1
IBHRE CCDS TEST FINAL EXAM 2026/2027 | Actual Exam 2
Versions A & B | Complete Accurate Questions with Detailed
Verified Answers | 100% Correct | Already Graded A+ | Pass
Guaranteed
[VERSION A - 60 QUESTIONS - ALREADY GRADED A+]
[A1: Cardiac Anatomy, Electrophysiology & Rhythm Analysis - Q1-15]
Q1. A 68-year-old patient presents with symptomatic bradycardia. An
electrophysiology study demonstrates that progressive prolongation of the A-H
interval occurs with atrial pacing at 500 ms cycle length before block distal to the His
bundle. This finding localizes the conduction delay to which structure?
A. Right bundle branch
B. Left anterior fascicle
C. AV node
D. Distal His-Purkinje system
C. AV node [CORRECT]
Rationale: The A-H interval represents conduction through the AV node; progressive
prolongation with atrial pacing is characteristic of AV nodal decremental conduction.
Distal His-Purkinje system block would manifest as sudden H-V prolongation or
block without preceding A-H prolongation. The other options represent infra-Hisian
conduction tissue.
Correct Answer: C
Q2. During an EP study, the earliest atrial activation during sinus rhythm is recorded
at the high right atrium. If the sinus node fails, which structure typically assumes
pacemaker dominance due to its fastest intrinsic automaticity?
A. AV node
B. Bundle of His
,2
C. Left atrial appendage
D. Ventricular myocardium
A. AV node [CORRECT]
Rationale: The AV node has the second-fastest intrinsic automaticity (40-60 bpm)
and serves as the primary escape pacemaker when sinus node function is lost.
Ventricular escape rhythms are slower (20-40 bpm), while the Bundle of His and left
atrial appendage do not serve as dominant escape pacemakers under normal
physiological hierarchy.
Correct Answer: A
Q3. A patient with a dual-chamber pacemaker is noted to have consistent 2:1
atrioventricular conduction during atrial pacing at 120 bpm. The native PR interval is
200 ms. Which anatomical structure most likely accounts for this fixed ratio block?
A. SA node exit block
B. AV node refractoriness
C. Right bundle branch block
D. Left posterior fascicular block
B. AV node refractoriness [CORRECT]
Rationale: Fixed 2:1 AV block during atrial pacing at rates between 100-150 bpm
typically results from AV nodal refractoriness, as the AV node has the longest
refractory period in the conduction system. Infra-Hisian block usually produces wider
QRS morphologies and often progresses to higher-grade block at lower rates.
Correct Answer: B
Q4. On a 12-lead ECG, a patient demonstrates a left bundle branch block pattern
with QRS duration of 148 ms. Which conduction fascicle is most likely blocked, and
what is the expected axis if the remaining fascicles are intact?
,3
A. Right bundle branch; right axis deviation
B. Left anterior fascicle; left axis deviation
C. Left posterior fascicle; right axis deviation
D. Left bundle branch; normal or right axis deviation
D. Left bundle branch; normal or right axis deviation [CORRECT]
Rationale: A left bundle branch block (LBBB) pattern with QRS ≥120 ms indicates
interruption of the left bundle branch main trunk or both fascicles. The remaining
right bundle branch conducts normally, producing typical LBBB morphology. Left axis
deviation suggests left anterior fascicular block superimposed on RBBB, not isolated
LBBB.
Correct Answer: D
Q5. A patient with atrial fibrillation undergoes electrophysiological mapping. The
arrhythmia is found to originate from muscular sleeves extending from the left
atrium into which structure, representing the most common non-pulmonary vein
trigger?
A. Coronary sinus ostium
B. Left atrial appendage
C. Superior vena cava
D. Ligament of Marshall
C. Superior vena cava [CORRECT]
Rationale: The superior vena cava (SVC) contains myocardial extensions from the
sinus node region and is the most common non-pulmonary vein trigger for atrial
fibrillation, identified in 5-10% of cases. While the coronary sinus, left atrial
appendage, and ligament of Marshall can serve as triggers, the SVC is the
predominant non-PV source.
Correct Answer: C
, 4
Q6. During programmed atrial stimulation with extrastimuli, the atrial effective
refractory period (ERP) is defined as the longest S1-S2 coupling interval that fails to
produce which response?
A. Atrial capture
B. Atrial propagation
C. His bundle depolarization
D. Ventricular depolarization
B. Atrial propagation [CORRECT]
Rationale: The atrial ERP is defined as the longest coupling interval at which the
premature stimulus fails to propagate through atrial tissue, not merely fail to capture
locally. Local capture without propagation represents functional refractoriness; true
ERP requires failure of propagation beyond the stimulus site.
Correct Answer: B
Q7. A patient presents with a regular narrow-complex tachycardia at 150 bpm. Vagal
maneuvers produce transient AV block revealing flutter waves at 300 bpm. Which
anatomical circuit most likely sustains this arrhythmia?
A. AV node reentry circuit
B. Right atrial cavotricuspid isthmus-dependent circuit
C. Left atrial roof-dependent circuit
D. Sinoatrial nodal reentry circuit
B. Right atrial cavotricuspid isthmus-dependent circuit [CORRECT]
Rationale: Typical atrial flutter with 2:1 AV conduction at 150 bpm and flutter waves
at 300 bpm is sustained by a macroreentrant circuit in the right atrium involving the
cavotricuspid isthmus. AVNRT would not demonstrate independent atrial activity at
300 bpm; left atrial circuits produce atypical flutter patterns.
Correct Answer: B
IBHRE CCDS TEST FINAL EXAM 2026/2027 | Actual Exam 2
Versions A & B | Complete Accurate Questions with Detailed
Verified Answers | 100% Correct | Already Graded A+ | Pass
Guaranteed
[VERSION A - 60 QUESTIONS - ALREADY GRADED A+]
[A1: Cardiac Anatomy, Electrophysiology & Rhythm Analysis - Q1-15]
Q1. A 68-year-old patient presents with symptomatic bradycardia. An
electrophysiology study demonstrates that progressive prolongation of the A-H
interval occurs with atrial pacing at 500 ms cycle length before block distal to the His
bundle. This finding localizes the conduction delay to which structure?
A. Right bundle branch
B. Left anterior fascicle
C. AV node
D. Distal His-Purkinje system
C. AV node [CORRECT]
Rationale: The A-H interval represents conduction through the AV node; progressive
prolongation with atrial pacing is characteristic of AV nodal decremental conduction.
Distal His-Purkinje system block would manifest as sudden H-V prolongation or
block without preceding A-H prolongation. The other options represent infra-Hisian
conduction tissue.
Correct Answer: C
Q2. During an EP study, the earliest atrial activation during sinus rhythm is recorded
at the high right atrium. If the sinus node fails, which structure typically assumes
pacemaker dominance due to its fastest intrinsic automaticity?
A. AV node
B. Bundle of His
,2
C. Left atrial appendage
D. Ventricular myocardium
A. AV node [CORRECT]
Rationale: The AV node has the second-fastest intrinsic automaticity (40-60 bpm)
and serves as the primary escape pacemaker when sinus node function is lost.
Ventricular escape rhythms are slower (20-40 bpm), while the Bundle of His and left
atrial appendage do not serve as dominant escape pacemakers under normal
physiological hierarchy.
Correct Answer: A
Q3. A patient with a dual-chamber pacemaker is noted to have consistent 2:1
atrioventricular conduction during atrial pacing at 120 bpm. The native PR interval is
200 ms. Which anatomical structure most likely accounts for this fixed ratio block?
A. SA node exit block
B. AV node refractoriness
C. Right bundle branch block
D. Left posterior fascicular block
B. AV node refractoriness [CORRECT]
Rationale: Fixed 2:1 AV block during atrial pacing at rates between 100-150 bpm
typically results from AV nodal refractoriness, as the AV node has the longest
refractory period in the conduction system. Infra-Hisian block usually produces wider
QRS morphologies and often progresses to higher-grade block at lower rates.
Correct Answer: B
Q4. On a 12-lead ECG, a patient demonstrates a left bundle branch block pattern
with QRS duration of 148 ms. Which conduction fascicle is most likely blocked, and
what is the expected axis if the remaining fascicles are intact?
,3
A. Right bundle branch; right axis deviation
B. Left anterior fascicle; left axis deviation
C. Left posterior fascicle; right axis deviation
D. Left bundle branch; normal or right axis deviation
D. Left bundle branch; normal or right axis deviation [CORRECT]
Rationale: A left bundle branch block (LBBB) pattern with QRS ≥120 ms indicates
interruption of the left bundle branch main trunk or both fascicles. The remaining
right bundle branch conducts normally, producing typical LBBB morphology. Left axis
deviation suggests left anterior fascicular block superimposed on RBBB, not isolated
LBBB.
Correct Answer: D
Q5. A patient with atrial fibrillation undergoes electrophysiological mapping. The
arrhythmia is found to originate from muscular sleeves extending from the left
atrium into which structure, representing the most common non-pulmonary vein
trigger?
A. Coronary sinus ostium
B. Left atrial appendage
C. Superior vena cava
D. Ligament of Marshall
C. Superior vena cava [CORRECT]
Rationale: The superior vena cava (SVC) contains myocardial extensions from the
sinus node region and is the most common non-pulmonary vein trigger for atrial
fibrillation, identified in 5-10% of cases. While the coronary sinus, left atrial
appendage, and ligament of Marshall can serve as triggers, the SVC is the
predominant non-PV source.
Correct Answer: C
, 4
Q6. During programmed atrial stimulation with extrastimuli, the atrial effective
refractory period (ERP) is defined as the longest S1-S2 coupling interval that fails to
produce which response?
A. Atrial capture
B. Atrial propagation
C. His bundle depolarization
D. Ventricular depolarization
B. Atrial propagation [CORRECT]
Rationale: The atrial ERP is defined as the longest coupling interval at which the
premature stimulus fails to propagate through atrial tissue, not merely fail to capture
locally. Local capture without propagation represents functional refractoriness; true
ERP requires failure of propagation beyond the stimulus site.
Correct Answer: B
Q7. A patient presents with a regular narrow-complex tachycardia at 150 bpm. Vagal
maneuvers produce transient AV block revealing flutter waves at 300 bpm. Which
anatomical circuit most likely sustains this arrhythmia?
A. AV node reentry circuit
B. Right atrial cavotricuspid isthmus-dependent circuit
C. Left atrial roof-dependent circuit
D. Sinoatrial nodal reentry circuit
B. Right atrial cavotricuspid isthmus-dependent circuit [CORRECT]
Rationale: Typical atrial flutter with 2:1 AV conduction at 150 bpm and flutter waves
at 300 bpm is sustained by a macroreentrant circuit in the right atrium involving the
cavotricuspid isthmus. AVNRT would not demonstrate independent atrial activity at
300 bpm; left atrial circuits produce atypical flutter patterns.
Correct Answer: B
