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BSMH Advanced Arrhythmia Actual Exam 2026-2027 BANK
QUESTIONS WITH DETAILED VERIFIED ANSWERS EXAM
QUESTIONS WILL COME FROM HERE (100% CORRECT
ANSWERS A+ GRADED
1. Which ion current is primarily responsible for the rapid upstroke
(phase 0) of the ventricular action potential?
A. I-Kr
B. I-Ca-L
C. I-Na
D. I-f
Answer: C
Explanation: The rapid depolarization phase 0 in atrial and ventricular
myocytes, as well as Purkinje fibers, is driven by a large inward sodium
current (I-Na) through voltage-gated sodium channels. I-Ca-L sustains
the plateau phase, I-Kr contributes to repolarization, and I-f is the
pacemaker current in nodal cells.
2. The effective refractory period (ERP) of a cardiac cell is defined as the
interval during which:
A. A propagated action potential can be elicited by a normal stimulus
B. A stronger-than-normal stimulus can elicit a propagated response
C. No propagated action potential can be elicited, regardless of stimulus
strength
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D. The cell is in diastole
Answer: C
Explanation: The ERP corresponds to phases 0 through 3 of the action
potential, ending when the membrane has repolarized sufficiently for
sodium channels to recover from inactivation. During the ERP, even a
maximal stimulus cannot generate a propagated response.
3. A patient with atrial fibrillation has a ventricular rate of 150 bpm.
Which electrophysiological property of the AV node is primarily
responsible for limiting the ventricular rate?
A. Automaticity
B. Excitability
C. Conduction velocity
D. Decremental conduction and refractoriness
Answer: D
Explanation: The AV node exhibits decremental conduction; its cells
have a long refractory period that limits the number of impulses
conducted to the ventricles. During atrial fibrillation, hundreds of
impulses bombard the AV node, but only a fraction are transmitted due
to its refractory properties.
4. Early afterdepolarizations (EADs) are most likely to occur during
which phase of the action potential?
A. Phase 0
B. Phase 1
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C. Phase 2 or early Phase 3
D. Phase 4
Answer: C
Explanation: EADs are secondary depolarizations that occur before full
repolarization, typically during the plateau phase (phase 2) or early
phase 3. They are often facilitated by prolonged action potential
duration, such as in long QT syndrome, and can trigger torsades de
pointes.
5. Which of the following is characteristic of triggered activity due to
delayed afterdepolarizations (DADs)?
A. Occur during membrane repolarization
B. Are independent of heart rate
C. Occur after full repolarization and are enhanced by intracellular
calcium overload
D. Are suppressed by beta-adrenergic stimulation
Answer: C
Explanation: DADs arise after the membrane has fully repolarized
(phase 4). They result from spontaneous calcium release from the
sarcoplasmic reticulum, which activates the sodium-calcium exchanger
(NCX), generating a transient inward current. Conditions causing
intracellular calcium overload, such as digitalis toxicity, promote DADs.
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6. In the surface electrocardiogram, a Q wave that is greater than 0.04
seconds in duration and greater than 25% of the following R wave
amplitude suggests:
A. Left ventricular hypertrophy
B. Myocardial infarction
C. Early repolarization
D. Left bundle branch block
Answer: B
Explanation: Pathologic Q waves indicate electrically inert scar tissue
from a prior transmural myocardial infarction. The criteria include
duration of at least 40 ms (0.04 s) and depth at least 25% of the R wave
amplitude in anatomically contiguous leads.
7. A 12-lead ECG shows a wide QRS complex with a dominant S wave in
lead I and a dominant R wave in lead V1. This morphology is most
consistent with:
A. Left bundle branch block
B. Right bundle branch block
C. Wolff-Parkinson-White syndrome, Type A
D. Left anterior fascicular block
Answer: B
Explanation: Right bundle branch block (RBBB) delays depolarization of
the right ventricle, producing a secondary R wave (R') in right precordial
leads (V1–V2) and a deep, slurred S wave in left lateral leads (I, aVL, V5–
V6). The QRS duration is at least 120 ms.
BSMH Advanced Arrhythmia Actual Exam 2026-2027 BANK
QUESTIONS WITH DETAILED VERIFIED ANSWERS EXAM
QUESTIONS WILL COME FROM HERE (100% CORRECT
ANSWERS A+ GRADED
1. Which ion current is primarily responsible for the rapid upstroke
(phase 0) of the ventricular action potential?
A. I-Kr
B. I-Ca-L
C. I-Na
D. I-f
Answer: C
Explanation: The rapid depolarization phase 0 in atrial and ventricular
myocytes, as well as Purkinje fibers, is driven by a large inward sodium
current (I-Na) through voltage-gated sodium channels. I-Ca-L sustains
the plateau phase, I-Kr contributes to repolarization, and I-f is the
pacemaker current in nodal cells.
2. The effective refractory period (ERP) of a cardiac cell is defined as the
interval during which:
A. A propagated action potential can be elicited by a normal stimulus
B. A stronger-than-normal stimulus can elicit a propagated response
C. No propagated action potential can be elicited, regardless of stimulus
strength
,2|Page
D. The cell is in diastole
Answer: C
Explanation: The ERP corresponds to phases 0 through 3 of the action
potential, ending when the membrane has repolarized sufficiently for
sodium channels to recover from inactivation. During the ERP, even a
maximal stimulus cannot generate a propagated response.
3. A patient with atrial fibrillation has a ventricular rate of 150 bpm.
Which electrophysiological property of the AV node is primarily
responsible for limiting the ventricular rate?
A. Automaticity
B. Excitability
C. Conduction velocity
D. Decremental conduction and refractoriness
Answer: D
Explanation: The AV node exhibits decremental conduction; its cells
have a long refractory period that limits the number of impulses
conducted to the ventricles. During atrial fibrillation, hundreds of
impulses bombard the AV node, but only a fraction are transmitted due
to its refractory properties.
4. Early afterdepolarizations (EADs) are most likely to occur during
which phase of the action potential?
A. Phase 0
B. Phase 1
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C. Phase 2 or early Phase 3
D. Phase 4
Answer: C
Explanation: EADs are secondary depolarizations that occur before full
repolarization, typically during the plateau phase (phase 2) or early
phase 3. They are often facilitated by prolonged action potential
duration, such as in long QT syndrome, and can trigger torsades de
pointes.
5. Which of the following is characteristic of triggered activity due to
delayed afterdepolarizations (DADs)?
A. Occur during membrane repolarization
B. Are independent of heart rate
C. Occur after full repolarization and are enhanced by intracellular
calcium overload
D. Are suppressed by beta-adrenergic stimulation
Answer: C
Explanation: DADs arise after the membrane has fully repolarized
(phase 4). They result from spontaneous calcium release from the
sarcoplasmic reticulum, which activates the sodium-calcium exchanger
(NCX), generating a transient inward current. Conditions causing
intracellular calcium overload, such as digitalis toxicity, promote DADs.
, 4|Page
6. In the surface electrocardiogram, a Q wave that is greater than 0.04
seconds in duration and greater than 25% of the following R wave
amplitude suggests:
A. Left ventricular hypertrophy
B. Myocardial infarction
C. Early repolarization
D. Left bundle branch block
Answer: B
Explanation: Pathologic Q waves indicate electrically inert scar tissue
from a prior transmural myocardial infarction. The criteria include
duration of at least 40 ms (0.04 s) and depth at least 25% of the R wave
amplitude in anatomically contiguous leads.
7. A 12-lead ECG shows a wide QRS complex with a dominant S wave in
lead I and a dominant R wave in lead V1. This morphology is most
consistent with:
A. Left bundle branch block
B. Right bundle branch block
C. Wolff-Parkinson-White syndrome, Type A
D. Left anterior fascicular block
Answer: B
Explanation: Right bundle branch block (RBBB) delays depolarization of
the right ventricle, producing a secondary R wave (R') in right precordial
leads (V1–V2) and a deep, slurred S wave in left lateral leads (I, aVL, V5–
V6). The QRS duration is at least 120 ms.
