HCA Healthcare Telemetry ECG Interpretation Guide
ACTUAL EXAM 2026/2027 | Complete Exam-Style
Questions with Detailed Rationales | 100% Verified Pass
Guaranteed – A+ Graded
Back to the Basics: Cardiac Anatomy, the Conduction System, and Electrophysiology
(Questions 1–15)
Q1: You're orienting a new telemetry tech, and she asks you what rate the SA node fires at
on its own. What do you tell her?
A. 20–40 beats/min
B. 60–100 beats/min [CORRECT]
C. 40–60 beats/min
D. 100–150 beats/min
Correct Answer: B
Rationale: The SA node is the heart's natural pacemaker and fires at an intrinsic rate of 60–
100 beats/min, which is why a normal resting rhythm lives in that range. The slower rates
belong to the AV junction and the ventricular escape pacemakers, which only take over if
the SA node fails.
Q2: If the SA node fails to fire, the AV junction normally takes over as the backup
pacemaker. At what intrinsic rate does the AV junction discharge?
A. 20–40 beats/min
B. 60–100 beats/min
C. 100–150 beats/min
D. 40–60 beats/min [CORRECT]
Correct Answer: D
Rationale: The AV junction has an intrinsic firing rate of 40–60 beats/min, making it the
heart's first line of backup below the sinus node. The Purkinje system fires even slower, at
20–40 beats/min, as the last resort.
Q3: A nursing student asks you which part of the conduction system fires at only 20–40
beats per minute. What's your answer?
A. Purkinje fibers [CORRECT]
B. SA node
C. AV node
D. Bundle of His
Correct Answer: A
,Rationale: Purkinje fibers are the slowest and last line of defense, firing at 20–40 beats/min.
The AV node and His bundle sit closer to 40–60, and the SA node runs 60–100.
Q4: An impulse generated by the SA node travels through the conduction system in which
order?
A. SA node → bundle branches → AV node → Purkinje fibers
B. AV node → SA node → His bundle → Purkinje fibers
C. SA node → AV node → His bundle → bundle branches → Purkinje fibers [CORRECT]
D. SA node → His bundle → AV node → Purkinje fibers
Correct Answer: C
Rationale: The impulse starts in the SA node, pauses briefly in the AV node, then races
through the His bundle, the bundle branches, and finally the Purkinje fibers. That fixed order
is why the P wave always precedes the QRS in a normally conducted beat.
Q5: Why does the AV node deliberately slow conduction before the impulse reaches the
ventricles?
A. To protect the ventricles from dangerously fast rates
B. To allow the atria time to contract and finish filling the ventricles [CORRECT]
C. To give the SA node time to recharge
D. To prevent backflow through the AV valves
Correct Answer: B
Rationale: That brief AV nodal delay, seen on the strip as the PR interval, buys the atria time
to complete their contraction so the ventricles fill fully — the atrial kick contributes a real
share of cardiac output. It's a filling issue, not a valve or protection issue.
Q6: On a rhythm strip, the P wave represents which event?
A. Atrial depolarization [CORRECT]
B. Atrial repolarization
C. Ventricular depolarization
D. Ventricular repolarization
Correct Answer: A
Rationale: The P wave is the electrical signature of atrial depolarization. Atrial repolarization
hides inside the QRS, while ventricular depolarization is the QRS itself and repolarization is
the T wave.
Q7: Which portion of the ECG reflects ventricular depolarization?
A. The PR segment
B. The P wave
C. The T wave
D. The QRS complex [CORRECT]
Correct Answer: D
Rationale: The QRS complex is ventricular depolarization, and it's normally narrow because
the specialized conduction system activates the ventricles almost simultaneously. The T
wave right behind it is repolarization.
Q8: What is the normal duration of the PR interval in an adult?
A. 0.06–0.10 second
, B. 0.04–0.12 second
C. 0.12–0.20 second [CORRECT]
D. 0.20–0.30 second
Correct Answer: C
Rationale: A normal PR interval runs 0.12 to 0.20 second, or three to five small boxes.
Anything longer suggests first-degree block, and anything shorter raises the question of
conduction starting somewhere other than the sinus node.
Q9: At standard paper speed, how much time does one small horizontal box on ECG paper
represent?
A. 0.04 second [CORRECT]
B. 0.12 second
C. 0.20 second
D. 0.40 second
Correct Answer: A
Rationale: One small box equals 0.04 second at the standard 25 mm/second speed, and five
small boxes — one large box — equal 0.20 second. That's the backbone of measuring
intervals by hand.
Q10: Routine telemetry rhythm strips are printed at which standard paper speed?
A. 50 mm/second
B. 25 mm/second [CORRECT]
C. 10 mm/second
D. 100 mm/second
Correct Answer: B
Rationale: The standard is 25 mm/second, and every usual measurement rule assumes that
speed. Faster speeds stretch the strip out and make rhythms look artificially slow and wide.
Q11: A post-op patient is in pain, febrile at 101.8°F, and anxious, and her telemetry shows
sinus tachycardia at 118. Which physiologic explanation best accounts for the faster rate?
A. Parasympathetic (vagal) stimulation of the SA node
B. Potassium pouring out of injured cells
C. Sympathetic stimulation releasing norepinephrine on the SA node [CORRECT]
D. Fever slowing conduction through the AV node
Correct Answer: C
Rationale: Pain, fever, and anxiety all fire up the sympathetic nervous system, and
norepinephrine makes the SA node depolarize faster. Vagal stimulation does the exact
opposite — it slows the node down.
Q12: Carotid sinus massage and the Valsalva maneuver slow the heart rate primarily by
doing what?
A. Blocking beta receptors in the SA node
B. Directly depolarizing the AV node
C. Increasing circulating catecholamines
D. Increasing vagal (parasympathetic) tone [CORRECT]
Correct Answer: D
ACTUAL EXAM 2026/2027 | Complete Exam-Style
Questions with Detailed Rationales | 100% Verified Pass
Guaranteed – A+ Graded
Back to the Basics: Cardiac Anatomy, the Conduction System, and Electrophysiology
(Questions 1–15)
Q1: You're orienting a new telemetry tech, and she asks you what rate the SA node fires at
on its own. What do you tell her?
A. 20–40 beats/min
B. 60–100 beats/min [CORRECT]
C. 40–60 beats/min
D. 100–150 beats/min
Correct Answer: B
Rationale: The SA node is the heart's natural pacemaker and fires at an intrinsic rate of 60–
100 beats/min, which is why a normal resting rhythm lives in that range. The slower rates
belong to the AV junction and the ventricular escape pacemakers, which only take over if
the SA node fails.
Q2: If the SA node fails to fire, the AV junction normally takes over as the backup
pacemaker. At what intrinsic rate does the AV junction discharge?
A. 20–40 beats/min
B. 60–100 beats/min
C. 100–150 beats/min
D. 40–60 beats/min [CORRECT]
Correct Answer: D
Rationale: The AV junction has an intrinsic firing rate of 40–60 beats/min, making it the
heart's first line of backup below the sinus node. The Purkinje system fires even slower, at
20–40 beats/min, as the last resort.
Q3: A nursing student asks you which part of the conduction system fires at only 20–40
beats per minute. What's your answer?
A. Purkinje fibers [CORRECT]
B. SA node
C. AV node
D. Bundle of His
Correct Answer: A
,Rationale: Purkinje fibers are the slowest and last line of defense, firing at 20–40 beats/min.
The AV node and His bundle sit closer to 40–60, and the SA node runs 60–100.
Q4: An impulse generated by the SA node travels through the conduction system in which
order?
A. SA node → bundle branches → AV node → Purkinje fibers
B. AV node → SA node → His bundle → Purkinje fibers
C. SA node → AV node → His bundle → bundle branches → Purkinje fibers [CORRECT]
D. SA node → His bundle → AV node → Purkinje fibers
Correct Answer: C
Rationale: The impulse starts in the SA node, pauses briefly in the AV node, then races
through the His bundle, the bundle branches, and finally the Purkinje fibers. That fixed order
is why the P wave always precedes the QRS in a normally conducted beat.
Q5: Why does the AV node deliberately slow conduction before the impulse reaches the
ventricles?
A. To protect the ventricles from dangerously fast rates
B. To allow the atria time to contract and finish filling the ventricles [CORRECT]
C. To give the SA node time to recharge
D. To prevent backflow through the AV valves
Correct Answer: B
Rationale: That brief AV nodal delay, seen on the strip as the PR interval, buys the atria time
to complete their contraction so the ventricles fill fully — the atrial kick contributes a real
share of cardiac output. It's a filling issue, not a valve or protection issue.
Q6: On a rhythm strip, the P wave represents which event?
A. Atrial depolarization [CORRECT]
B. Atrial repolarization
C. Ventricular depolarization
D. Ventricular repolarization
Correct Answer: A
Rationale: The P wave is the electrical signature of atrial depolarization. Atrial repolarization
hides inside the QRS, while ventricular depolarization is the QRS itself and repolarization is
the T wave.
Q7: Which portion of the ECG reflects ventricular depolarization?
A. The PR segment
B. The P wave
C. The T wave
D. The QRS complex [CORRECT]
Correct Answer: D
Rationale: The QRS complex is ventricular depolarization, and it's normally narrow because
the specialized conduction system activates the ventricles almost simultaneously. The T
wave right behind it is repolarization.
Q8: What is the normal duration of the PR interval in an adult?
A. 0.06–0.10 second
, B. 0.04–0.12 second
C. 0.12–0.20 second [CORRECT]
D. 0.20–0.30 second
Correct Answer: C
Rationale: A normal PR interval runs 0.12 to 0.20 second, or three to five small boxes.
Anything longer suggests first-degree block, and anything shorter raises the question of
conduction starting somewhere other than the sinus node.
Q9: At standard paper speed, how much time does one small horizontal box on ECG paper
represent?
A. 0.04 second [CORRECT]
B. 0.12 second
C. 0.20 second
D. 0.40 second
Correct Answer: A
Rationale: One small box equals 0.04 second at the standard 25 mm/second speed, and five
small boxes — one large box — equal 0.20 second. That's the backbone of measuring
intervals by hand.
Q10: Routine telemetry rhythm strips are printed at which standard paper speed?
A. 50 mm/second
B. 25 mm/second [CORRECT]
C. 10 mm/second
D. 100 mm/second
Correct Answer: B
Rationale: The standard is 25 mm/second, and every usual measurement rule assumes that
speed. Faster speeds stretch the strip out and make rhythms look artificially slow and wide.
Q11: A post-op patient is in pain, febrile at 101.8°F, and anxious, and her telemetry shows
sinus tachycardia at 118. Which physiologic explanation best accounts for the faster rate?
A. Parasympathetic (vagal) stimulation of the SA node
B. Potassium pouring out of injured cells
C. Sympathetic stimulation releasing norepinephrine on the SA node [CORRECT]
D. Fever slowing conduction through the AV node
Correct Answer: C
Rationale: Pain, fever, and anxiety all fire up the sympathetic nervous system, and
norepinephrine makes the SA node depolarize faster. Vagal stimulation does the exact
opposite — it slows the node down.
Q12: Carotid sinus massage and the Valsalva maneuver slow the heart rate primarily by
doing what?
A. Blocking beta receptors in the SA node
B. Directly depolarizing the AV node
C. Increasing circulating catecholamines
D. Increasing vagal (parasympathetic) tone [CORRECT]
Correct Answer: D
