HCA EKG Interpretation Exam
Questions with Guaranteed Accurate Answers
Competency Cycle
HCA Healthcare
EKG Interpretation Certification & Annual Skills Validation
50 Questions | Nursing & Clinical Staff Competency
100% Accurate Answers | Latest Version
, Table of Contents
Section 1: Cardiac Anatomy & Electrophysiology (Q1–Q5)
Section 2: EKG Waveform Components (Q6–Q10)
Section 3: Normal Sinus & Sinus Rhythms (Q11–Q16)
Section 4: Atrial Rhythms (Q17–Q25)
Section 5: Junctional Rhythms (Q26–Q30)
Section 6: Ventricular Rhythms (Q31–Q40)
Section 7: AV Heart Blocks (Q41–Q45)
Section 8: Pacemaker Rhythms, ST/T Changes & Life-Threatening Arrhythmias (Q46–Q50)
, Section 1: Cardiac Anatomy & Electrophysiology (Q1–Q5)
1. Which structure serves as the primary pacemaker of the heart and normally generates
impulses at a rate of 60–100 beats per minute?
A) Sinoatrial (SA) node
B) Atrioventricular (AV) node
C) Bundle of His
D) Purkinje fibers
Rationale: The SA node, located in the upper wall of the right atrium near the superior vena cava,
is the heart's natural pacemaker due to its highest intrinsic rate of automaticity (60–100 bpm).
According to cardiac electrophysiology principles, the SA node overrides slower latent pacemakers
in the AV node (40–60 bpm), Bundle of His (40–60 bpm), and Purkinje fibers (20–40 bpm) under
normal conduction conditions.
2. In which order does the electrical impulse normally travel through the cardiac
conduction system?
A) SA node → AV node → Bundle of His → Bundle branches → Purkinje fibers
B) AV node → SA node → Bundle of His → Purkinje fibers → Bundle branches
C) SA node → Bundle of His → AV node → Bundle branches → Purkinje fibers
D) Purkinje fibers → Bundle branches → Bundle of His → AV node → SA node
Rationale: The normal cardiac conduction pathway begins at the SA node, travels through
internodal pathways to the AV node (where it briefly delays), then proceeds down the Bundle of
His, into the right and left bundle branches, and finally terminates in the Purkinje fiber network.
This sequential activation ensures coordinated atrial and ventricular contraction, and any
deviation from this pathway produces characteristic arrhythmias on the EKG.
3. What property of cardiac pacemaker cells allows them to spontaneously depolarize and
generate electrical impulses without external stimulation?
A) Automaticity
B) Conductivity
C) Contractility
D) Excitability
Rationale: Automaticity is the unique property of specialized cardiac pacemaker cells to
spontaneously depolarize during diastole (phase 4 of the action potential) by a slow inward
calcium current (If or funny current) through hyperpolarization-activated cyclic nucleotide-gated
(HCN) channels. Conductivity refers to impulse propagation speed, contractility to mechanical
shortening, and excitability to the cell's ability to respond to a stimulus—all distinct
electrophysiologic properties.
4. During which phase of the ventricular action potential is the myocardial cell absolutely
refractory and unable to respond to any new stimulus regardless of strength?
A) Phase 2 (Plateau phase)
B) Phase 0 (Rapid depolarization)
C) Phase 3 (Rapid repolarization)
D) Phase 4 (Resting potential)
Rationale: Phase 2 (plateau phase) corresponds to the absolute refractory period during which the
fast sodium channels are inactivated and no stimulus, regardless of magnitude, can elicit a new
depolarization. This refractory mechanism prevents tetany of the cardiac muscle and protects
against re-entrant arrhythmias. The relative refractory period begins during Phase 3 when some
cells may respond to a stronger-than-normal stimulus.
5. Which ion channel is primarily responsible for the rapid upstroke (Phase 0) of the
ventricular myocardial action potential?
A) Fast sodium channels
Questions with Guaranteed Accurate Answers
Competency Cycle
HCA Healthcare
EKG Interpretation Certification & Annual Skills Validation
50 Questions | Nursing & Clinical Staff Competency
100% Accurate Answers | Latest Version
, Table of Contents
Section 1: Cardiac Anatomy & Electrophysiology (Q1–Q5)
Section 2: EKG Waveform Components (Q6–Q10)
Section 3: Normal Sinus & Sinus Rhythms (Q11–Q16)
Section 4: Atrial Rhythms (Q17–Q25)
Section 5: Junctional Rhythms (Q26–Q30)
Section 6: Ventricular Rhythms (Q31–Q40)
Section 7: AV Heart Blocks (Q41–Q45)
Section 8: Pacemaker Rhythms, ST/T Changes & Life-Threatening Arrhythmias (Q46–Q50)
, Section 1: Cardiac Anatomy & Electrophysiology (Q1–Q5)
1. Which structure serves as the primary pacemaker of the heart and normally generates
impulses at a rate of 60–100 beats per minute?
A) Sinoatrial (SA) node
B) Atrioventricular (AV) node
C) Bundle of His
D) Purkinje fibers
Rationale: The SA node, located in the upper wall of the right atrium near the superior vena cava,
is the heart's natural pacemaker due to its highest intrinsic rate of automaticity (60–100 bpm).
According to cardiac electrophysiology principles, the SA node overrides slower latent pacemakers
in the AV node (40–60 bpm), Bundle of His (40–60 bpm), and Purkinje fibers (20–40 bpm) under
normal conduction conditions.
2. In which order does the electrical impulse normally travel through the cardiac
conduction system?
A) SA node → AV node → Bundle of His → Bundle branches → Purkinje fibers
B) AV node → SA node → Bundle of His → Purkinje fibers → Bundle branches
C) SA node → Bundle of His → AV node → Bundle branches → Purkinje fibers
D) Purkinje fibers → Bundle branches → Bundle of His → AV node → SA node
Rationale: The normal cardiac conduction pathway begins at the SA node, travels through
internodal pathways to the AV node (where it briefly delays), then proceeds down the Bundle of
His, into the right and left bundle branches, and finally terminates in the Purkinje fiber network.
This sequential activation ensures coordinated atrial and ventricular contraction, and any
deviation from this pathway produces characteristic arrhythmias on the EKG.
3. What property of cardiac pacemaker cells allows them to spontaneously depolarize and
generate electrical impulses without external stimulation?
A) Automaticity
B) Conductivity
C) Contractility
D) Excitability
Rationale: Automaticity is the unique property of specialized cardiac pacemaker cells to
spontaneously depolarize during diastole (phase 4 of the action potential) by a slow inward
calcium current (If or funny current) through hyperpolarization-activated cyclic nucleotide-gated
(HCN) channels. Conductivity refers to impulse propagation speed, contractility to mechanical
shortening, and excitability to the cell's ability to respond to a stimulus—all distinct
electrophysiologic properties.
4. During which phase of the ventricular action potential is the myocardial cell absolutely
refractory and unable to respond to any new stimulus regardless of strength?
A) Phase 2 (Plateau phase)
B) Phase 0 (Rapid depolarization)
C) Phase 3 (Rapid repolarization)
D) Phase 4 (Resting potential)
Rationale: Phase 2 (plateau phase) corresponds to the absolute refractory period during which the
fast sodium channels are inactivated and no stimulus, regardless of magnitude, can elicit a new
depolarization. This refractory mechanism prevents tetany of the cardiac muscle and protects
against re-entrant arrhythmias. The relative refractory period begins during Phase 3 when some
cells may respond to a stronger-than-normal stimulus.
5. Which ion channel is primarily responsible for the rapid upstroke (Phase 0) of the
ventricular myocardial action potential?
A) Fast sodium channels
