B. Wide chaotic QRS complexes
• C. Repeating sawtooth atrial waves
• D. Prolonged QT interval only
Answer: C. Repeating sawtooth atrial waves
Rationale: Atrial flutter results from a rapid organized atrial reentry circuit,
commonly producing atrial rates around 250 to 350 beats/min. The ECG may show
characteristic repetitive flutter waves, often described as having a sawtooth
appearance, particularly in the inferior leads. The AV node may conduct only some
of these atrial impulses to the ventricles, producing conduction ratios such as 2:1,
3:1, or 4:1.
A patient with a rapid regular rhythm has wide QRS complexes measuring 0.14
seconds. The nurse should recognize this finding as which type of rhythm
characteristic?
• A. Narrow-complex rhythm
• B. Wide-complex rhythm
• C. Normal atrial conduction
• D. Sinus rhythm
Answer: B. Wide-complex rhythm
Rationale: A QRS duration of 0.12 seconds or greater is considered wide. A
wide QRS indicates that ventricular depolarization is not occurring through the
normal rapid His-Purkinje pathway or that ventricular conduction is otherwise
delayed. In the setting of tachycardia, a wide-complex rhythm requires careful
assessment because ventricular tachycardia is an important and potentially life-
threatening cause.
Which dysrhythmia is characterized by a chaotic electrical pattern with no
organized ventricular depolarization and requires immediate defibrillation when
appropriate?
• A. Sinus bradycardia
Page 4 of 52
COMPREHENSIVE EXAM PRACTICE & ACTUAL
STUDY GUIDE — 2026/2027 UPDATE EXAM
QUESTIONS 100% WITH CORRECT ANSWERS AND
RATIOALES
A patient’s ECG shows a regular rhythm with a ventricular rate of 78 beats/min,
a P wave before every QRS complex, a consistent PR interval, and narrow QRS
complexes. Which rhythm is most consistent with these findings?
• A. Atrial fibrillation
• B. Sinus tachycardia
• C. Normal sinus rhythm
• D. Junctional rhythm
Answer: C. Normal sinus rhythm
Rationale: Normal sinus rhythm originates from the sinoatrial node, the
heart’s natural pacemaker. It is characterized by a regular rhythm, a rate generally
between 60 and 100 beats/min in adults, a consistent P wave preceding each QRS
complex, a consistent PR interval, and a narrow QRS complex. Recognizing these
features establishes a baseline for identifying abnormal rhythms and is essential
when interpreting more complex dysrhythmias.
A patient suddenly develops a heart rate of 168 beats/min. The ECG
demonstrates a regular narrow-complex rhythm with identical-appearing QRS
complexes occurring at very short intervals. Which rhythm should the nurse
suspect?
• A. Supraventricular tachycardia
• B. Sinus bradycardia
Page 1 of 52
, • C. Ventricular fibrillation
• D. First-degree AV block
Answer: A. Supraventricular tachycardia
Rationale: Supraventricular tachycardia is characterized by a rapid rhythm
originating above the ventricles, often involving the atria or AV junction. The
ventricular rate can become extremely rapid, commonly exceeding 150 beats/min,
while the QRS complexes usually remain narrow because ventricular conduction
still occurs through the normal His-Purkinje system. The abrupt onset and
termination of a regular narrow-complex tachycardia are particularly important
clinical clues.
Which ECG component represents the time required for an electrical impulse to
travel from the atria through the AV node and conduction system to the
ventricles?
• A. QRS interval
• B. PR interval
• C. ST segment
• D. QT interval
Answer: B. PR interval
Rationale: The PR interval measures the time from the beginning of atrial
depolarization, represented by the start of the P wave, to the beginning of
ventricular depolarization, represented by the start of the QRS complex. It reflects
conduction through the atria, AV node, and His-Purkinje system. Changes in the
PR interval can provide important information about conduction abnormalities,
including different degrees of atrioventricular block.
A patient’s ECG demonstrates an irregularly irregular rhythm with no clearly
identifiable P waves and a variable ventricular response. Which dysrhythmia is
most likely present?
• A. Atrial flutter
Page 2 of 52
, • B. Sinus arrhythmia
• C. Ventricular tachycardia
• D. Atrial fibrillation
Answer: D. Atrial fibrillation
Rationale: Atrial fibrillation is characterized by chaotic atrial electrical activity,
resulting in the absence of organized P waves and an irregularly irregular
ventricular rhythm. The atria do not contract in a coordinated manner, which can
reduce effective atrial contribution to ventricular filling. Because blood can
become relatively stagnant within the atria, particularly the left atrial appendage,
atrial fibrillation is clinically important because of its association with
thromboembolic stroke.
A patient has a heart rate of 48 beats/min with a regular rhythm. Each QRS
complex is preceded by a normal P wave, and the PR interval is consistent.
Which rhythm is present?
• A. Sinus bradycardia
• B. Complete heart block
• C. Atrial fibrillation
• D. Ventricular tachycardia
Answer: A. Sinus bradycardia
Rationale: Sinus bradycardia originates from the sinoatrial node but occurs at
a rate below the normal adult resting range, generally less than 60 beats/min. The
presence of normal P waves before each QRS and a consistent PR interval
indicates that the electrical impulse is following the normal conduction pathway.
Sinus bradycardia can be physiologic in well-conditioned individuals but may also
occur with medications, increased vagal tone, hypothermia, or conduction-system
disease.
Which ECG finding is most characteristic of atrial flutter?
• A. Completely absent electrical activity
Page 3 of 52
, • B. Wide chaotic QRS complexes
• C. Repeating sawtooth atrial waves
• D. Prolonged QT interval only
Answer: C. Repeating sawtooth atrial waves
Rationale: Atrial flutter results from a rapid organized atrial reentry circuit,
commonly producing atrial rates around 250 to 350 beats/min. The ECG may show
characteristic repetitive flutter waves, often described as having a sawtooth
appearance, particularly in the inferior leads. The AV node may conduct only some
of these atrial impulses to the ventricles, producing conduction ratios such as 2:1,
3:1, or 4:1.
A patient with a rapid regular rhythm has wide QRS complexes measuring 0.14
seconds. The nurse should recognize this finding as which type of rhythm
characteristic?
• A. Narrow-complex rhythm
• B. Wide-complex rhythm
• C. Normal atrial conduction
• D. Sinus rhythm
Answer: B. Wide-complex rhythm
Rationale: A QRS duration of 0.12 seconds or greater is considered wide. A
wide QRS indicates that ventricular depolarization is not occurring through the
normal rapid His-Purkinje pathway or that ventricular conduction is otherwise
delayed. In the setting of tachycardia, a wide-complex rhythm requires careful
assessment because ventricular tachycardia is an important and potentially life-
threatening cause.
Which dysrhythmia is characterized by a chaotic electrical pattern with no
organized ventricular depolarization and requires immediate defibrillation when
appropriate?
• A. Sinus bradycardia
Page 4 of 52
