ECG WORKOUT
EXERCISES IN ARRHYTHMIA
INTERPRETATION
8TH EDITION
• AUTHOR(S)JANE HUFF
TEST BANK
1
Reference
Ch. 1 — Anatomy & Physiology of the Heart — SA node location
and ECG origin
Question Stem (2–3 sentences)
A telemetry strip shows a regular rhythm at ~72 bpm with a P
wave before every QRS; P waves are upright in lead II and
identical in morphology. Which is the most likely pacemaker
origin and why, based on cardiac anatomy?
,Options
A. Sinus (SA) node origin
B. Low atrial focus
C. Junctional (AV) focus
D. Ventricular ectopic focus
Correct Answer
A
Rationales
Correct (A): The SA node sits in the high right atrium and
initiates impulses producing upright, uniform P waves in lead II;
a regular rate ~60–100 bpm with P before each QRS fits sinus
origin.
Incorrect (B): A low atrial focus typically produces P waves with
different morphology (often inverted or biphasic in lead II).
Incorrect (C): Junctional focus often has absent or
inverted/retrograde P waves and rates 40–60 bpm, inconsistent
with upright P waves before QRS.
Incorrect (D): Ventricular focus produces wide QRS complexes
without preceding normal P waves.
Teaching Point
Upright, identical P waves in lead II indicate SA node (sinus)
origin.
Citation
Huff, J. (2022). ECG Workout: Exercises in Arrhythmia
Interpretation (8th ed.). Ch. 1.
,2
Reference
Ch. 1 — Heart Chambers & Conduction Pathway — Atrial
depolarization and lead correlation
Question Stem
A monitor strip shows small-amplitude negative deflections in
lead II preceding narrow QRS complexes. Considering atrial
anatomy and lead placement, what is the best anatomic
explanation for negative P waves in lead II?
Options
A. Ectopic atrial focus low in the atrium (near AV junction) with
superior-to-inferior depolarization
B. SA nodal origin with normal conduction vector
C. Ventricular escape rhythm initiating QRS before atrial activity
D. Artifact from electrode misplacement
Correct Answer
A
Rationales
Correct (A): A low atrial focus depolarizes atria from low→high
producing negative P in lead II because electrical vector is
directed away from the positive pole of lead II.
Incorrect (B): SA nodal origin gives positive P in lead II as
depolarization moves toward lead II.
Incorrect (C): Ventricular escape produces wide QRS and absent
, preceding P waves; here P is present.
Incorrect (D): While electrode misplacement can change
morphology, consistent negative P waves preceding each QRS
suggest a true low atrial focus, not artifact.
Teaching Point
P-wave polarity reflects atrial depolarization vector relative to
lead axis.
Citation
Huff, J. (2022). ECG Workout (8th ed.). Ch. 1.
3
Reference
Ch. 1 — Cardiac Innervation — Vagal influence on sinus rate
Question Stem
A patient becomes nauseated and develops a regular rhythm
with rate 48 bpm on telemetry after carotid sinus massage
during an exam. Which physiologic mechanism best explains
the rate change, and what ECG finding supports vagal
stimulation?
Options
A. Increased parasympathetic (vagal) tone slowing SA node
automaticity — sinus bradycardia (P before each QRS).
B. Increased sympathetic tone causing sinus tachycardia —
rapid P waves.
C. AV nodal block producing wide QRS complexes without P
EXERCISES IN ARRHYTHMIA
INTERPRETATION
8TH EDITION
• AUTHOR(S)JANE HUFF
TEST BANK
1
Reference
Ch. 1 — Anatomy & Physiology of the Heart — SA node location
and ECG origin
Question Stem (2–3 sentences)
A telemetry strip shows a regular rhythm at ~72 bpm with a P
wave before every QRS; P waves are upright in lead II and
identical in morphology. Which is the most likely pacemaker
origin and why, based on cardiac anatomy?
,Options
A. Sinus (SA) node origin
B. Low atrial focus
C. Junctional (AV) focus
D. Ventricular ectopic focus
Correct Answer
A
Rationales
Correct (A): The SA node sits in the high right atrium and
initiates impulses producing upright, uniform P waves in lead II;
a regular rate ~60–100 bpm with P before each QRS fits sinus
origin.
Incorrect (B): A low atrial focus typically produces P waves with
different morphology (often inverted or biphasic in lead II).
Incorrect (C): Junctional focus often has absent or
inverted/retrograde P waves and rates 40–60 bpm, inconsistent
with upright P waves before QRS.
Incorrect (D): Ventricular focus produces wide QRS complexes
without preceding normal P waves.
Teaching Point
Upright, identical P waves in lead II indicate SA node (sinus)
origin.
Citation
Huff, J. (2022). ECG Workout: Exercises in Arrhythmia
Interpretation (8th ed.). Ch. 1.
,2
Reference
Ch. 1 — Heart Chambers & Conduction Pathway — Atrial
depolarization and lead correlation
Question Stem
A monitor strip shows small-amplitude negative deflections in
lead II preceding narrow QRS complexes. Considering atrial
anatomy and lead placement, what is the best anatomic
explanation for negative P waves in lead II?
Options
A. Ectopic atrial focus low in the atrium (near AV junction) with
superior-to-inferior depolarization
B. SA nodal origin with normal conduction vector
C. Ventricular escape rhythm initiating QRS before atrial activity
D. Artifact from electrode misplacement
Correct Answer
A
Rationales
Correct (A): A low atrial focus depolarizes atria from low→high
producing negative P in lead II because electrical vector is
directed away from the positive pole of lead II.
Incorrect (B): SA nodal origin gives positive P in lead II as
depolarization moves toward lead II.
Incorrect (C): Ventricular escape produces wide QRS and absent
, preceding P waves; here P is present.
Incorrect (D): While electrode misplacement can change
morphology, consistent negative P waves preceding each QRS
suggest a true low atrial focus, not artifact.
Teaching Point
P-wave polarity reflects atrial depolarization vector relative to
lead axis.
Citation
Huff, J. (2022). ECG Workout (8th ed.). Ch. 1.
3
Reference
Ch. 1 — Cardiac Innervation — Vagal influence on sinus rate
Question Stem
A patient becomes nauseated and develops a regular rhythm
with rate 48 bpm on telemetry after carotid sinus massage
during an exam. Which physiologic mechanism best explains
the rate change, and what ECG finding supports vagal
stimulation?
Options
A. Increased parasympathetic (vagal) tone slowing SA node
automaticity — sinus bradycardia (P before each QRS).
B. Increased sympathetic tone causing sinus tachycardia —
rapid P waves.
C. AV nodal block producing wide QRS complexes without P
