NHA Certified EKG Technician (CET) — Questions and Answers

Question 1: A junctional rhythm arising from the AV node typically produces which finding?

Sawtooth flutter waves
Upright P waves at 100 bpm
Wide QRS at 180 bpm
Inverted or absent P waves with a rate of 40-60 bpm (Correct answer)

Correct answer: Inverted or absent P waves with a rate of 40-60 bpm

Junctional rhythms arise near the AV node, causing inverted or absent P waves at a rate of about 40-60 bpm.

Question 2: Which artifact appears as consistent, fine, fast oscillations often caused by 60 Hz electrical sources?

Muscle tremor artifact
Wandering baseline
Somatic tremor
AC electrical interference (Correct answer)

Correct answer: AC electrical interference

Uniform fast oscillations are typically AC interference from nearby electrical equipment.

Question 3: When precordial electrodes are placed too high on the chest, which leads are most affected?

Only lead III
Only aVR and aVL
Precordial leads V1–V4 (Correct answer)
Limb leads I, II, III

Correct answer: Precordial leads V1–V4

Precordial leads V1–V4 are most sensitive to vertical misplacement because they overlie the upper heart; high placement alters R-wave progression and ST morphology.

Question 4: A wandering baseline artifact is most commonly caused by:

Nearby AC power lines
Muscle tremor
Poor electrode contact or patient movement/respiration (Correct answer)
Incorrect paper speed

Correct answer: Poor electrode contact or patient movement/respiration

Loose electrodes, lotion on skin, or breathing cause the baseline to drift.

Question 5: A patient receiving thrombolytic therapy (e.g., tPA) for STEMI may show which ECG change that indicates successful reperfusion?

Accelerated idioventricular rhythm (AIVR) (Correct answer)
Development of tall R waves in V1
New onset atrial fibrillation
Permanent complete heart block

Correct answer: Accelerated idioventricular rhythm (AIVR)

Accelerated idioventricular rhythm is a classic reperfusion arrhythmia seen shortly after a blocked coronary artery reopens, indicating successful thrombolysis.

Question 6: What is the correct action if a patient refuses an ECG that has been ordered?

Perform the ECG anyway since it is ordered
Sedate the patient first
Respect the refusal, document it, and notify the ordering clinician (Correct answer)
Skip documentation as it is a minor procedure

Correct answer: Respect the refusal, document it, and notify the ordering clinician

Competent patients have the legal right to refuse procedures; the technician must respect that right, thoroughly document the refusal, and promptly notify the ordering physician.

Question 7: What must the ECG technician document on every ECG recording?

Time only, since the machine stores other data
Patient name, date, time, technician ID, and any relevant clinical notes (Correct answer)
Only the patient's name
Machine serial number only

Correct answer: Patient name, date, time, technician ID, and any relevant clinical notes

Complete ECG documentation includes patient identifiers, date, time, recording technician, and any clinical circumstances (e.g., patient symptoms during recording) for medico-legal accuracy.

Question 8: "The QRS complex represents..." is how the nurse relates the QRS complex to the cardiac cycle.

"ventricular depolarization.” (Correct answer)
“atrial repolarization.”
"ventricular repolarization.”
“atrial depolarization.”

Correct answer: "ventricular depolarization.”

The QRS complex on an ECG tracing specifically represents ventricular depolarization, which is the electrical activation of the ventricles leading to their contraction. This is a rapid and strong electrical event, resulting in the largest deflection on the ECG. Atrial depolarization is represented by the P wave, and ventricular repolarization by the T wave.

Question 9: Which corrective action best addresses baseline wander caused by electrode movement?

Record only precordial leads
Increase paper speed
Apply the 60 Hz filter
Re-prep skin and reattach electrodes with proper adhesion (Correct answer)

Correct answer: Re-prep skin and reattach electrodes with proper adhesion

Proper skin preparation and secure electrode attachment reduce movement-related baseline wander by improving electrode stability and skin contact.

Question 10: What voltage does each large square on ECG paper represent at standard calibration?

2 mV
0.5 mV
5 mV
1 mV (Correct answer)

Correct answer: 1 mV

At standard calibration (10 mm/mV), each large square (10 small squares tall) represents 1 mV of voltage.

Question 11: Which standard governs the electrical safety requirements for ECG machines used in US hospitals?

Association for the Advancement of Medical Instrumentation (AAMI) / IEC 60601 standard (Correct answer)
OSHA bloodborne pathogens standard
CMS billing standard
FDA Drug Approval Standard

Correct answer: Association for the Advancement of Medical Instrumentation (AAMI) / IEC 60601 standard

AAMI/IEC 60601 standards specify patient safety requirements for medical electrical equipment, including maximum allowable leakage currents for ECG machines.

Question 12: The QRS complex normally has a duration of:

0.12–0.20 seconds
Greater than 0.20 seconds
0.06–0.10 seconds (Correct answer)
Less than 0.04 seconds

Correct answer: 0.06–0.10 seconds

A normal QRS duration is 0.06–0.10 seconds; values ≥0.12 seconds indicate intraventricular conduction delay such as bundle branch block.

Question 13: An 'electrode pop' artifact on an ECG is characterized by:

Gradual baseline drift
Wide QRS complexes
Uniform 60 Hz oscillation
Sudden sharp deflection or signal loss in one lead (Correct answer)

Correct answer: Sudden sharp deflection or signal loss in one lead

Electrode pop is caused by a momentary loss of electrode contact, producing a sudden sharp spike or abrupt signal disruption in one or more leads.

Question 14: Nitroglycerin relieves angina but its primary ECG effect during an acute ischemic episode would be:

Causing peaked T waves
Widening the QRS complex
Reducing or resolving ST segment depression or elevation as ischemia improves (Correct answer)
Producing a new left bundle branch block

Correct answer: Reducing or resolving ST segment depression or elevation as ischemia improves

Nitroglycerin reduces myocardial oxygen demand and improves coronary perfusion; resolution of ischemia-induced ST changes confirms its effectiveness.

Question 15: Wandering baseline artifact on an ECG tracing is most often caused by:

High paper speed
Correct electrode placement
A fully charged machine
Patient movement or respiration (Correct answer)

Correct answer: Patient movement or respiration

Baseline wander commonly results from patient movement, breathing, or loose electrodes.

Question 16: When treating atrial fibrillation, which of the following is NOT a rate-controlling medication?

Metoprolol
Amlodipine (Correct answer)
Diltiazem
Digoxin

Correct answer: Amlodipine

Amlodipine is a dihydropyridine calcium channel blocker primarily used to treat hypertension and angina, and it does not significantly affect heart rate. Metoprolol (beta-blocker), Diltiazem (non-dihydropyridine calcium channel blocker), and Digoxin are all commonly used medications that slow the ventricular rate in atrial fibrillation by affecting AV nodal conduction.

Question 17: What structure is normally the heart's primary pacemaker?

Atrioventricular (AV) node
Purkinje fibers
Bundle of His
Sinoatrial (SA) node (Correct answer)

Correct answer: Sinoatrial (SA) node

The SA node in the right atrium initiates the normal heartbeat and sets the heart rate.

Question 18: What does an ECG technologist do when encountering a life-threatening rhythm?

Attempt to treat the patient independently
Immediately alert the supervising physician or activate the emergency response system per facility protocol (Correct answer)
Continue recording without interruption
Wait until the recording is complete before acting

Correct answer: Immediately alert the supervising physician or activate the emergency response system per facility protocol

When a life-threatening rhythm is identified (VF, VT, asystole, complete heart block), the technologist must immediately alert the physician or activate the emergency response system while maintaining patient safety.

Question 19: Under HIPAA, sharing a patient's ECG tracing with a family member without consent is:

Permitted because ECG results are not diagnostic information
A HIPAA violation that can result in civil and criminal penalties (Correct answer)
Only prohibited if the patient objects verbally
Acceptable if the family member is present

Correct answer: A HIPAA violation that can result in civil and criminal penalties

ECG results are protected health information (PHI) under HIPAA; disclosing them without proper authorization constitutes a privacy breach with serious legal consequences.

Question 20: What does the P wave on an ECG tracing represent?

Ventricular repolarization
Atrial depolarization (Correct answer)
Ventricular depolarization
Atrial repolarization

Correct answer: Atrial depolarization

The P wave reflects the electrical impulse spreading through the atria, causing atrial depolarization.

Question 21: Which artifact is most likely caused by patient muscle tremor or shivering?

Flat line
60-cycle interference
Somatic (muscle) tremor artifact (Correct answer)
Wandering baseline

Correct answer: Somatic (muscle) tremor artifact

Muscle movement produces irregular, jagged somatic tremor artifact.

Question 22: A rhythm strip shows no identifiable P waves and a chaotic, irregularly irregular baseline with a ventricular rate of 130 bpm. What rhythm is this?

Atrial fibrillation (Correct answer)
First-degree AV block
Atrial flutter
Sinus tachycardia

Correct answer: Atrial fibrillation

Absent P waves with an irregularly irregular ventricular response is the hallmark of atrial fibrillation.

Question 23: An ECG technician notices a patient's rhythm strip shows bradycardia and first-degree AV block. Which medication history is most consistent with these findings?

Aspirin
Warfarin
Nitroglycerin
Metoprolol (beta-blocker) (Correct answer)

Correct answer: Metoprolol (beta-blocker)

Metoprolol, a beta-blocker, reduces heart rate and slows AV node conduction, commonly producing bradycardia and a prolonged PR interval (first-degree AV block).

Question 24: An irregularly irregular rhythm with no clear P waves is characteristic of:

Normal sinus rhythm
Atrial fibrillation (Correct answer)
Sinus bradycardia
First-degree AV block

Correct answer: Atrial fibrillation

Atrial fibrillation shows an irregularly irregular rhythm with absent discernible P waves.

Question 25: The ventricles serve as the heart's shipping ports.

FALSE (Correct answer)
TRUE

Correct answer: FALSE

This statement is false. While the ventricles are powerful pumping chambers that *eject* blood out of the heart, the atria are more accurately described as the 'receiving ports' for blood returning to the heart. The ventricles then *pump* this blood to the lungs (right ventricle) or the rest of the body (left ventricle), acting more like the 'shipping pumps' rather than the initial receiving ports.

Question 26: Lithium toxicity can cause which ECG finding that mimics a naturally occurring rhythm disturbance?

Delta waves in multiple leads
T wave flattening or inversion and sinoatrial block resembling sick sinus syndrome (Correct answer)
Prolonged QRS with right bundle branch block
ST elevation identical to Brugada pattern

Correct answer: T wave flattening or inversion and sinoatrial block resembling sick sinus syndrome

Lithium toxicity can flatten or invert T waves and disrupt SA node function, producing sinoatrial block or sinus arrest patterns similar to sick sinus syndrome.

Question 27: What is the recommended storage condition for ECG thermal paper?

High humidity to prevent static
Refrigerated at 4°C
Direct sunlight to keep dry
Cool, dry environment away from heat and chemicals (Correct answer)

Correct answer: Cool, dry environment away from heat and chemicals

ECG thermal paper should be stored in a cool, dry place away from heat, chemicals, and sunlight to prevent premature darkening of the thermal coating.

Question 28: Which component of the ECG machine converts analog electrical signals to digital data?

Isolation transformer
Galvanometer
Amplifier
Analog-to-digital converter (ADC) (Correct answer)

Correct answer: Analog-to-digital converter (ADC)

The analog-to-digital converter (ADC) transforms the continuous analog voltage signals from electrodes into discrete digital values for processing and storage.

Question 29: The SA node, the heart's natural pacemaker, is located in which chamber?

Right ventricle
Left ventricle
Right atrium (Correct answer)
Left atrium

Correct answer: Right atrium

The sinoatrial node sits in the upper wall of the right atrium.

Question 30: In lead placement, the V6 electrode is positioned at the:

Fourth intercostal space left of sternum
Second intercostal space
Midaxillary line at the same level as V4 (Correct answer)
Right sternal border

Correct answer: Midaxillary line at the same level as V4

V6 sits in the midaxillary line, horizontally in line with V4 and V5.

Question 31: Heparin and warfarin are anticoagulants that do NOT directly alter the ECG. Which ECG change may appear indirectly if anticoagulation reverses a pulmonary embolism?

Resolution of the S1Q3T3 pattern (Correct answer)
Development of peaked T waves
New delta waves in V1-V3
Shortened QRS duration

Correct answer: Resolution of the S1Q3T3 pattern

A pulmonary embolism can produce the S1Q3T3 pattern; successful anticoagulation and clot resolution can lead to normalization and disappearance of this pattern.

Question 32: What is the normal duration of the PR interval in adults?

0.40–0.60 seconds
0.04–0.10 seconds
0.20–0.40 seconds
0.12–0.20 seconds (Correct answer)

Correct answer: 0.12–0.20 seconds

The normal PR interval is 0.12–0.20 seconds (3–5 small squares at 25 mm/sec), representing conduction time from the SA node through the AV node.

Question 33: Before applying chest electrodes, the technician should first:

Set the machine speed to 50 mm/sec
Have the patient stand upright
Prepare the skin by cleaning and, if needed, clipping hair (Correct answer)
Apply electrodes over clothing

Correct answer: Prepare the skin by cleaning and, if needed, clipping hair

Proper skin prep, including cleaning and hair removal, ensures good electrode contact and a clear tracing.

Question 34: Which federal law requires healthcare facilities to maintain a safe electrical environment for patients receiving ECGs?

Sarbanes-Oxley Act
Fair Labor Standards Act
HIPAA Security Rule only
National Electrical Code (NEC) / Joint Commission EC standards for medical facilities (Correct answer)

Correct answer: National Electrical Code (NEC) / Joint Commission EC standards for medical facilities

Joint Commission Environment of Care (EC) standards, which reference the NEC and IEC 60601 requirements, mandate that healthcare facilities maintain safe electrical environments to protect patients.

Question 35: What is the significance of pathological Q waves on an ECG?

They only appear during exercise
They indicate electrolyte imbalance
They indicate previous myocardial infarction with irreversible tissue death in the affected area (Correct answer)
They are always a normal finding

Correct answer: They indicate previous myocardial infarction with irreversible tissue death in the affected area

Pathological Q waves (>1mm wide, >25% of R wave height) indicate prior transmural myocardial infarction where dead heart muscle has been replaced by scar tissue, serving as a permanent marker of past heart attack.

Question 36: The QT interval represents the total time for:

Atrial depolarization only
SA node recovery
AV node conduction only
Ventricular depolarization and repolarization (Correct answer)

Correct answer: Ventricular depolarization and repolarization

The QT interval spans from the start of the QRS to the end of the T wave, covering ventricular activity.

Question 37: What is a 12-lead ECG and why is it called that?

12 electrodes placed on the chest
12 separate ECG machines
An ECG taken over 12 minutes
A standard ECG recording using 10 electrodes that produce 12 different views of the heart's electrical activity (Correct answer)

Correct answer: A standard ECG recording using 10 electrodes that produce 12 different views of the heart's electrical activity

A 12-lead ECG uses 10 physical electrodes (4 limb, 6 precordial) to create 12 different electrical viewpoints of the heart, providing a comprehensive picture of cardiac electrical activity.

Question 38: What does a tall, sharp, isolated spike artifact on an ECG most commonly represent?

Ventricular ectopic beat
P-wave abnormality
Static electricity discharge or lead wire tap (Correct answer)
Pacemaker spike in a pacemaker patient

Correct answer: Static electricity discharge or lead wire tap

A tall, sharp, isolated spike not preceded by a P-wave and not followed by a QRS is typically a static electricity artifact from touching the lead wire or patient movement.

Question 39: Which artifact pattern can mimic ventricular fibrillation on an ECG?

Electrode pop
High-frequency muscle tremor artifact (Correct answer)
Respiratory artifact
Baseline wander

Correct answer: High-frequency muscle tremor artifact

Severe high-frequency muscle tremor, as seen in patients with Parkinson's disease or rigors, can produce an irregular pattern that closely mimics ventricular fibrillation.

Question 40: The T wave on a standard ECG represents:

Atrial depolarization
Ventricular depolarization
Ventricular repolarization (Correct answer)
AV node delay

Correct answer: Ventricular repolarization

The T wave reflects the recovery, or repolarization, of the ventricles.

Question 41: Which limb lead views the heart from the left arm to the left leg?

Lead II
aVR
Lead I
Lead III (Correct answer)

Correct answer: Lead III

Lead III records the potential between the left arm and left leg.

Question 42: The normal duration of a QRS complex in an adult is approximately:

0.20 to 0.40 seconds
0.12 to 0.20 seconds
0.06 to 0.10 seconds (Correct answer)
0.40 to 0.60 seconds

Correct answer: 0.06 to 0.10 seconds

A normal QRS complex lasts less than 0.12 seconds, typically 0.06 to 0.10.

Question 43: Second-degree AV block Type II (Mobitz II) is characterized by what pattern?

Prolonged PR with all beats conducting
Progressive PR lengthening then a dropped beat
Constant PR interval with intermittent dropped QRS complexes (Correct answer)
Complete AV dissociation

Correct answer: Constant PR interval with intermittent dropped QRS complexes

Mobitz II shows a fixed PR interval with sudden non-conducted P waves and dropped QRS complexes.

Question 44: Does an ECG not use electrical impulses or signals from the heart to identify whether a heart pattern is normal or abnormal?

TRUE
FALSE (Correct answer)

Correct answer: FALSE

This statement is false because an ECG *does* precisely use electrical impulses and signals from the heart to assess its function. The electrodes placed on the body detect these electrical currents, which are then translated into a waveform pattern. Analyzing this pattern allows clinicians to determine if the heart's electrical activity is normal or indicative of an abnormality.

Question 45: A delta wave on the ECG is associated with:

Wolff-Parkinson-White (WPW) syndrome pre-excitation (Correct answer)
Hyperkalemia
Left bundle branch block
Right ventricular hypertrophy

Correct answer: Wolff-Parkinson-White (WPW) syndrome pre-excitation

A delta wave is the slurred upstroke at the start of the QRS caused by accessory pathway pre-excitation in WPW syndrome, bypassing the AV node.

Question 46: What is the significance of a pathological Q wave on an ECG?

It indicates right atrial enlargement
It is always a normal septal q wave
It may represent transmural myocardial infarction (scar tissue) (Correct answer)
It indicates left bundle branch block

Correct answer: It may represent transmural myocardial infarction (scar tissue)

Pathological Q waves (≥40 ms wide or ≥25% of the QRS height) represent areas of electrically silent myocardium, typically indicating old transmural infarction.

Question 47: What is the purpose of the right leg (RL) electrode in ECG safety design?

Records right heart signals
Records the inferior wall
Serves as the electrical ground/reference to reduce interference and protect patient (Correct answer)
Controls paper speed

Correct answer: Serves as the electrical ground/reference to reduce interference and protect patient

The RL electrode is the driven right leg circuit that acts as electrical ground, reducing common-mode interference and providing a safety reference to protect the patient.

Question 48: A patient receiving IV adenosine for SVT would most likely show which transient ECG finding immediately after the dose?

Ventricular tachycardia
Atrial fibrillation
Prolonged QT interval
Complete heart block or brief asystole (Correct answer)

Correct answer: Complete heart block or brief asystole

Adenosine transiently blocks AV node conduction, often producing a brief period of complete heart block or asystole before normal rhythm resumes.

Question 49: What does an isolation transformer in an ECG machine provide?

Electrical safety by preventing direct current path to patient (Correct answer)
Better resolution of small waveforms
Higher voltage output
Faster paper speed

Correct answer: Electrical safety by preventing direct current path to patient

The isolation transformer electrically isolates the patient circuit from the power supply, protecting the patient from microshock and macroshock hazards.

Question 50: Osborn waves (J waves) on an ECG are associated with which condition?

Hyponatremia
Hypothermia (Correct answer)
Digoxin toxicity
Hyperthermia

Correct answer: Hypothermia

Osborn (J) waves are positive deflections at the J-point, most prominent in lateral leads, and are a characteristic ECG finding in hypothermia.

Question 51: A patient receiving IV procainamide (Class IA) for ventricular arrhythmia may develop which dangerous ECG pattern?

ST elevation in all leads
QRS widening greater than 50% of baseline (Correct answer)
PR shortening
Inverted P waves in lead II

Correct answer: QRS widening greater than 50% of baseline

Procainamide can widen the QRS by more than 50% of the baseline width, signaling toxicity and increased risk of proarrhythmia.

Question 52: Why is proper skin preparation important before applying ECG electrodes?

To sterilize the skin for surgery
To reduce skin impedance and ensure good electrical contact for accurate signal recording (Correct answer)
To prevent allergic reactions to electrode gel
It has no practical effect on the recording

Correct answer: To reduce skin impedance and ensure good electrical contact for accurate signal recording

Cleaning the skin with alcohol, removing excess hair, and mildly abrading the surface reduces skin impedance, ensuring good electrode contact and minimizing artifact in the ECG recording.

Question 53: How can a technician differentiate somatic artifact from a true cardiac arrhythmia?

Artifacts do not follow P-QRS-T pattern and disappear when patient is still (Correct answer)
Artifacts are always in all leads simultaneously
Artifacts only occur in limb leads
Artifacts always cause ST changes

Correct answer: Artifacts do not follow P-QRS-T pattern and disappear when patient is still

True cardiac arrhythmias maintain some organized P-QRS-T relationship across leads, while somatic artifact lacks this pattern and resolves when the patient relaxes or stops moving.

Question 54: Respiratory artifact causes the ECG baseline to undulate at approximately:

1 Hz
60 Hz
The patient's heart rate
The patient's respiratory rate (12–20 cycles/min) (Correct answer)

Correct answer: The patient's respiratory rate (12–20 cycles/min)

Respiratory artifact cycles at the patient's breathing rate (typically 12–20 breaths/min), producing slow, rhythmic baseline shifts synchronized with respiration.

Question 55: A rhythm shows a rate of 45 bpm with normal P waves, PR intervals, and QRS complexes. What is this rhythm?

Complete heart block
Atrial fibrillation
Sinus bradycardia (Correct answer)
Sinus tachycardia

Correct answer: Sinus bradycardia

A normal sinus pattern with a rate below 60 bpm is sinus bradycardia.

Question 56: Which interval is measured from the beginning of the Q wave to the end of the S wave?

PR interval
QT interval
ST segment
QRS duration (Correct answer)

Correct answer: QRS duration

The QRS duration is measured from the first deflection of the QRS complex (onset of Q or R) to the end of the S wave (J point), representing total ventricular depolarization time.

Question 57: On a normal ECG, which part of the conduction system creates the brief pause seen in the PR interval?

Purkinje fibers
Bundle of His
SA node
AV node (Correct answer)

Correct answer: AV node

The AV node deliberately delays the impulse, producing the PR interval and allowing ventricular filling.

Question 58: Which limb electrode is typically used as the ground (reference) electrode?

Right arm
Left leg
Left arm
Right leg (Correct answer)

Correct answer: Right leg

The right leg electrode serves as the ground reference.

Question 59: A patient taking quinidine (Class IA) develops a QTc of 560 ms. What is the most serious arrhythmia risk associated with this finding?

Sinus bradycardia
First-degree AV block
Torsades de pointes (Correct answer)
Atrial fibrillation

Correct answer: Torsades de pointes

Marked QT prolongation from quinidine predisposes to torsades de pointes, a potentially fatal polymorphic ventricular tachycardia.

Question 60: What does a prolonged QTc interval (>500 ms) indicate clinically?

Left ventricular hypertrophy
First-degree AV block
Increased risk of torsades de pointes ventricular tachycardia (Correct answer)
Normal variant in athletes

Correct answer: Increased risk of torsades de pointes ventricular tachycardia

A QTc >500 ms significantly increases the risk of torsades de pointes, a potentially fatal polymorphic ventricular tachycardia.

Question 61: A premature, wide, bizarre QRS complex that occurs earlier than expected with no preceding P wave is called what?

Premature atrial contraction (PAC)
Premature ventricular contraction (PVC) (Correct answer)
Sinus pause
Junctional escape beat

Correct answer: Premature ventricular contraction (PVC)

A wide, early QRS without a preceding P wave is a premature ventricular contraction.

Question 62: What type of battery backup is most important for an ECG machine used in mobile settings?

Solar panel
Alkaline AA batteries
Capacitor only
Rechargeable lithium-ion battery with sufficient runtime (Correct answer)

Correct answer: Rechargeable lithium-ion battery with sufficient runtime

A rechargeable lithium-ion battery with adequate runtime ensures the ECG machine operates reliably in mobile or emergency settings without AC power.

Question 63: In ventricular fibrillation, the ECG most characteristically shows what?

A flat isoelectric line
Regular narrow QRS at 75 bpm
Chaotic waveforms with no identifiable QRS complexes (Correct answer)
Sawtooth atrial waves

Correct answer: Chaotic waveforms with no identifiable QRS complexes

Ventricular fibrillation produces disorganized, chaotic deflections with no discernible QRS complexes.

Question 64: Tricyclic antidepressant (TCA) overdose is classically recognized on the ECG by:

Peaked T waves and shortened PR interval
Inverted T waves in lateral leads only
Shortened QT interval and slow heart rate
Widened QRS, right axis deviation, and prolonged QT (Correct answer)

Correct answer: Widened QRS, right axis deviation, and prolonged QT

TCA overdose causes sodium channel blockade (widened QRS), potassium channel blockade (prolonged QT), and rightward axis shift, which is a life-threatening combination.

Question 65: Before performing an ECG, the technician must obtain:

Insurance authorization only
Written consent signed by a physician
A physician's verbal order only, no patient interaction needed
Patient identification verification and verbal consent for the procedure (Correct answer)

Correct answer: Patient identification verification and verbal consent for the procedure

The technician must verify patient identity using two identifiers and explain the procedure to obtain the patient's informed consent before placing any electrodes.

Question 66: A wandering baseline artifact on an ECG is most often caused by:

A fast heart rate
Patient movement or loose electrodes (Correct answer)
AC electrical interference
A defective paper feed

Correct answer: Patient movement or loose electrodes

Baseline wander typically results from patient motion, respiration, or poorly attached electrodes.

Question 67: How many electrodes are placed on the body to record a standard 12-lead ECG?

6
10 (Correct answer)
15
12

Correct answer: 10

Ten electrodes (four limb and six chest) produce the 12 leads of a standard ECG.

Question 68: Which antiemetics would NOT cause the QT interval to lengthen?

Domperidone
Ondansetron
Metoclopramide (Correct answer)
Droperidol

Correct answer: Metoclopramide

Metoclopramide, while having some potential for neurological side effects, is generally not associated with significant QT interval prolongation. In contrast, Domperidone, Ondansetron, and Droperidol are well-known to carry a risk of dose-dependent QT prolongation, which can predispose patients to serious ventricular arrhythmias like Torsades de Pointes.

Question 69: Muscle tremor (somatic) artifact appears on an ECG as:

Irregular, jagged, rapid spikes (Correct answer)
A perfectly flat line
Missing QRS complexes
A slow smooth wave

Correct answer: Irregular, jagged, rapid spikes

Muscle tremor produces irregular, jagged spikes across the baseline.

Question 70: What ECG findings suggest hyperkalemia?

Tall peaked T waves, widened QRS, flattened P waves, and potentially sine wave pattern (Correct answer)
Short QT interval
Deep Q waves
Prominent U waves

Correct answer: Tall peaked T waves, widened QRS, flattened P waves, and potentially sine wave pattern

Hyperkalemia produces progressive ECG changes: peaked T waves, PR prolongation, P wave flattening, QRS widening, and eventually a sine wave pattern that can degenerate into ventricular fibrillation.

Question 71: Hypokalemia from loop diuretic use (e.g., furosemide) produces which characteristic ECG change?

Flat or inverted T waves and prominent U waves (Correct answer)
Elevated J-point with delta waves
Shortened QT interval
Peaked T waves and narrow QRS

Correct answer: Flat or inverted T waves and prominent U waves

Hypokalemia flattens or inverts the T wave and causes prominent U waves (deflection after the T wave) due to delayed ventricular repolarization.

Question 72: To reduce artifact from a patient who cannot stop shivering, the best technique is to:

Use only limb leads
Warm the patient with a blanket before retrying (Correct answer)
Increase paper speed to 50 mm/sec
Switch off the machine and wait

Correct answer: Warm the patient with a blanket before retrying

Warming a shivering patient reduces involuntary muscle activity, directly decreasing somatic (muscle tremor) artifact on the ECG tracing.

Question 73: Hypocalcemia (e.g., from loop diuretics or hypoparathyroidism) produces which ECG finding?

Prolonged QT interval due to a long ST segment (Correct answer)
Peaked T waves
Delta waves
Shortened QT interval

Correct answer: Prolonged QT interval due to a long ST segment

Hypocalcemia prolongs the ST segment, lengthening the QT interval, because calcium is essential for the plateau phase of the cardiac action potential.

Question 74: A regular narrow-complex tachycardia at 150 bpm with no visible P waves most likely represents what?

Sinus bradycardia
Ventricular tachycardia
Supraventricular tachycardia (Correct answer)
First-degree AV block

Correct answer: Supraventricular tachycardia

A regular narrow-complex tachycardia around 150 bpm is typically supraventricular tachycardia.

Question 75: 60-cycle (AC) interference on an ECG appears as:

A completely flat line
A thick, fuzzy fine oscillation on the baseline (Correct answer)
A slowly drifting baseline
Random spikes with no pattern

Correct answer: A thick, fuzzy fine oscillation on the baseline

AC interference produces uniform fine, fuzzy oscillations from nearby electrical sources.

Question 76: What is the proper position for a patient during a routine resting ECG?

Seated upright at 90°
Supine (lying flat) with arms at sides and legs uncrossed (Correct answer)
Standing
Left lateral decubitus position

Correct answer: Supine (lying flat) with arms at sides and legs uncrossed

The standard resting ECG is recorded with the patient supine, arms at the sides, and legs uncrossed to ensure consistent lead axis alignment and minimize artifact.

Question 77: In third-degree (complete) AV block, what is the relationship between P waves and QRS complexes?

PR interval progressively lengthens
Every P wave conducts to a QRS
P waves are absent
They are completely independent of each other (Correct answer)

Correct answer: They are completely independent of each other

In complete heart block the atria and ventricles beat independently, so P waves and QRS complexes have no fixed relationship.

Question 78: If the limb leads on the right and left arms are reversed, what change is commonly seen?

V1 becomes inverted
Lead I becomes inverted (Correct answer)
The QRS widens abnormally
The heart rate doubles

Correct answer: Lead I becomes inverted

Right/left arm lead reversal typically inverts lead I and can mimic pathology.

Question 79: What artifact appears on an ECG when a patient is shivering?

Baseline irregularity mimicking atrial fibrillation due to muscle tremor (Correct answer)
Perfectly regular sharp spikes
Large wandering baseline
Flat line (asystole)

Correct answer: Baseline irregularity mimicking atrial fibrillation due to muscle tremor

Muscle tremor from shivering creates an irregular, jagged baseline that can mimic atrial fibrillation or obscure the underlying rhythm, requiring patient warming and stillness.

Question 80: Which precordial lead is placed at the 5th intercostal space, midclavicular line?

V2
V6
V1
V4 (Correct answer)

Correct answer: V4

V4 is located at the 5th intercostal space along the midclavicular line.

Question 81: Which chest lead is placed at the fourth intercostal space to the right of the sternum?

V2
V4
V6
V1 (Correct answer)

Correct answer: V1

V1 sits at the fourth intercostal space just right of the sternum.

Question 82: Which artifact appears as a regular, uniform oscillation at 60 Hz on the ECG baseline?

Muscle tremor artifact
AC interference artifact (Correct answer)
Respiratory artifact
Baseline wander

Correct answer: AC interference artifact

AC interference produces a regular 60 Hz oscillation (fine zigzag) on the ECG baseline, caused by nearby electrical equipment or poor grounding.

Question 83: T-wave inversion in leads V1–V4 in an adult is most concerning for:

Normal variant
Atrial enlargement
First-degree AV block
Anterior ischemia or right heart strain (Correct answer)

Correct answer: Anterior ischemia or right heart strain

T-wave inversions in the anterior precordial leads (V1–V4) can indicate anterior wall ischemia, non-STEMI, or right ventricular strain and require clinical correlation.

Question 84: A normal adult resting heart rate typically falls within which range?

60 to 100 beats per minute (Correct answer)
120 to 160 beats per minute
30 to 50 beats per minute
100 to 140 beats per minute

Correct answer: 60 to 100 beats per minute

A normal resting sinus rhythm in adults is generally 60 to 100 beats per minute.

Question 85: The QT interval represents:

Sinoatrial conduction time
Atrial depolarization only
Total ventricular depolarization and repolarization (Correct answer)
AV nodal conduction time

Correct answer: Total ventricular depolarization and repolarization

The QT interval spans from the start of the QRS to the end of the T-wave, encompassing all of ventricular electrical activity (depolarization and repolarization).

Question 86: A normal adult resting heart rate falls within which range?

30-50 bpm
100-140 bpm
140-180 bpm
60-100 bpm (Correct answer)

Correct answer: 60-100 bpm

A normal adult resting heart rate is 60 to 100 beats per minute.

Question 87: The ST segment on the ECG represents:

His-Purkinje conduction
The period between ventricular depolarization and repolarization (plateau phase) (Correct answer)
P-wave production
Atrial repolarization

Correct answer: The period between ventricular depolarization and repolarization (plateau phase)

The ST segment corresponds to phase 2 (plateau) of the ventricular action potential, during which no net current flows and all cells are in an equally depolarized state.

Question 88: Which of the following describes a possible cardiac condition?

All of the above (Correct answer)
Fatigue
Shortness of breath
Chest pain
Heart palpitations

Correct answer: All of the above

Chest pain, heart palpitations, shortness of breath, and fatigue are all common symptoms that can indicate an underlying cardiac condition. These symptoms arise when the heart is not functioning optimally, potentially due to issues like ischemia, arrhythmias, or heart failure. Therefore, experiencing any of these warrants further medical evaluation for potential heart problems.

Question 89: What is the maximum safe leakage current from an ECG machine to the patient?

500 mA
10 µA (microamperes) for applied part in cardiac floating connection (Correct answer)
1 A
100 mA

Correct answer: 10 µA (microamperes) for applied part in cardiac floating connection

IEC 60601 limits patient auxiliary current (leakage) to 10 µA for cardiac floating-type connections, since even tiny currents can induce ventricular fibrillation if they reach the heart directly.

Question 90: A sawtooth baseline pattern with atrial waves at about 300 bpm and a regular 2:1 ventricular response best describes which rhythm?

Ventricular tachycardia
Atrial flutter (Correct answer)
Sinus rhythm
Atrial fibrillation

Correct answer: Atrial flutter

The sawtooth flutter waves near 300 bpm with a fixed conduction ratio are classic for atrial flutter.

Question 91: A PR interval that is consistently prolonged beyond 0.20 seconds but every P wave conducts to a QRS indicates which rhythm?

First-degree AV block (Correct answer)
Second-degree AV block Type I
Third-degree AV block
Normal sinus rhythm

Correct answer: First-degree AV block

A fixed, prolonged PR interval with every beat conducting defines first-degree AV block.

Question 92: What does a normal sinus rhythm look like on an ECG?

No P waves visible
Regular P waves before each QRS complex, consistent PR interval, rate 60-100 bpm, and upright P waves in lead II (Correct answer)
QRS complexes wider than 120ms
Irregular R-R intervals

Correct answer: Regular P waves before each QRS complex, consistent PR interval, rate 60-100 bpm, and upright P waves in lead II

Normal sinus rhythm shows regular rhythm with each P wave followed by a QRS complex, PR interval 0.12-0.20 seconds, QRS duration <0.12 seconds, and rate between 60-100 bpm.

Question 93: Which drug interaction should an ECG technician be aware of that can compound QT prolongation risk?

Aspirin plus warfarin
Amiodarone plus azithromycin (Correct answer)
Metoprolol plus lisinopril
Furosemide plus spironolactone

Correct answer: Amiodarone plus azithromycin

Amiodarone and azithromycin both independently prolong the QT interval; combining them significantly increases the risk of torsades de pointes.

Question 94: Which intercostal space is used as the starting landmark for locating V1?

4th (Correct answer)
5th
3rd
2nd

Correct answer: 4th

The 4th intercostal space is the reference for V1 and V2 placement.

Question 95: On standard ECG paper, how many seconds does one small (1 mm) box represent horizontally?

0.04 seconds (Correct answer)
0.20 seconds
0.01 seconds
0.10 seconds

Correct answer: 0.04 seconds

At the standard 25 mm/sec speed, each small horizontal box equals 0.04 seconds.

Question 96: Which class of antiarrhythmic drugs primarily works by blocking sodium channels and may widen the QRS complex?

Class I (Correct answer)
Class II
Class IV
Class III

Correct answer: Class I

Class I antiarrhythmics (e.g., lidocaine, flecainide) block sodium channels, slowing depolarization and widening the QRS complex.

Question 97: What is the minimum acceptable skin impedance reduction before recording a diagnostic ECG?

Impedance does not matter
Below 500,000 ohms (500 kΩ)
Below 1,000,000 ohms (1 MΩ)
Below 5,000 ohms (5 kΩ) (Correct answer)

Correct answer: Below 5,000 ohms (5 kΩ)

Skin impedance should ideally be below 5 kΩ per electrode site; skin preparation such as light abrasion and alcohol cleansing helps achieve this.

Question 98: Hyperkalemia caused by potassium-sparing diuretics (e.g., spironolactone) would first appear on the ECG as:

Flat T waves
Short PR interval
Peaked, narrow T waves (Correct answer)
Prolonged QT interval

Correct answer: Peaked, narrow T waves

The earliest ECG manifestation of hyperkalemia is tall, peaked (tented) T waves due to altered ventricular repolarization.

Question 99: What is the correct response if an ECG machine appears to have a damaged power cord?

Remove it from service immediately and report to biomedical engineering (Correct answer)
Use it carefully and report at the end of the shift
Wrap the damage with tape and continue use
Unplug and replug the cord to reset

Correct answer: Remove it from service immediately and report to biomedical engineering

Damaged electrical equipment poses a shock and fire hazard; it must be immediately removed from service and tagged for biomedical engineering inspection before further use.

Question 100: A wide-complex regular tachycardia at 180 bpm with no visible P waves is most concerning for which rhythm?

Sinus tachycardia
Ventricular tachycardia (Correct answer)
Atrial flutter
Junctional rhythm

Correct answer: Ventricular tachycardia

A regular wide-QRS tachycardia without P waves should be treated as ventricular tachycardia until proven otherwise.

Question 101: The QRS complex on an ECG primarily represents:

Ventricular depolarization (Correct answer)
SA node firing
Atrial repolarization
Atrial depolarization

Correct answer: Ventricular depolarization

The QRS complex reflects depolarization of the ventricles.

Question 102: When should the ECG technician wash or sanitize their hands?

Before and after every patient contact, following standard precautions (Correct answer)
Only before the procedure
Only after contact with body fluids
Only if gloves are not available

Correct answer: Before and after every patient contact, following standard precautions

Standard precautions require hand hygiene both before and after every patient encounter to prevent healthcare-associated infection transmission.

Question 103: Which limb electrode is considered the ground (neutral) and produces no tracing?

Left leg (LL)
Right arm (RA)
Left arm (LA)
Right leg (RL) (Correct answer)

Correct answer: Right leg (RL)

The right leg electrode serves as the ground/reference and does not generate a lead tracing.

Question 104: How many electrodes are placed on the chest in a standard 12-lead ECG?

Ten
Four
Six (Correct answer)
Twelve

Correct answer: Six

Six precordial (chest) electrodes are placed, V1 through V6, along with four limb electrodes.

Question 105: What does a jagged, irregular baseline on an ECG tracing most likely indicate?

Atrial fibrillation
Pacemaker malfunction
Ventricular tachycardia
Poor electrode contact or muscle artifact (Correct answer)

Correct answer: Poor electrode contact or muscle artifact

A jagged, irregular baseline is typically caused by poor electrode contact, patient movement, or muscle tremor artifact rather than a cardiac dysrhythmia.

Question 106: A nearly flat (isoelectric) tracing in lead I suggests which electrode problem?

Right arm and left arm electrode reversal or disconnection (Correct answer)
Precordial lead misplacement
Low battery
V1 electrode misplacement

Correct answer: Right arm and left arm electrode reversal or disconnection

Lead I measures the potential difference between RA and LA; if both electrodes are on the same limb or disconnected, lead I will appear flat or isoelectric.

Question 107: A corrected QT interval (QTc) is calculated to account for:

Lead placement differences
Heart rate variation (Correct answer)
Blood pressure
Patient age

Correct answer: Heart rate variation

QT interval lengthens at slower heart rates and shortens at faster rates; the QTc corrects for this, allowing comparison across different heart rates using Bazett's formula.

Question 108: Which ECG change is most commonly associated with digoxin toxicity?

Wide QRS with right bundle branch block pattern
Short QT interval and tall T waves
Peaked P waves and shortened PR interval
Prolonged PR interval and ST scooping (Correct answer)

Correct answer: Prolonged PR interval and ST scooping

Digoxin toxicity characteristically causes a prolonged PR interval and a 'scooped' or sagging ST segment depression.

Question 109: A patient taking amiodarone is most likely to show which ECG finding?

Shortened QT interval
Shortened PR interval
Prolonged QT interval (Correct answer)
Delta waves

Correct answer: Prolonged QT interval

Amiodarone prolongs ventricular repolarization, resulting in a prolonged QT interval on the ECG.

Question 110: A patient on a calcium channel blocker (e.g., verapamil) is expected to show which ECG change?

Elevated ST segments
Shortened PR interval
Widened QRS complex
Prolonged PR interval (Correct answer)

Correct answer: Prolonged PR interval

Calcium channel blockers slow conduction through the AV node, prolonging the PR interval on the ECG.

Question 111: When performing an ECG on a patient with a pacemaker, what should the technician note?

Record only precordial leads to avoid interference
Disable the pacemaker before recording
Document pacemaker presence and note pacemaker spikes on the tracing (Correct answer)
Use double paper speed

Correct answer: Document pacemaker presence and note pacemaker spikes on the tracing

The presence of a pacemaker should be noted in the documentation because pacemaker spikes alter waveform morphology and are essential context for accurate ECG interpretation.

Question 112: Which beta-blocker effect on the ECG helps an ECG technician recognize its therapeutic use?

Prolonged PR interval and slower heart rate (Correct answer)
Shortened PR interval and faster heart rate
Delta waves on multiple leads
Widened QRS and peaked T waves

Correct answer: Prolonged PR interval and slower heart rate

Beta-blockers slow AV node conduction, producing a prolonged PR interval, and reduce heart rate by decreasing SA node automaticity.

Question 113: Which action is required if an ECG technician notices a life-threatening arrhythmia on the tracing?

Immediately repeat the ECG to confirm
Notify the responsible clinician immediately and do not leave the patient alone (Correct answer)
File the ECG and wait for physician review
Disconnect the electrodes and inform the next shift

Correct answer: Notify the responsible clinician immediately and do not leave the patient alone

Critical ECG findings must be reported immediately to the responsible clinician; the technician should remain with the patient until qualified help arrives.

Question 114: An ECG technician documents a QTc of 480 ms in a patient newly started on haloperidol (antipsychotic). What is the most appropriate action?

Document the finding and alert the supervising clinician for evaluation (Correct answer)
Repeat the ECG in 30 days without notifying anyone
Ignore it; QTc up to 500 ms is always normal
Immediately stop the ECG recording and send the patient home

Correct answer: Document the finding and alert the supervising clinician for evaluation

A QTc ≥ 470 ms (men) or ≥ 480 ms (women) warrants clinical evaluation; the ECG technician should document the finding and promptly notify the supervising clinician.

Question 115: What is the correct action when a patient's diaphoresis (sweating) causes electrodes to slip?

Dry the skin thoroughly and use additional securing tape before reattaching (Correct answer)
Record the ECG immediately before more slipping occurs
Abandon the ECG
Switch to gel-free electrodes only

Correct answer: Dry the skin thoroughly and use additional securing tape before reattaching

Drying the skin thoroughly and securing electrodes with additional tape or cloth stabilizes electrode contact in diaphoretic patients, improving signal quality.

Question 116: When should an ECG machine undergo preventive maintenance calibration?

According to the manufacturer's schedule, typically annually (Correct answer)
Only after repairs
Only when the battery dies
Every 10 years

Correct answer: According to the manufacturer's schedule, typically annually

ECG machines require periodic preventive maintenance and calibration per manufacturer guidelines, usually annually, to ensure accurate and reliable recordings.

Question 117: On the ECG trace below, which rhythm is present?

First degree heart block (Correct answer)
Sinus Rhythm
Second degree heart block
Junctional escape rhyhm

Correct answer: First degree heart block

First-degree heart block is characterized by a prolonged PR interval (greater than 0.20 seconds) on an ECG, indicating a delay in electrical conduction from the atria to the ventricles through the AV node. Despite the delay, every P wave is followed by a QRS complex, meaning all atrial impulses are eventually conducted. This consistent but extended delay is the hallmark of first-degree AV block.

Question 118: Which of the following best describes an 'intermittent' artifact on an ECG?

Sporadic signal disruptions that come and go during recording (Correct answer)
Only occurs during calibration
A flat line throughout all leads
Continuous noise throughout the entire tracing

Correct answer: Sporadic signal disruptions that come and go during recording

Intermittent artifact appears and disappears during recording, often due to a loose lead wire connection or patient movement at irregular intervals.

Question 119: Three or more PVCs in a row at a rate over 100 bpm should be identified as what?

Ventricular tachycardia (Correct answer)
Atrial flutter
Sinus tachycardia
Bigeminy

Correct answer: Ventricular tachycardia

A run of three or more consecutive PVCs above 100 bpm meets the definition of ventricular tachycardia.

Question 120: When examining an ECG, the nurse compares the waveform's horizontal movement across the ECG paper to

Intensity.
Time. (Correct answer)
Amplitude.
Voltage.

Correct answer: Time.

On an ECG paper, the horizontal axis represents time, with each small square typically representing 0.04 seconds and each large square (5 small squares) representing 0.20 seconds. This allows for precise measurement of intervals and durations of various waves and complexes, which is critical for rhythm analysis and identifying conduction abnormalities. The vertical axis, in contrast, represents amplitude or voltage.

NHA Certified EKG Technician (CET)

The NHA CET exam certifies EKG technicians on patient safety, EKG acquisition, and rhythm analysis/interpretation, validating competency to perform electrocardiograms in clinical settings.

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35 min

Time Limit

70%

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Sources & references

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