RELIAS DYSRHYTHMIA BASIC A TEST - 2025/2026 -
COMPLETE QUESTIONS AND CORRECT ANSWERS WITH
EXPLANATIONS GRADED A+. - 150 Questions and Answers
Already Graded A+ Premium Exam Tested And Verified
Subject Area Cardiac Dysrhythmia Interpretation and Management
Description This examination assesses advanced competency in interpreting cardiac
dysrhythmias, identifying underlying electrophysiological mechanisms, and
selecting appropriate evidence-based interventions. Content includes sinus node
disorders, atrial and ventricular arrhythmias, conduction abnormalities, and
advanced ECG concepts such as axis deviation, chamber enlargement, and
ischemia localization. The exam reflects the latest AHA/ACC/HRS guidelines and
2025 updates.
Expected Grade A+
Total Questions 150
Duration 3 hours
Learning Outcomes 1. Accurately interpret complex ECG tracings and distinguish between subtle
dysrhythmia variants.
2. Apply electrophysiological principles to explain the mechanisms of
arrhythmogenesis.
3. Integrate clinical context to prioritize interventions and anticipate
complications.
4. Evaluate the impact of electrolyte imbalances, ischemia, and drug effects on
cardiac conduction.
Accreditation This exam meets the rigorous standards of Ivy League and R1 research
universities, consistent with USMLE Step 2 CK and advanced nursing
certification (e.g., AACN, CCNE) guidelines.
Page 1
,1. A 72-year-old patient with a history of hypertension and heart failure presents
with an irregularly irregular rhythm. The ECG shows no discernible P waves, an
irregular ventricular rate of 110 bpm, and narrow QRS complexes. Which of the
following electrophysiological mechanisms is most likely responsible for this
rhythm?
Answer: Multiple reentrant wavelets propagating through atrial tissue with
fibrillatory conduction
The description is classic for atrial fibrillation, which is maintained by multiple
reentrant wavelets (random reentry) and fibrillatory conduction. Option A describes
sinus arrhythmia with exit block; option C describes atrial flutter (single reentrant
circuit); option D could cause atrial tachycardia but not the chaotic pattern of
fibrillation.
2. A 55-year-old patient with coronary artery disease experiences a wide-complex
tachycardia at 180 bpm. The QRS morphology is consistent with left bundle branch
block (LBBB) and there is no evidence of atrioventricular dissociation. Which of the
following findings would most strongly support a diagnosis of ventricular
tachycardia rather than supraventricular tachycardia with aberrancy?
Answer: RS interval > 100 ms in any precordial lead
An RS interval > 100 ms in any precordial lead is a criterion for ventricular
tachycardia (Brugada algorithm). Option A suggests AV association, favoring SVT.
Option B is typical for LBBB aberrancy. Option D can occur in LBBB and is not
specific. Ventricular tachycardia often shows a longer RS interval due to myocardial
activation via slower muscle-to-muscle conduction.
3. A patient with a serum potassium of 6.8 mEq/L and a serum calcium of 8.0 mg/dL
has an ECG showing tall, peaked T waves, loss of P waves, and a widened QRS
complex. Which of the following best explains the combined effect of these electrolyte
disturbances on the cardiac action potential?
Answer: Hyperkalemia decreases resting membrane potential, inactivating sodium
channels; hypocalcemia prolongs phase 2, further slowing conduction.
Hyperkalemia reduces the resting membrane potential (less negative), inactivating
sodium channels and slowing conduction (wide QRS, loss of P waves). Hypocalcemia
prolongs phase 2 (plateau) by decreasing calcium influx, which also slows conduction
and widens QRS. Tall, peaked T waves are due to accelerated repolarization from
hyperkalemia. Option A incorrectly describes hypocalcemia prolonging plateau; option
C oversimplifies; option D is incorrect.
Page 2
,4. A patient with an anterior ST-elevation myocardial infarction develops a rhythm
with a regular rate of 45 bpm, a PR interval of 0.20 seconds, and a QRS duration of
0.12 seconds with left anterior fascicular block morphology. Which of the following
conduction abnormalities is most likely present?
Answer: First-degree AV block with bifascicular block (right bundle branch block
and left anterior fascicular block)
First-degree AV block (PR > 0.20 s) plus left anterior fascicular block (left axis
deviation, qR in I, rS in II/III) plus right bundle branch block (wide QRS) constitutes
bifascicular block. The QRS duration of 0.12 s suggests incomplete RBBB or a
combination of fascicular block with some delay. Option B is incorrect because Mobitz
I has progressive PR prolongation; option C suggests trifascicular block but there is no
evidence of posterior fascicular block; option D would show complete heart block with
an escape rhythm, not first-degree AV block.
5. A 60-year-old patient with chronic atrial fibrillation and a ventricular rate of 130
bpm is started on digoxin. After 48 hours, the rhythm converts to atrial tachycardia
with 2:1 AV block. Which of the following best explains this rhythm change?
Answer: Digitalis toxicity causing increased atrial automaticity and depressed AV
nodal conduction
Digitalis toxicity can cause atrial tachycardia with block (PAT with block). Digoxin
increases intracellular calcium, leading to delayed afterdepolarizations (increased
automaticity) and also depresses AV nodal conduction (causing block). Option A is
incorrect because digoxin does not enhance AV conduction; option C is unlikely as
conversion from AF to sinus is not typical with digoxin; option D is not specific.
6. An ECG from a patient with acute inferior STEMI shows a regular wide-complex
tachycardia at 170 bpm. The QRS morphology is a right bundle branch block
pattern with left anterior fascicular block. Which of the following is the most likely
diagnosis?
Answer: Ventricular tachycardia originating from the inferolateral left ventricle
near the posterior fascicle
In the setting of acute infarction, a wide-complex tachycardia with RBBB and LAHB
morphology is most likely ventricular tachycardia. The pattern suggests an exit site
near the posterior fascicle (since the initial activation is via the posterior fascicle,
causing RBBB+LAHB). Option A is less likely because pre-existing bifascicular block
would cause a wide QRS but not necessarily tachycardia; option C would show atrial
activity; option D is a slow rhythm (40-100 bpm).
Page 3
, 7. A 45-year-old patient with no structural heart disease experiences palpitations and
lightheadedness. ECG shows a narrow-complex tachycardia at 190 bpm with a P
wave visible after the QRS in lead II, and the RP interval is longer than the PR
interval. Which of the following mechanisms is most likely responsible?
Answer: Orthodromic atrioventricular reentrant tachycardia using a concealed
accessory pathway
The long RP tachycardia (RP > PR) with a P wave after the QRS is characteristic of
orthodromic AVRT using a concealed accessory pathway (which conducts only
retrograde). In typical AVNRT (slow-fast), the P wave is buried in the QRS or appears
just after (short RP). Atrial tachycardia often has a P wave before the QRS. Junctional
tachycardia is usually slower and irregular.
8. A patient with dilated cardiomyopathy and a left ventricular ejection fraction of
25% has an ECG showing sinus rhythm with a PR interval of 0.24 seconds and a
QRS duration of 0.16 seconds with a left bundle branch block pattern. Which of the
following is the most appropriate next step in management according to current
guidelines?
Answer: Refer for cardiac resynchronization therapy with defibrillator capability
Current guidelines (ACC/AHA/HRS 2024) recommend CRT-D for patients with LVEF
35%, LBBB, and QRS duration 150 ms, regardless of PR interval. First-degree AV
block alone is not an indication for pacing. Amiodarone is not indicated for conduction
disease. An EP study may be considered if there is suspicion of infra-Hisian block, but
in this clinical scenario, CRT-D is first-line.
9. A 68-year-old patient with hypertensive heart disease has an ECG that shows a
QRS axis of -45°, a QRS duration of 0.10 seconds, and an R wave amplitude in lead
aVL of 1.5 mV. Which of the following best describes these findings?
Answer: Left anterior fascicular block with left ventricular hypertrophy (voltage
criteria)
Left anterior fascicular block (LAFB) causes left axis deviation ( -45°) with a QRS
duration < 0.12 s. The R wave in aVL 1.1 mV is a voltage criterion for left ventricular
hypertrophy (LVH). Option B is less likely because inferior MI would show Q waves in
II, III, aVF. Option C is not a normal variant. Option D requires QRS 0.12 s for
incomplete LBBB.
Page 4
COMPLETE QUESTIONS AND CORRECT ANSWERS WITH
EXPLANATIONS GRADED A+. - 150 Questions and Answers
Already Graded A+ Premium Exam Tested And Verified
Subject Area Cardiac Dysrhythmia Interpretation and Management
Description This examination assesses advanced competency in interpreting cardiac
dysrhythmias, identifying underlying electrophysiological mechanisms, and
selecting appropriate evidence-based interventions. Content includes sinus node
disorders, atrial and ventricular arrhythmias, conduction abnormalities, and
advanced ECG concepts such as axis deviation, chamber enlargement, and
ischemia localization. The exam reflects the latest AHA/ACC/HRS guidelines and
2025 updates.
Expected Grade A+
Total Questions 150
Duration 3 hours
Learning Outcomes 1. Accurately interpret complex ECG tracings and distinguish between subtle
dysrhythmia variants.
2. Apply electrophysiological principles to explain the mechanisms of
arrhythmogenesis.
3. Integrate clinical context to prioritize interventions and anticipate
complications.
4. Evaluate the impact of electrolyte imbalances, ischemia, and drug effects on
cardiac conduction.
Accreditation This exam meets the rigorous standards of Ivy League and R1 research
universities, consistent with USMLE Step 2 CK and advanced nursing
certification (e.g., AACN, CCNE) guidelines.
Page 1
,1. A 72-year-old patient with a history of hypertension and heart failure presents
with an irregularly irregular rhythm. The ECG shows no discernible P waves, an
irregular ventricular rate of 110 bpm, and narrow QRS complexes. Which of the
following electrophysiological mechanisms is most likely responsible for this
rhythm?
Answer: Multiple reentrant wavelets propagating through atrial tissue with
fibrillatory conduction
The description is classic for atrial fibrillation, which is maintained by multiple
reentrant wavelets (random reentry) and fibrillatory conduction. Option A describes
sinus arrhythmia with exit block; option C describes atrial flutter (single reentrant
circuit); option D could cause atrial tachycardia but not the chaotic pattern of
fibrillation.
2. A 55-year-old patient with coronary artery disease experiences a wide-complex
tachycardia at 180 bpm. The QRS morphology is consistent with left bundle branch
block (LBBB) and there is no evidence of atrioventricular dissociation. Which of the
following findings would most strongly support a diagnosis of ventricular
tachycardia rather than supraventricular tachycardia with aberrancy?
Answer: RS interval > 100 ms in any precordial lead
An RS interval > 100 ms in any precordial lead is a criterion for ventricular
tachycardia (Brugada algorithm). Option A suggests AV association, favoring SVT.
Option B is typical for LBBB aberrancy. Option D can occur in LBBB and is not
specific. Ventricular tachycardia often shows a longer RS interval due to myocardial
activation via slower muscle-to-muscle conduction.
3. A patient with a serum potassium of 6.8 mEq/L and a serum calcium of 8.0 mg/dL
has an ECG showing tall, peaked T waves, loss of P waves, and a widened QRS
complex. Which of the following best explains the combined effect of these electrolyte
disturbances on the cardiac action potential?
Answer: Hyperkalemia decreases resting membrane potential, inactivating sodium
channels; hypocalcemia prolongs phase 2, further slowing conduction.
Hyperkalemia reduces the resting membrane potential (less negative), inactivating
sodium channels and slowing conduction (wide QRS, loss of P waves). Hypocalcemia
prolongs phase 2 (plateau) by decreasing calcium influx, which also slows conduction
and widens QRS. Tall, peaked T waves are due to accelerated repolarization from
hyperkalemia. Option A incorrectly describes hypocalcemia prolonging plateau; option
C oversimplifies; option D is incorrect.
Page 2
,4. A patient with an anterior ST-elevation myocardial infarction develops a rhythm
with a regular rate of 45 bpm, a PR interval of 0.20 seconds, and a QRS duration of
0.12 seconds with left anterior fascicular block morphology. Which of the following
conduction abnormalities is most likely present?
Answer: First-degree AV block with bifascicular block (right bundle branch block
and left anterior fascicular block)
First-degree AV block (PR > 0.20 s) plus left anterior fascicular block (left axis
deviation, qR in I, rS in II/III) plus right bundle branch block (wide QRS) constitutes
bifascicular block. The QRS duration of 0.12 s suggests incomplete RBBB or a
combination of fascicular block with some delay. Option B is incorrect because Mobitz
I has progressive PR prolongation; option C suggests trifascicular block but there is no
evidence of posterior fascicular block; option D would show complete heart block with
an escape rhythm, not first-degree AV block.
5. A 60-year-old patient with chronic atrial fibrillation and a ventricular rate of 130
bpm is started on digoxin. After 48 hours, the rhythm converts to atrial tachycardia
with 2:1 AV block. Which of the following best explains this rhythm change?
Answer: Digitalis toxicity causing increased atrial automaticity and depressed AV
nodal conduction
Digitalis toxicity can cause atrial tachycardia with block (PAT with block). Digoxin
increases intracellular calcium, leading to delayed afterdepolarizations (increased
automaticity) and also depresses AV nodal conduction (causing block). Option A is
incorrect because digoxin does not enhance AV conduction; option C is unlikely as
conversion from AF to sinus is not typical with digoxin; option D is not specific.
6. An ECG from a patient with acute inferior STEMI shows a regular wide-complex
tachycardia at 170 bpm. The QRS morphology is a right bundle branch block
pattern with left anterior fascicular block. Which of the following is the most likely
diagnosis?
Answer: Ventricular tachycardia originating from the inferolateral left ventricle
near the posterior fascicle
In the setting of acute infarction, a wide-complex tachycardia with RBBB and LAHB
morphology is most likely ventricular tachycardia. The pattern suggests an exit site
near the posterior fascicle (since the initial activation is via the posterior fascicle,
causing RBBB+LAHB). Option A is less likely because pre-existing bifascicular block
would cause a wide QRS but not necessarily tachycardia; option C would show atrial
activity; option D is a slow rhythm (40-100 bpm).
Page 3
, 7. A 45-year-old patient with no structural heart disease experiences palpitations and
lightheadedness. ECG shows a narrow-complex tachycardia at 190 bpm with a P
wave visible after the QRS in lead II, and the RP interval is longer than the PR
interval. Which of the following mechanisms is most likely responsible?
Answer: Orthodromic atrioventricular reentrant tachycardia using a concealed
accessory pathway
The long RP tachycardia (RP > PR) with a P wave after the QRS is characteristic of
orthodromic AVRT using a concealed accessory pathway (which conducts only
retrograde). In typical AVNRT (slow-fast), the P wave is buried in the QRS or appears
just after (short RP). Atrial tachycardia often has a P wave before the QRS. Junctional
tachycardia is usually slower and irregular.
8. A patient with dilated cardiomyopathy and a left ventricular ejection fraction of
25% has an ECG showing sinus rhythm with a PR interval of 0.24 seconds and a
QRS duration of 0.16 seconds with a left bundle branch block pattern. Which of the
following is the most appropriate next step in management according to current
guidelines?
Answer: Refer for cardiac resynchronization therapy with defibrillator capability
Current guidelines (ACC/AHA/HRS 2024) recommend CRT-D for patients with LVEF
35%, LBBB, and QRS duration 150 ms, regardless of PR interval. First-degree AV
block alone is not an indication for pacing. Amiodarone is not indicated for conduction
disease. An EP study may be considered if there is suspicion of infra-Hisian block, but
in this clinical scenario, CRT-D is first-line.
9. A 68-year-old patient with hypertensive heart disease has an ECG that shows a
QRS axis of -45°, a QRS duration of 0.10 seconds, and an R wave amplitude in lead
aVL of 1.5 mV. Which of the following best describes these findings?
Answer: Left anterior fascicular block with left ventricular hypertrophy (voltage
criteria)
Left anterior fascicular block (LAFB) causes left axis deviation ( -45°) with a QRS
duration < 0.12 s. The R wave in aVL 1.1 mV is a voltage criterion for left ventricular
hypertrophy (LVH). Option B is less likely because inferior MI would show Q waves in
II, III, aVF. Option C is not a normal variant. Option D requires QRS 0.12 s for
incomplete LBBB.
Page 4
