RELIAS DYSRHYTHMIA BASIC A TEST 2026/2027 |
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Section 1: Normal Sinus Rhythm & Sinus Arrhythmias (Questions 1-10)
Q1. An ECG rhythm strip shows a regular rhythm with a rate of 72 bpm. There is an
upright P wave before each QRS complex in lead II. The PR interval measures 0.16
seconds, and the QRS duration is 0.08 seconds. Which rhythm is present?
A. Sinus bradycardia
B. Normal sinus rhythm
C. First-degree AV block
D. Junctional rhythm
B. Normal sinus rhythm [CORRECT]
Rationale: Normal sinus rhythm requires a regular rhythm, rate 60–100 bpm, an
upright P wave before each QRS in lead II, a PR interval of 0.12–0.20 seconds, and a
QRS duration <0.12 seconds. This strip meets all criteria. Sinus bradycardia would
require a rate <60 bpm, first-degree AV block requires PR >0.20 seconds, and
junctional rhythm would not have upright P waves preceding each QRS.
Correct Answer: B
Q2. A patient has a regular rhythm with a rate of 52 bpm. P waves are upright and
precede each QRS complex. The PR interval is 0.18 seconds. The patient is
asymptomatic with normal blood pressure. Which management is most appropriate?
A. Immediate transcutaneous pacing
B. Atropine 0.5 mg IV push
C. Observation; no treatment required
D. Epinephrine infusion at 2 mcg/min
C. Observation; no treatment required [CORRECT]
,Rationale: Asymptomatic sinus bradycardia does not require treatment regardless of
rate. Intervention is indicated only when bradycardia causes hypotension, altered
mental status, signs of shock, ischemic chest discomfort, acute heart failure, or
syncope. Atropine, pacing, and epinephrine are reserved for symptomatic
bradycardia per ACLS guidelines.
Correct Answer: C
Q3. Which of the following causes of sinus bradycardia is specifically associated with
inferior wall myocardial infarction due to right coronary artery occlusion?
A. Increased intracranial pressure
B. Hypothyroidism
C. Inferior MI with AV nodal ischemia
D. Hypothermia
C. Inferior MI with AV nodal ischemia [CORRECT]
Rationale: The right coronary artery supplies the sinoatrial node in most individuals;
inferior MI caused by RCA occlusion can produce sinus bradycardia through SA node
ischemia or increased vagal tone. While increased ICP, hypothyroidism, and
hypothermia also cause bradycardia, they are not specifically linked to RCA occlusion.
Correct Answer: C
Q4. A patient with symptomatic sinus bradycardia (heart rate 38 bpm) and
hypotension (BP 78/52) receives atropine per ACLS protocol. What is the correct
initial dose and maximum cumulative dose?
A. 0.3 mg IV every 5 minutes; maximum 2 mg
B. 0.5 mg IV every 3–5 minutes; maximum 3 mg
C. 1 mg IV every 3 minutes; maximum 5 mg
D. 2 mg IV single dose; maximum 2 mg
B. 0.5 mg IV every 3–5 minutes; maximum 3 mg [CORRECT]
,Rationale: ACLS guidelines recommend atropine 0.5 mg IV every 3–5 minutes for
symptomatic bradycardia, with a maximum total dose of 3 mg. Doses below 0.5 mg
may paradoxically worsen bradycardia due to central vagal stimulation. If atropine is
ineffective, transcutaneous pacing or vasopressor infusions are indicated.
Correct Answer: B
Q5. A postoperative patient has sinus tachycardia at 128 bpm. She is febrile at 38.5°C,
has a urine output of 15 mL/hr, and complains of incisional pain. Which intervention
is most appropriate?
A. Administer metoprolol 5 mg IV immediately
B. Perform carotid massage
C. Treat underlying causes: fever, hypovolemia, and pain
D. Administer adenosine 6 mg rapid IV push
C. Treat underlying causes: fever, hypovolemia, and pain [CORRECT]
Rationale: Sinus tachycardia is a physiological response to underlying stressors such
as fever (approximately ↑10 bpm per 1°C), hypovolemia, pain, hypoxia, or anemia.
The appropriate management is to identify and treat the cause rather than the rate.
Beta-blockers are reserved for rate control in specific contexts such as myocardial
ischemia or thyrotoxicosis.
Correct Answer: C
Q6. Sinus arrhythmia is characterized by which of the following ECG findings?
A. Absent P waves with irregular ventricular response
B. Variation in P-P interval >0.12 seconds, with rate increasing during inspiration and
decreasing during expiration
C. Progressive prolongation of the PR interval until a QRS is dropped
D. Regular rhythm with rate >100 bpm and upright P waves
, B. Variation in P-P interval >0.12 seconds, with rate increasing during inspiration and
decreasing during expiration [CORRECT]
Rationale: Sinus arrhythmia is a normal variant, particularly in young healthy
individuals, characterized by a phasic variation in the P-P interval exceeding 0.12
seconds corresponding with the respiratory cycle. It is benign, usually asymptomatic,
and requires no treatment. Absent P waves suggest a junctional or atrial fibrillation
mechanism.
Correct Answer: B
Q7. An ECG strip demonstrates a pause of 2.4 seconds during which no P wave or
QRS complex occurs. The pause is not a multiple of the baseline P-P interval. This
finding is most consistent with?
A. Sinus exit block, second-degree Type I
B. Sinus pause (sinus arrest)
C. Third-degree AV block
D. Sinus exit block, second-degree Type II
B. Sinus pause (sinus arrest) [CORRECT]
Rationale: Sinus pause (arrest) occurs when the SA node fails to fire, producing a
pause that is not a multiple of the normal P-P interval. In contrast, sinus exit block
occurs when the SA node fires but the impulse is blocked from exiting into the atria,
producing a pause that is a multiple of the normal P-P interval (e.g., exactly 2× or 3×
the baseline cycle length).
Correct Answer: B
Q8. Sick sinus syndrome (SSS) is characterized by which constellation of findings?
A. Persistent atrial fibrillation with rapid ventricular response
B. Severe sinus bradycardia, sinus pauses >3 seconds, sinus exit block, and
alternating bradycardia with tachycardia
Review Solution Guide | A+ Graded 100% Verified |
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Section 1: Normal Sinus Rhythm & Sinus Arrhythmias (Questions 1-10)
Q1. An ECG rhythm strip shows a regular rhythm with a rate of 72 bpm. There is an
upright P wave before each QRS complex in lead II. The PR interval measures 0.16
seconds, and the QRS duration is 0.08 seconds. Which rhythm is present?
A. Sinus bradycardia
B. Normal sinus rhythm
C. First-degree AV block
D. Junctional rhythm
B. Normal sinus rhythm [CORRECT]
Rationale: Normal sinus rhythm requires a regular rhythm, rate 60–100 bpm, an
upright P wave before each QRS in lead II, a PR interval of 0.12–0.20 seconds, and a
QRS duration <0.12 seconds. This strip meets all criteria. Sinus bradycardia would
require a rate <60 bpm, first-degree AV block requires PR >0.20 seconds, and
junctional rhythm would not have upright P waves preceding each QRS.
Correct Answer: B
Q2. A patient has a regular rhythm with a rate of 52 bpm. P waves are upright and
precede each QRS complex. The PR interval is 0.18 seconds. The patient is
asymptomatic with normal blood pressure. Which management is most appropriate?
A. Immediate transcutaneous pacing
B. Atropine 0.5 mg IV push
C. Observation; no treatment required
D. Epinephrine infusion at 2 mcg/min
C. Observation; no treatment required [CORRECT]
,Rationale: Asymptomatic sinus bradycardia does not require treatment regardless of
rate. Intervention is indicated only when bradycardia causes hypotension, altered
mental status, signs of shock, ischemic chest discomfort, acute heart failure, or
syncope. Atropine, pacing, and epinephrine are reserved for symptomatic
bradycardia per ACLS guidelines.
Correct Answer: C
Q3. Which of the following causes of sinus bradycardia is specifically associated with
inferior wall myocardial infarction due to right coronary artery occlusion?
A. Increased intracranial pressure
B. Hypothyroidism
C. Inferior MI with AV nodal ischemia
D. Hypothermia
C. Inferior MI with AV nodal ischemia [CORRECT]
Rationale: The right coronary artery supplies the sinoatrial node in most individuals;
inferior MI caused by RCA occlusion can produce sinus bradycardia through SA node
ischemia or increased vagal tone. While increased ICP, hypothyroidism, and
hypothermia also cause bradycardia, they are not specifically linked to RCA occlusion.
Correct Answer: C
Q4. A patient with symptomatic sinus bradycardia (heart rate 38 bpm) and
hypotension (BP 78/52) receives atropine per ACLS protocol. What is the correct
initial dose and maximum cumulative dose?
A. 0.3 mg IV every 5 minutes; maximum 2 mg
B. 0.5 mg IV every 3–5 minutes; maximum 3 mg
C. 1 mg IV every 3 minutes; maximum 5 mg
D. 2 mg IV single dose; maximum 2 mg
B. 0.5 mg IV every 3–5 minutes; maximum 3 mg [CORRECT]
,Rationale: ACLS guidelines recommend atropine 0.5 mg IV every 3–5 minutes for
symptomatic bradycardia, with a maximum total dose of 3 mg. Doses below 0.5 mg
may paradoxically worsen bradycardia due to central vagal stimulation. If atropine is
ineffective, transcutaneous pacing or vasopressor infusions are indicated.
Correct Answer: B
Q5. A postoperative patient has sinus tachycardia at 128 bpm. She is febrile at 38.5°C,
has a urine output of 15 mL/hr, and complains of incisional pain. Which intervention
is most appropriate?
A. Administer metoprolol 5 mg IV immediately
B. Perform carotid massage
C. Treat underlying causes: fever, hypovolemia, and pain
D. Administer adenosine 6 mg rapid IV push
C. Treat underlying causes: fever, hypovolemia, and pain [CORRECT]
Rationale: Sinus tachycardia is a physiological response to underlying stressors such
as fever (approximately ↑10 bpm per 1°C), hypovolemia, pain, hypoxia, or anemia.
The appropriate management is to identify and treat the cause rather than the rate.
Beta-blockers are reserved for rate control in specific contexts such as myocardial
ischemia or thyrotoxicosis.
Correct Answer: C
Q6. Sinus arrhythmia is characterized by which of the following ECG findings?
A. Absent P waves with irregular ventricular response
B. Variation in P-P interval >0.12 seconds, with rate increasing during inspiration and
decreasing during expiration
C. Progressive prolongation of the PR interval until a QRS is dropped
D. Regular rhythm with rate >100 bpm and upright P waves
, B. Variation in P-P interval >0.12 seconds, with rate increasing during inspiration and
decreasing during expiration [CORRECT]
Rationale: Sinus arrhythmia is a normal variant, particularly in young healthy
individuals, characterized by a phasic variation in the P-P interval exceeding 0.12
seconds corresponding with the respiratory cycle. It is benign, usually asymptomatic,
and requires no treatment. Absent P waves suggest a junctional or atrial fibrillation
mechanism.
Correct Answer: B
Q7. An ECG strip demonstrates a pause of 2.4 seconds during which no P wave or
QRS complex occurs. The pause is not a multiple of the baseline P-P interval. This
finding is most consistent with?
A. Sinus exit block, second-degree Type I
B. Sinus pause (sinus arrest)
C. Third-degree AV block
D. Sinus exit block, second-degree Type II
B. Sinus pause (sinus arrest) [CORRECT]
Rationale: Sinus pause (arrest) occurs when the SA node fails to fire, producing a
pause that is not a multiple of the normal P-P interval. In contrast, sinus exit block
occurs when the SA node fires but the impulse is blocked from exiting into the atria,
producing a pause that is a multiple of the normal P-P interval (e.g., exactly 2× or 3×
the baseline cycle length).
Correct Answer: B
Q8. Sick sinus syndrome (SSS) is characterized by which constellation of findings?
A. Persistent atrial fibrillation with rapid ventricular response
B. Severe sinus bradycardia, sinus pauses >3 seconds, sinus exit block, and
alternating bradycardia with tachycardia
