# ECG Quiz with Answers PDF — Free Quiz for Nurses, Medical Students & Beginners ## ⚠️ Medical Disclaimer > **This article is for educational purposes only.** The information and quiz questions provided here are intended for healthcare education, student learning, and clinical knowledge testing. They are NOT a substitute for formal clinical training, professional medical advice, or patient care decisions. ECG interpretation in clinical practice requires hands-on training, supervised experience, and clinical context. Always defer to clinical expertise and established protocols for patient care decisions. --- ## Introduction Whether you are a nursing student preparing for a cardiology clinical placement, a medical student studying for your USMLE or finals, a junior doctor wanting to sharpen your ECG interpretation skills, a paramedic or emergency responder reviewing cardiac monitoring, or simply a healthcare professional who wants to test their ECG knowledge — finding a reliable, comprehensive **ECG quiz with answers PDF** in one place can take a long time. This page ends that search. We have compiled **150+ ECG quiz questions and answers** covering every level of ECG knowledge — organized into dedicated sections for **ECG basics, ECG interpretation, rhythms and arrhythmias, 12-lead ECG, heart blocks, and multiple choice** — with questions appropriate for beginners, nursing students, and medical students. **What you will find in this article:** - **ECG basics quiz** — what ECG is, how it works, normal values - **ECG interpretation quiz** — systematic approach and 10 steps - **ECG rhythms and arrhythmias quiz** — AF, VT, VF, SVT, and more - **12-lead ECG quiz** — lead positions, territories, and interpretation - **ECG multiple choice quiz** — with complete answer key - **ECG for beginners quiz** — foundational concepts - A complete **FAQ section** answering every ECG question people search for --- ## Table of Contents 1. [ECG Basics Quiz with Answers](#ecg-basics-quiz-with-answers) 2. [ECG Interpretation Quiz — 10 Steps](#ecg-interpretation-quiz--10-steps) 3. [ECG Rhythms and Arrhythmias Quiz](#ecg-rhythms-and-arrhythmias-quiz) 4. [12-Lead ECG Quiz](#12-lead-ecg-quiz) 5. [Heart Blocks ECG Quiz](#heart-blocks-ecg-quiz) 6. [ECG Quiz for Beginners](#ecg-quiz-for-beginners) 7. [ECG Multiple Choice Quiz with Answer Key](#ecg-multiple-choice-quiz-with-answer-key) 8. [Frequently Asked Questions](#frequently-asked-questions) 9. [Conclusion](#conclusion) --- ## ECG Basics Quiz with Answers Here are **25 ECG basics quiz questions** — covering the fundamental knowledge required for any ECG assessment: **Q1: What does ECG stand for?** A: **Electrocardiogram** — a recording of the electrical activity of the heart. Also written as **EKG** (from the German "Elektrokardiogramm") — both terms refer to the same test. **Q2: Is an EKG and an ECG the same thing?** A: Yes — **ECG** (electrocardiogram) and **EKG** (from the German Elektrokardiogramm) are the same test. EKG is commonly used in the United States; ECG is more common in the UK and internationally. The test is identical regardless of which abbreviation is used. **Q3: What does an ECG test tell you?** A: An ECG records the electrical impulses that trigger each heartbeat and provides information about: heart rate, heart rhythm (regular or irregular), evidence of previous heart attacks, evidence of current heart attack (STEMI), signs of heart block, left or right ventricular hypertrophy, electrolyte abnormalities (particularly potassium and calcium), drug effects on the heart, and some inherited heart conditions. **Q4: What are the 5 waves/points of the ECG?** A: The 5 main components of the ECG waveform: 1) **P wave** — atrial depolarization (the electrical activation of the atria); 2) **QRS complex** — ventricular depolarization (activation of the ventricles — the main pumping chambers); 3) **T wave** — ventricular repolarization (electrical recovery of the ventricles); 4) **PR interval** — time from atrial to ventricular activation (AV node conduction); 5) **ST segment** — early ventricular repolarization (elevation or depression here is clinically very significant). **Q5: What is a normal ECG result?** A: Normal ECG parameters: **Heart rate:** 60-100 bpm; **Rhythm:** Regular sinus rhythm; **P wave:** Present, upright in leads I, II, aVF, duration < 0.12 seconds; **PR interval:** 0.12-0.20 seconds (3-5 small squares); **QRS duration:** < 0.12 seconds (< 3 small squares); **QT interval:** < 0.44 seconds in men, < 0.46 seconds in women (corrected QTc); **ST segment:** Isoelectric (no significant elevation or depression); **T waves:** Upright in most leads (inverted in aVR normally). **Q6: What is the normal heart rate on an ECG?** A: Normal sinus rhythm is **60-100 beats per minute (bpm)**. Below 60 bpm = bradycardia; above 100 bpm = tachycardia. **Q7: What is a normal PR interval?** A: The normal PR interval is **0.12-0.20 seconds** (3-5 small squares at standard paper speed of 25mm/second). A prolonged PR interval (> 0.20 sec) suggests first-degree heart block. **Q8: What is a normal QRS duration?** A: The normal QRS duration is **< 0.12 seconds** (< 3 small squares). A wide QRS (≥ 0.12 sec) suggests bundle branch block, ventricular rhythm, or accessory pathway conduction. **Q9: What is the QT interval and why does it matter?** A: The QT interval represents the total duration of ventricular depolarization and repolarization — measured from the start of the QRS to the end of the T wave. A prolonged QTc (corrected for rate) predisposes to dangerous arrhythmias, especially **Torsades de Pointes** (a type of VT that can degenerate into VF). Many drugs can prolong the QT interval — this is a key drug safety consideration. **Q10: What does the P wave represent?** A: The P wave represents **atrial depolarization** — the electrical activation of the atria (right then left atrium), which causes atrial contraction. A normal P wave is small, smooth, and upright in leads I and II. **Q11: What does the QRS complex represent?** A: The QRS complex represents **ventricular depolarization** — the electrical activation of the ventricular myocardium that causes ventricular contraction (the main pumping action). It is the tallest part of the ECG waveform. **Q12: What does the T wave represent?** A: The T wave represents **ventricular repolarization** — the electrical recovery of the ventricular myocardium in preparation for the next beat. Peaked T waves can indicate hyperkalemia; flattened T waves may suggest hypokalemia or ischemia; T wave inversion can indicate ischemia or infarction. **Q13: What does the ST segment represent and why is it clinically important?** A: The ST segment represents early ventricular repolarization — it should be at the isoelectric (baseline) level. **ST elevation** (especially in two or more contiguous leads) is the hallmark of **STEMI** (ST-Elevation Myocardial Infarction) — a cardiac emergency requiring immediate reperfusion. **ST depression** suggests subendocardial ischemia or NSTEMI. **Q14: What is the 10-second rule for ECG?** A: At standard ECG paper speed (25mm/second), a standard 12-lead ECG strip captures **10 seconds** of cardiac electrical activity. This means you can count the number of QRS complexes in the 10-second strip and multiply by 6 to estimate heart rate per minute. It also means the rhythm assessment is based on 10 seconds of observation. **Q15: How many electrodes are placed for a 12-lead ECG?** A: A 12-lead ECG requires **10 electrodes** — placed in standardized positions — to generate 12 different views (leads) of the heart's electrical activity. This is a common examination question: 10 electrodes → 12 leads. **Q16: What diseases can an ECG show?** A: An ECG can show evidence of: **Myocardial infarction** (heart attack — acute or old), **Arrhythmias** (AF, VT, SVT, heart blocks), **Left/right ventricular hypertrophy**, **Electrolyte abnormalities** (hyperkalemia, hypokalemia, hypercalcemia), **Pericarditis** (saddle-shaped ST elevation), **Pulmonary embolism** (S1Q3T3 pattern, right heart strain), **Drug toxicity** (digoxin, antiarrhythmics, QT-prolonging drugs), **Wolff-Parkinson-White syndrome** (delta wave, short PR), and **Long QT syndrome**. **Q17: What diseases cannot be detected by ECG?** A: An ECG **cannot** reliably detect: valvular heart disease (requires echocardiography), coronary artery disease/heart blockage in the absence of ischemia or infarction, heart failure (though secondary changes may be visible), infective endocarditis, most pericardial effusions, congenital structural defects, and cholesterol levels/atherosclerosis. Many people with significant heart disease have a normal resting ECG. **Q18: What is the difference between ECG and echo?** A: **ECG** (electrocardiogram) records the electrical activity of the heart — it is excellent for diagnosing arrhythmias, conduction abnormalities, and evidence of myocardial infarction. **Echo** (echocardiogram or cardiac ultrasound) uses sound waves to create images of the heart's structure — it assesses heart valves, chamber sizes, wall motion, and ejection fraction. They are complementary tests measuring completely different aspects of cardiac function. **Q19: Can an ECG detect a heart blockage?** A: A resting ECG can detect **evidence of a previous myocardial infarction** (old Q waves, T wave changes) and **acute STEMI** (ST elevation). However, it cannot directly visualize coronary artery blockages (stenosis). Someone with significant coronary artery disease may have a completely normal resting ECG between episodes of ischemia. Coronary blockage assessment requires coronary angiography, CT coronary angiography, or stress testing. **Q20: Can anxiety affect an ECG?** A: Yes — anxiety and stress can affect ECG results: **Sinus tachycardia** (elevated heart rate) is common with anxiety; **ST segment changes** and **T wave changes** may occur due to sympathetic nervous system activation; **Hyperventilation** (common in anxiety/panic attacks) can cause T wave inversion and QT changes; **Premature beats** (PACs, PVCs) may be more frequent. A **panic attack** can produce ECG changes that mimic cardiac ischemia — making clinical context essential in interpretation. **Q21: Can stress affect an ECG?** A: Yes — both psychological stress and physical stress affect ECG. Psychological stress causes sympathetic activation raising heart rate and potentially causing rhythm changes. Physical stress testing (exercise ECG / stress ECG) is deliberately used to unmask ischemic ECG changes that are not present at rest — specifically ST depression during exercise suggests coronary artery disease. **Q22: What are the 4 cardiac rhythms everyone should know?** A: The 4 essential cardiac rhythms: 1) **Normal Sinus Rhythm (NSR)** — regular, rate 60-100 bpm, P wave before each QRS; 2) **Atrial Fibrillation (AF)** — irregularly irregular, no distinct P waves, narrow QRS; 3) **Ventricular Fibrillation (VF)** — chaotic waveform, no recognizable QRS, cardiac arrest rhythm; 4) **Asystole** — flat line (or very fine VF), cardiac arrest rhythm requiring CPR. **Q23: What is the most serious heart rhythm?** A: **Ventricular Fibrillation (VF)** is the most immediately life-threatening cardiac rhythm — the ventricles quiver chaotically without effective pumping, causing immediate cardiac arrest. It requires immediate defibrillation. **Pulseless Ventricular Tachycardia (pVT)** is also immediately life-threatening. **Complete Heart Block** (third degree) with a slow ventricular escape rhythm can also be life-threatening. **Q24: What is a 3-lead ECG vs a 12-lead ECG?** A: A **3-lead ECG** (using leads I, II, III or a 3-lead configuration) provides continuous cardiac monitoring — commonly used in emergency departments, ICUs, and ambulances for rhythm monitoring. It gives limited information about heart regions. A **12-lead ECG** provides 12 different electrical views of the heart, allowing assessment of the entire heart including localization of ischemia and infarction. All patients with suspected cardiac events should have a 12-lead ECG. **Q25: What are bad signs on an ECG?** A: Bad signs on an ECG requiring urgent attention: **ST elevation** (especially ≥1mm in contiguous limb leads or ≥2mm in precordial leads) — STEMI until proven otherwise; **Wide complex tachycardia** — assume VT until proven otherwise; **Complete heart block** — PR interval varies, no relationship between P and QRS; **Prolonged QTc** (>500ms) — high risk of Torsades; **Deep T wave inversions** — may indicate posterior MI or ischemia; **Broad QRS** (≥0.12s) in the context of tachycardia; **Bizarre axis** or **new LBBB** in acute setting. --- ## ECG Interpretation Quiz — 10 Steps Here are **20 quiz questions** based on the systematic 10-step ECG interpretation approach: ### The 10 Steps of ECG Interpretation **Q1: What is the first step in systematic ECG interpretation?** A: **Step 1 — Confirm the basics:** Verify the patient's name, date, paper speed (usually 25mm/sec), and calibration (10mm = 1mV standard). Check all 12 leads are properly recorded. **Q2: What is Step 2 of ECG interpretation?** A: **Step 2 — Calculate the heart rate:** Count the number of large squares between two consecutive R waves and divide 300 by this number (for regular rhythms). Or count QRS complexes in a 10-second strip and multiply by 6. **Q3: What is Step 3 of ECG interpretation?** A: **Step 3 — Assess the rhythm:** Is it regular or irregular? Measure the R-R intervals — are they consistent? Irregular rhythms include AF (irregularly irregular) and second-degree heart blocks (regularly irregular in some types). **Q4: What is Step 4 of ECG interpretation?** A: **Step 4 — Assess the P waves:** Is there a P wave before every QRS? Are the P waves normal in morphology (upright in I, II; inverted in aVR)? A normal P wave suggests the rhythm originates from the sinoatrial (SA) node. **Q5: What is Step 5 of ECG interpretation?** A: **Step 5 — Measure the PR interval:** Is the PR interval 0.12-0.20 seconds (3-5 small squares)? Prolonged PR = first-degree block. Variable PR = second-degree block (Mobitz type I). No relationship = third-degree (complete) block. **Q6: What is Step 6 of ECG interpretation?** A: **Step 6 — Assess the QRS complex:** Duration < 0.12 seconds (narrow)? Wide QRS suggests bundle branch block, ventricular rhythm, or WPW. Assess for Q waves (> 0.04 sec = pathological Q wave, suggesting old MI). **Q7: What is Step 7 of ECG interpretation?** A: **Step 7 — Assess the ST segment:** Is the ST segment isoelectric? ST elevation or depression in specific leads? The ST segment is the most clinically important component for detecting acute ischemia and infarction. **Q8: What is Step 8 of ECG interpretation?** A: **Step 8 — Assess the T waves:** Are T waves upright (normally upright in most leads, inverted in aVR)? T wave changes include: peaked T waves (hyperkalemia, early STEMI), inverted T waves (ischemia, strain, PE), and biphasic T waves (Wellens syndrome — critical LAD stenosis). **Q9: What is Step 9 of ECG interpretation?** A: **Step 9 — Measure the QT interval:** Measure from the start of Q to the end of T wave. Calculate the corrected QT (QTc) using Bazett's formula: QTc = QT / √RR interval. Normal QTc < 0.44 sec (men), < 0.46 sec (women). Prolonged QTc (> 0.50 sec) is an emergency. **Q10: What is Step 10 of ECG interpretation?** A: **Step 10 — Determine the axis:** The cardiac axis describes the overall direction of ventricular depolarization. Normal axis is -30° to +90°. Left axis deviation (LAD): -30° to -90° — seen in LBBB, left anterior fascicular block, inferior MI. Right axis deviation (RAD): +90° to +180° — seen in right ventricular hypertrophy, PE, RBBB, left posterior fascicular block. **Q11: How to read an ECG easily?** A: The easiest approach is **AEIOU** or the systematic 10-step method: Always use a systematic approach (rate, rhythm, P waves, PR interval, QRS, ST segment, T waves, QTc, axis). Never just look at the overall appearance — specific components must be measured. Practice with real ECG cases systematically applied — pattern recognition develops over time but should always be backed by systematic measurement. **Q12: What does "sinus rhythm" mean on an ECG?** A: Sinus rhythm means the heart's electrical impulse originates from the **sinoatrial (SA) node** — the heart's natural pacemaker in the right atrium. Criteria: P wave before every QRS, PR interval 0.12-0.20 sec, P wave morphology consistent (upright in I and II). Normal sinus rhythm = sinus rhythm with rate 60-100 bpm. **Q13: What does left axis deviation mean?** A: Left axis deviation (LAD) means the overall direction of ventricular depolarization is deviated to the left of the normal range (-30° to -90°). Causes: **Left anterior fascicular block** (most common), inferior myocardial infarction, left ventricular hypertrophy, LBBB, and Wolff-Parkinson-White with right-sided accessory pathway. **Q14: What is right ventricular hypertrophy on ECG?** A: Right ventricular hypertrophy (RVH) on ECG shows: **Right axis deviation**, tall R wave in V1 (R > S in V1), deep S waves in V5-V6, and right ventricular strain pattern (ST depression + T wave inversion in V1-V3). Caused by pulmonary hypertension, chronic lung disease (cor pulmonale), pulmonary stenosis, and some congenital heart diseases. **Q15: What is left ventricular hypertrophy on ECG?** A: Left ventricular hypertrophy (LVH) on ECG shows increased voltage in precordial leads. **Sokolow-Lyon criteria:** S in V1 + R in V5 or V6 > 35mm. **Cornell criteria:** R in aVL + S in V3 > 28mm (men) or > 20mm (women). Causes: hypertension (most common), aortic stenosis, hypertrophic cardiomyopathy. **Q16: What does delta wave mean on ECG?** A: A **delta wave** is a slurred upstroke at the beginning of the QRS complex — representing pre-excitation of the ventricles via an accessory pathway (Bundle of Kent) bypassing the AV node. The classic delta wave with short PR interval and wide QRS = **Wolff-Parkinson-White (WPW) syndrome**. People with WPW are at risk of SVT and (rarely) sudden cardiac death if AF develops. **Q17: What is the significance of Q waves on ECG?** A: **Pathological Q waves** (> 0.04 seconds wide AND > 25% of the subsequent R wave height in that lead) indicate **old myocardial infarction** — they represent areas of electrically inert (dead) myocardium. Location of Q waves identifies the territory: Q waves in II, III, aVF = inferior MI (RCA territory); V1-V4 = anterior MI (LAD territory); I, aVL, V5-V6 = lateral MI (circumflex territory). **Q18: What are poor R wave progression on ECG?** A: Normal R wave progression: the R wave gradually increases in size from V1 to V5 (transitional zone V3-V4). **Poor R wave progression (PRWP):** failure of normal R wave growth — R wave remains small or is absent across the precordial leads. Causes: previous anterior MI, left bundle branch block, left ventricular hypertrophy, reversed electrode placement. **Q19: What is the significance of bundle branch blocks?** A: Bundle branch blocks (BBB) indicate delayed conduction through one of the bundle branches — causing wide QRS (≥0.12 seconds) and abnormal QRS morphology: **LBBB** (Left BBB): broad, notched "M-shaped" QRS in V5-V6, broad "W-shaped" in V1-V2; **RBBB** (Right BBB): RSR' pattern ("bunny ears") in V1, broad S wave in V5-V6. New LBBB in acute chest pain = treat as STEMI equivalent. **Q20: What is concordance vs discordance in the context of LBBB?** A: In a patient with LBBB, **discordant ST changes** (ST elevation opposite to the QRS direction) are expected and normal. **Concordant ST elevation** (ST elevation in the same direction as the QRS) in the context of LBBB and acute chest pain = **Sgarbossa criteria** for acute MI — a critical diagnostic indicator. --- ## ECG Rhythms and Arrhythmias Quiz Here are **20 quiz questions on cardiac rhythms and arrhythmias**: **Q1: What are the 5 types of cardiac rhythm?** A: Five main rhythm categories: 1) **Normal Sinus Rhythm (NSR)** — normal; 2) **Supraventricular Tachyarrhythmias** — rhythms originating above the ventricles (AF, AFL, SVT); 3) **Ventricular Tachyarrhythmias** — rhythms originating in the ventricles (VT, VF); 4) **Bradyarrhythmias** — slow rhythms (sinus bradycardia, heart blocks, junctional rhythms); 5) **Agonal/Terminal Rhythms** — non-perfusing rhythms (PEA, asystole, agonal rhythm). **Q2: What is Atrial Fibrillation (AF) on ECG?** A: AF on ECG shows: **Irregularly irregular rhythm** (R-R intervals are completely variable — the most important characteristic), **absence of distinct P waves** (replaced by fibrillatory baseline — fine, chaotic undulations), and **narrow QRS** (unless aberrant conduction or BBB). AF is the most common sustained cardiac arrhythmia. Rate can be slow, normal, or fast depending on AV node conduction. **Q3: What is Atrial Flutter (AFL) on ECG?** A: AFL on ECG shows: **Sawtooth flutter waves** (F waves) at approximately 300 bpm, most visible in leads II, III, aVF and V1; **Regular or regularly irregular ventricular rate** (usually 150 bpm with 2:1 block — which is characteristic); **Narrow QRS** (unless aberrant conduction). AFL is often called a "halfway house" between normal rhythm and AF. **Q4: What is SVT (Supraventricular Tachycardia) on ECG?** A: SVT on ECG shows: **Regular narrow complex tachycardia**, rate typically 150-250 bpm, P waves may be difficult to see (buried in QRS or T wave), and abrupt onset/termination. The most common type is AVNRT (AV nodal re-entry tachycardia). SVT responds to vagal maneuvers (Valsalva) or adenosine. **Q5: What is Ventricular Tachycardia (VT) on ECG?** A: VT on ECG shows: **Broad complex tachycardia** (QRS ≥ 0.12 sec), rate typically 100-250 bpm, **AV dissociation** (P waves independent of QRS — the most specific feature), **capture beats** (occasional narrow QRS from sinus node capturing the ventricles), and **fusion beats** (intermediate morphology between sinus and ventricular beats). A broad complex tachycardia should be treated as VT until proven otherwise. **Q6: What is Ventricular Fibrillation (VF) on ECG?** A: VF shows a completely **chaotic, irregular waveform** with no recognizable QRS complexes — the baseline is irregular undulations of varying size. There is no effective cardiac output — the patient is in cardiac arrest. Treatment: immediate CPR and defibrillation. **Q7: What is the difference between VT and SVT with aberrancy?** A: Both can appear as broad complex tachycardias. VT is suggested by: history of structural heart disease (most specific historical factor), AV dissociation (P waves independent of QRS), concordance (all QRS deflections in same direction in V1-V6), extreme axis deviation, QRS ≥ 0.14 sec, Brugada criteria. When in doubt, treat as VT — it is the safer assumption. **Q8: What is sinus bradycardia?** A: Sinus bradycardia = sinus rhythm with heart rate < 60 bpm. Causes: athletes (normal), increased vagal tone, hypothyroidism, hypothermia, inferior MI affecting the SA node, drugs (beta-blockers, digoxin, calcium channel blockers), sick sinus syndrome. **Q9: What is sinus tachycardia?** A: Sinus tachycardia = sinus rhythm with heart rate > 100 bpm. Causes: fever, pain, anxiety, exercise, dehydration, anemia, hyperthyroidism, pulmonary embolism, sepsis, heart failure, drugs (caffeine, sympathomimetics). It is always a physiological response to something — finding the underlying cause is essential. **Q10: What is Torsades de Pointes (TdP)?** A: Torsades de Pointes (French: "twisting of the points") is a polymorphic ventricular tachycardia associated with prolonged QTc — the QRS axis rotates around the baseline, giving the appearance of a twisting ribbon. It often terminates spontaneously but can degenerate into VF. Causes: drug-induced QT prolongation, electrolyte abnormalities (hypokalemia, hypomagnesemia), congenital long QT syndrome. Treatment: magnesium IV, remove precipitating cause, correct electrolytes, temporary pacing. **Q11: What are premature ventricular complexes (PVCs)?** A: PVCs are early, ectopic beats originating in the ventricles — appearing as **wide, bizarre QRS complexes** on ECG without a preceding P wave, followed by a **compensatory pause**. Isolated PVCs are common in healthy individuals. Frequent PVCs (>10% of beats), PVC "runs" (bigeminy, trigeminy), or R-on-T phenomenon may indicate underlying cardiac pathology. **Q12: What is the S1Q3T3 pattern in pulmonary embolism?** A: The S1Q3T3 pattern (large S wave in lead I, Q wave in lead III, inverted T wave in lead III) is a classic but relatively insensitive sign of **acute pulmonary embolism** — seen in approximately 20% of PE cases. More common ECG findings in PE include: sinus tachycardia (most common), right heart strain pattern, new RBBB, AF, and T wave inversions in V1-V4. **Q13: What ECG changes occur in hyperkalemia?** A: ECG changes in hyperkalemia (high potassium) progress from mild to severe: **Mild (5.5-6.5 mEq/L):** Peaked, symmetrical "tented" T waves (especially in precordial leads); **Moderate (6.5-7.0 mEq/L):** Widening of QRS, prolonged PR interval, loss of P waves; **Severe (>7.0 mEq/L):** Very wide QRS, "sine wave" pattern, ventricular arrhythmias. Hyperkalemia is a medical emergency requiring immediate treatment. **Q14: What ECG changes occur in hypokalemia?** A: ECG changes in hypokalemia (low potassium): **U waves** (small positive deflection after the T wave — most characteristic finding), flattened or inverted T waves, prolonged QU interval (appearing as long QT), and increased risk of arrhythmias (particularly Torsades de Pointes and VF). **Q15: What is Wellens syndrome?** A: Wellens syndrome is a **pre-infarction pattern** indicating critical stenosis of the proximal left anterior descending (LAD) artery — associated with high risk of anterior MI without intervention. Identified by characteristic T wave changes in leads V2-V3 **during chest pain-free periods**: **Type A:** Biphasic T waves (positive then negative); **Type B:** Deeply symmetric T wave inversions. These patients need urgent coronary angiography. **Q16: What are the Brugada criteria for distinguishing VT from SVT with aberrancy?** A: The Brugada criteria (stepwise algorithm): 1) Is there absence of RS complex in ALL precordial leads? (If yes → VT); 2) Is the R to S interval > 100ms in any precordial lead? (If yes → VT); 3) Is there AV dissociation? (If yes → VT); 4) Do the morphology criteria for VT apply in V1-V2 AND V6? (If yes → VT). If all four are absent → SVT with aberrancy. **Q17: What is agonal rhythm on ECG?** A: An agonal rhythm is a very slow, irregular, wide complex ventricular rhythm (< 20 bpm) seen in dying hearts or immediately before asystole. It produces no effective cardiac output — it is a cardiac arrest rhythm requiring CPR. It should not be confused with an effective cardiac rhythm. **Q18: What is complete heart block (third-degree block) on ECG?** A: Complete (third-degree) heart block on ECG shows: **No relationship between P waves and QRS complexes** — the atria and ventricles are controlled by completely independent pacemakers. P waves march through at their own rate; QRS complexes occur at a slow, regular escape rate (40-60 bpm if junctional escape; 20-40 bpm if ventricular escape). Third-degree block is a medical emergency requiring urgent pacing. **Q19: What is pulseless electrical activity (PEA)?** A: PEA (previously called EMD — electromechanical dissociation) is a cardiac arrest state where **organized electrical activity is present on ECG but no effective pulse is generated**. The heart has electrical impulses but insufficient mechanical pumping function. Causes are remembered by the **4 H's and 4 T's**: Hypoxia, Hypovolemia, Hypothermia, Hyper/hypokalemia; Tension pneumothorax, Tamponade, Toxins/drugs, Thrombosis (PE or MI). **Q20: What are the 4 H's and 4 T's of cardiac arrest causes?** A: The reversible causes of cardiac arrest: **4 H's:** 1) Hypoxia; 2) Hypovolemia; 3) Hypothermia; 4) Hyper/hypokalemia (electrolyte abnormalities). **4 T's:** 1) Tension pneumothorax; 2) Tamponade (cardiac); 3) Toxins (drug overdose); 4) Thrombosis (pulmonary embolism or acute MI). All potentially treatable during CPR — identifying and treating these is the key to survival in non-shockable rhythms. --- ## 12-Lead ECG Quiz Here are **20 quiz questions on the 12-lead ECG**: **Q1: Why is it called a 12-lead ECG when only 10 electrodes are used?** A: Because the 10 electrodes generate **12 different electrical "views" (leads)** of the heart by measuring potential differences between different combinations of electrodes. The 12 leads are: **Limb leads:** I, II, III (bipolar); **Augmented limb leads:** aVR, aVL, aVF (unipolar); **Precordial (chest) leads:** V1, V2, V3, V4, V5, V6 (unipolar). **Q2: What does V1, V2, V3, V4, V5, V6 mean on ECG?** A: The V leads (precordial/chest leads) record the electrical activity of the heart from different positions across the chest wall: **V1:** Right sternal border, 4th intercostal space — overlies the right ventricle; **V2:** Left sternal border, 4th intercostal space; **V3:** Between V2 and V4; **V4:** Midclavicular line, 5th intercostal space — overlies the apex (left ventricle); **V5:** Anterior axillary line, same horizontal level as V4; **V6:** Mid-axillary line, same horizontal level — overlies the lateral left ventricle. **Q3: What is a 7-lead ECG?** A: A 7-lead ECG is not a standard configuration — you may be thinking of a **5-lead ECG** (used for continuous monitoring: 3 limb leads + V1 + V5) or confusion with the **12-lead ECG** (12 leads from 10 electrodes). Some Holter monitors and extended monitoring systems may use different lead configurations. A standard diagnostic ECG remains the 12-lead. **Q4: Which ECG leads look at the inferior wall of the heart?** A: The **inferior leads** are **II, III, and aVF** — they "look at" the inferior wall of the left ventricle, supplied primarily by the **Right Coronary Artery (RCA)** in most people. ST elevation in II, III, aVF with reciprocal ST depression in I and aVL = inferior STEMI. **Q5: Which ECG leads look at the anterior wall of the heart?** A: The **anterior leads** are **V1-V4** — they look at the anterior wall of the left ventricle, supplied by the **Left Anterior Descending (LAD) artery**. ST elevation in V1-V4 = anterior STEMI — one of the most serious MI locations. **Q6: Which ECG leads look at the lateral wall of the heart?** A: The **lateral leads** are **I, aVL, V5, and V6** — they look at the lateral wall of the left ventricle, typically supplied by the **Circumflex artery (Cx)** or diagonal branches of the LAD. ST elevation in I, aVL, V5-V6 = lateral STEMI. **Q7: What does "reciprocal change" mean on a 12-lead ECG?** A: Reciprocal changes are **ST depression in leads opposite to the territory of ST elevation** — they occur because ischemia/infarction in one wall is seen as "mirror image" depression in the opposite leads. Example: inferior STEMI (ST elevation in II, III, aVF) typically shows reciprocal ST depression in I and aVL. Reciprocal changes increase diagnostic confidence for STEMI. **Q8: How do you identify a posterior MI on ECG?** A: Posterior MI is "hidden" on standard 12-lead ECG — it shows as: **ST depression and tall R waves in V1-V3** (the mirror image of ST elevation posterior). Confirmatory: additional posterior leads (V7, V8, V9) show ST elevation. Posterior MI is often missed without actively looking for this pattern. **Q9: What is aVR and what does it show on ECG?** A: **aVR** (augmented Vector Right) looks at the heart from the right shoulder — it sees the "back of the heart." Normal findings: inverted P wave, QS or rS pattern, inverted T wave. **ST elevation in aVR** (≥1mm) with diffuse ST depression in other leads strongly suggests: **left main coronary artery occlusion or proximal LAD occlusion** — extremely high-risk finding requiring immediate cath lab activation. **Q10: What is a right-sided ECG and when is it used?** A: A right-sided ECG (V3R-V6R) places chest electrodes in mirror-image positions on the right chest wall — to assess the **right ventricle**. It is essential in: **inferior STEMI** (to rule out right ventricular infarction — which changes management; avoid nitrates and diuretics in RV infarct), and suspected right ventricular pathology. **ST elevation in V4R ≥ 1mm = right ventricular MI.** **Q11: What is the STEMI criteria on a 12-lead ECG?** A: STEMI criteria (new ST elevation at the J point): **≥1mm in ≥2 contiguous limb leads** (II, III, aVF or I, aVL), **≥2mm in ≥2 contiguous precordial leads** (V1-V6) for men aged ≥40, or **≥1.5mm** in women, or **new LBBB** with acute chest pain. The "10-minute rule" — door to ECG within 10 minutes for suspected cardiac chest pain. **Q12: What is NSTEMI and how does it differ from STEMI on ECG?** A: **STEMI** (ST-Elevation MI): ST elevation on ECG + elevated troponin = complete coronary occlusion → requires emergency reperfusion (primary PCI ideally within 90 minutes). **NSTEMI** (Non-ST-Elevation MI): no ST elevation (may show ST depression, T wave changes, or normal ECG) + elevated troponin = partial occlusion or complete occlusion without full-thickness infarction → requires urgent (but not necessarily emergency) coronary angiography. **Q13: What is the significance of T wave inversions in V1-V4?** A: T wave inversions in V1-V4 can indicate: **Anterior ischemia/infarction**, **right ventricular strain** (pulmonary embolism, cor pulmonale), **Wellens syndrome** (critical LAD stenosis — these are pre-infarction T wave changes), **Brugada pattern** (in right precordial leads), or **normal variant** (right bundle branch block morphology). Clinical context is essential for interpretation. **Q14: What does PR depression mean on an ECG?** A: **PR segment depression** (PR segment below the baseline) along with **saddle-shaped or concave upward ST elevation in multiple leads** is characteristic of **acute pericarditis** — inflammation of the pericardium. Unlike STEMI, the ST elevation in pericarditis is typically diffuse (present in most leads) and concave upward, rather than localized and convex upward. **Q15: What is the 10-second rule in ECG?** A: At standard ECG paper speed (25mm/sec), a standard ECG strip captures **10 seconds** of activity. Method for heart rate calculation: count the QRS complexes in a 10-second strip and multiply by 6 = beats per minute. This method is most accurate for irregular rhythms (like AF) where the R-R interval method gives variable results. --- ## Heart Blocks ECG Quiz Here are **15 quiz questions on heart blocks**: **Q1: What is a first-degree heart block?** A: First-degree heart block = **prolonged PR interval > 0.20 seconds** (>5 small squares) with every P wave followed by a QRS. It represents slowed conduction through the AV node — not a true "block." Usually benign; causes include increased vagal tone, inferior MI, electrolyte abnormalities, digoxin, beta-blockers. No treatment usually required. **Q2: What is Mobitz type I (Wenckebach) second-degree block?** A: Mobitz type I (Wenckebach) second-degree block shows **progressive lengthening of the PR interval** with each beat until a P wave fails to conduct (QRS dropped), then the cycle repeats. The PR interval starts short after the dropped beat and lengthens again. The AV node is the site of block. Usually benign, rarely requires pacing. **Q3: What is Mobitz type II second-degree block?** A: Mobitz type II shows **constant PR interval** (not lengthening) with sudden, unexpected failure of P wave conduction (dropped QRS) — usually in a regular pattern (e.g., 2:1, 3:1). The block is below the AV node (bundle of His or bundle branches). More serious than Mobitz I — can progress to complete heart block. Usually requires pacemaker implantation. **Q4: What is 2:1 block on ECG?** A: 2:1 block means **every alternate P wave fails to conduct** — two P waves for every QRS complex. It can represent either Mobitz I or Mobitz II (impossible to determine from 2:1 alone — need to see longer rhythm strips). The QRS width gives a clue: narrow QRS in 2:1 block suggests Mobitz I (AV node); wide QRS suggests Mobitz II (infranodal block). **Q5: What is third-degree (complete) heart block?** A: **Complete heart block** = complete failure of conduction from atria to ventricles. The atria and ventricles beat independently: P waves at their own rate (usually 60-80 bpm from SA node); QRS complexes at the escape rate (40-60 bpm if junctional; 20-40 bpm if ventricular escape). There is NO relationship between P waves and QRS complexes (AV dissociation). This is a cardiac emergency requiring urgent pacing. **Q6: What is left bundle branch block (LBBB) on ECG?** A: LBBB ECG features: **QRS ≥ 0.12 sec (broad)**; **"M-shaped" (notched) QRS in leads I, V5, V6** (RSR' pattern); **Broad "W-shaped" S wave in V1** (QS or rS pattern); **ST and T wave changes discordant to QRS direction** (expected in LBBB). New LBBB in acute chest pain = STEMI equivalent until proven otherwise. Remember: "WiLLiaM" (W in V1, M in V5/V6 = LBBB). **Q7: What is right bundle branch block (RBBB) on ECG?** A: RBBB ECG features: **QRS ≥ 0.12 sec**; **RSR' ("bunny ears" or "M-shaped") pattern in V1** — the most characteristic feature; **Broad S wave in I and V5-V6**; **ST depression and T wave inversion in V1-V3** (secondary changes). Remember: "MaRRoW" (M in V1, W in V6 = RBBB). Isolated RBBB is often a normal variant; new RBBB in acute setting requires investigation. **Q8: What is left anterior fascicular block (LAFB)?** A: LAFB is block of the anterior division of the left bundle. ECG shows: **Left axis deviation** (-45° to -90°), small Q waves in I and aVL with small R waves in II, III, and aVF (qR in I/aVL, rS in II/III/aVF), **normal QRS duration** (< 0.12 sec — LAFB alone does not widen the QRS). Common cause of left axis deviation. **Q9: What is bifascicular block?** A: Bifascicular block = block in two of the three fascicles: most commonly **RBBB + LAFB** (the most common bifascicular block — shows RBBB morphology + left axis deviation) or RBBB + LPFB. Bifascicular block is significant because it puts the patient at risk of progressing to complete heart block, particularly during acute MI or if PR interval is also prolonged (trifascicular block). **Q10: What is a paced rhythm on ECG?** A: A paced ECG shows: **Pacing spikes** (vertical lines — visible before the P wave in atrial pacing, before the QRS in ventricular pacing); **Wide, broad QRS** in ventricular pacing (similar to LBBB morphology with left ventricular pacing); **100% pacing** or **sensing and pacing** depending on the intrinsic heart rate. Standard STEMI criteria do not apply to paced rhythms — use Sgarbossa criteria. **Q11: What is sick sinus syndrome?** A: Sick sinus syndrome (SSS) = dysfunction of the SA node causing: sinus bradycardia, sinus pauses/arrest, sinoatrial exit block, and sometimes alternating bradycardia with tachycardia (**bradycardia-tachycardia syndrome** or "tachy-brady syndrome"). Management typically requires pacemaker implantation. **Q12: What are the causes of complete heart block?** A: Causes of complete heart block: **Inferior MI** (RCA occlusion affecting the AV node), **Anterior MI** (massive — affecting the bundle branches), **Lyme disease**, **Infiltrative diseases** (sarcoidosis, amyloidosis), **Medication toxicity** (digoxin, beta-blockers, calcium channel blockers), **Congenital complete heart block**, **Post-cardiac surgery**, **Idiopathic fibrosis** (Lenegre's disease — most common cause in elderly). **Q13: What is the difference between heart block and bundle branch block?** A: **Heart block** (first, second, or third degree) refers to delayed or failed conduction through the **AV node** — affecting the PR interval and P-QRS relationship. **Bundle branch block** (LBBB, RBBB) refers to failed conduction through one of the ventricular conduction branches — affecting the QRS morphology and duration. They can coexist (e.g., RBBB + first-degree block). **Q14: What is an escape rhythm?** A: An escape rhythm is an intrinsic pacemaker rhythm that takes over when the dominant pacemaker (SA node) fails or the conduction below it is blocked. Escape rhythms are slower than normal: **Junctional escape** (AV node pacemaker): 40-60 bpm, narrow QRS, no P waves or retrograde P waves; **Ventricular escape:** 20-40 bpm, wide bizarre QRS, AV dissociation. Escape rhythms are **protective** — never suppress an escape rhythm pharmacologically. **Q15: What is AV dissociation?** A: AV dissociation means the atria and ventricles are beating independently — controlled by different pacemakers. Causes include: **Complete (third-degree) heart block**, **Ventricular tachycardia** (most common cause of AV dissociation in tachycardia), **Accelerated junctional rhythm** (junctional pacemaker is faster than SA node — "isorhythmic dissociation"). AV dissociation in tachycardia = VT until proven otherwise. --- ## ECG Quiz for Beginners Here are **15 ECG quiz questions for beginners**: **Q1: What is the ECG paper speed and what are the measurements of each small and large square?** A: Standard ECG paper speed is **25 mm/second**. Each **small square** = 1mm = **0.04 seconds** horizontally and **0.1mV** vertically. Each **large square** (5 small squares) = 5mm = **0.20 seconds** horizontally and **0.5mV** vertically. These measurements are fundamental to all ECG interpretation. **Q2: How do you calculate heart rate from an ECG?** A: Two methods: 1) **Regular rhythm:** Count the large squares between two R waves and divide 300 by this number (300 ÷ large squares = rate). Mnemonic: 300, 150, 100, 75, 60, 50 for 1, 2, 3, 4, 5, 6 large squares. 2) **Any rhythm (especially irregular):** Count QRS complexes in a 10-second strip × 6 = rate per minute. **Q3: What does "calibration" mean on an ECG and why does it matter?** A: The calibration signal (a standard square wave at the beginning of the ECG) should be **10mm tall = 1mV** at standard calibration. If ECG is run at half-standard (5mm = 1mV), voltages will appear smaller — potentially missing LVH. If at double-standard, voltages appear larger. Always check calibration before interpreting voltage criteria. **Q4: What is sinus arrhythmia and is it normal?** A: Sinus arrhythmia is a variation in heart rate with the respiratory cycle — heart rate increases with inspiration and decreases with expiration. It is **completely normal** — especially in children, young adults, and athletes. It is caused by changes in vagal tone with breathing. On ECG: P waves are normal, PR interval is constant, but R-R intervals vary slightly with breathing. **Q5: What does "regular" mean when describing ECG rhythm?** A: A rhythm is **regular** when all R-R intervals are equal (or vary by ≤0.04 seconds). Compare the first and last R-R interval — if they are the same, the rhythm is regular. **Irregularly irregular** (variable, no pattern) is the hallmark of AF. **Regularly irregular** (variable but with a pattern) is seen in second-degree block or sinus arrhythmia. **Q6: What is the significance of the J point on an ECG?** A: The J point is the junction between the end of the QRS complex and the beginning of the ST segment. **ST elevation** is measured at the J point (or 60-80ms after the J point in some criteria). The J point is the reference for determining whether ST segments are elevated, depressed, or at the isoelectric baseline. **Q7: What does "axis" mean on an ECG and how do you determine it simply?** A: The cardiac axis describes the dominant direction of electrical spread through the ventricles during depolarization. Simple method using leads I and aVF: both positive = **normal axis** (0° to +90°); I positive, aVF negative = **left axis deviation**; I negative, aVF positive = **right axis deviation**; both negative = **extreme axis** ("northwest territory" — seen in VT, dextrocardia). **Q8: What does "concordance" mean in ECG interpretation?** A: **Concordance** means all QRS complexes in the precordial leads (V1-V6) point in the same direction — either all predominantly positive (positive concordance) or all predominantly negative (negative concordance). In a broad complex tachycardia, **positive concordance suggests VT** originating from the posterior wall. Concordance is one of the Brugada criteria for diagnosing VT. **Q9: What is the difference between a P wave and a flutter wave?** A: **P waves** (in sinus rhythm and most supraventricular rhythms) are small, smooth, rounded deflections occurring at the sinus rate (60-100/min); each is followed by a QRS. **Flutter waves** (in atrial flutter) are saw-tooth shaped deflections at approximately 300/min — they do not each have a QRS (typically every 2nd, 3rd, or 4th flutter wave conducts). Flutter waves are most prominent in leads II, III, aVF and V1. **Q10: What is a normal P wave on ECG?** A: Normal P wave: **Upright in leads I, II, aVF**; **Inverted in aVR**; **Duration < 0.12 seconds** (3 small squares); **Amplitude < 2.5mm** (2.5 small squares in limb leads); **Biphasic in V1** (small positive then negative component). Tall, peaked P waves (P pulmonale > 2.5mm in II) = right atrial enlargement. Broad, notched P waves (P mitrale > 0.12 sec in II) = left atrial enlargement. **Q11: What does "narrow complex" mean on ECG?** A: A narrow complex QRS means the QRS duration is **< 0.12 seconds** (< 3 small squares). It indicates that ventricular activation occurred normally through the His-Purkinje system (even if the rhythm is abnormal — e.g., AF has a narrow QRS because conduction is normal after the AV node). Narrow complex rhythms originate from or above the Bundle of His. **Q12: What does "wide complex" mean on ECG?** A: A wide complex QRS means QRS duration ≥ **0.12 seconds** (≥ 3 small squares). Causes: **Bundle branch block** (LBBB, RBBB), **Ventricular rhythm** (VT, ventricular ectopy, paced rhythm), **Pre-excitation** (WPW syndrome), **Hyperkalemia** (extreme QRS widening), or **Drug toxicity** (sodium channel blockers — tricyclic antidepressant overdose). **Q13: What are the most important normal ECG values to memorize?** A: The key normal ECG values: **Heart rate:** 60-100 bpm; **PR interval:** 0.12-0.20 sec (3-5 small squares); **QRS duration:** < 0.12 sec (< 3 small squares); **QTc:** < 0.44 sec (men), < 0.46 sec (women); **ST segment:** Isoelectric (0mm); **P wave amplitude:** < 2.5mm; **QRS axis:** -30° to +90°. **Q14: How to read an ECG — simple checklist for beginners:** A: The beginner's ECG checklist: 1) Check name, date, calibration; 2) What is the rate? (300 ÷ large squares); 3) Is the rhythm regular or irregular?; 4) Are there P waves? One before each QRS?; 5) What is the PR interval? (Normal 3-5 small squares); 6) What is the QRS width? (Normal < 3 small squares); 7) Any ST changes? (Elevation or depression?); 8) Are T waves upright?; 9) Any Q waves?; 10) What is your conclusion? **Q15: What is the best way to practice ECG interpretation?** A: Best approaches for ECG learning: 1) **Systematic method first** — always follow the same steps, never skip; 2) **Practice cases daily** — ecg.utah.edu, Life in the Fast Lane (LITFL), 123ECG are excellent free resources; 3) **Learn the key patterns** — STEMI morphology, AF, VT, BBB — recognize them at a glance; 4) **Ask a senior** — discuss real ECGs in clinical practice; 5) **Use quizzes** — like this page — to reinforce learning; 6) **Start simple** — master normal sinus rhythm before studying complex arrhythmias. --- ## ECG Multiple Choice Quiz with Answer Key Here are **20 multiple choice ECG quiz questions**: **1. What is the normal PR interval on ECG?** - A) 0.04-0.10 seconds - B) 0.12-0.20 seconds ✅ - C) 0.20-0.30 seconds - D) 0.10-0.12 seconds **2. What does ST elevation in leads II, III, and aVF suggest?** - A) Anterior STEMI - B) Posterior MI - C) Inferior STEMI ✅ - D) Lateral STEMI **3. Which rhythm shows "irregularly irregular" R-R intervals with no P waves?** - A) Sinus arrhythmia - B) Atrial Flutter - C) Atrial Fibrillation ✅ - D) Second-degree heart block **4. What does a prolonged QTc (> 500ms) predispose to?** - A) First-degree heart block - B) Atrial fibrillation - C) Torsades de Pointes ✅ - D) Sinus bradycardia **5. How many electrodes are used for a 12-lead ECG?** - A) 12 - B) 6 - C) 10 ✅ - D) 8 **6. "Peaked, symmetrical T waves" on ECG most suggests:** - A) Hypokalemia - B) Hyperkalemia ✅ - C) Hypocalcemia - D) Hypermagnesemia **7. What does AV dissociation in tachycardia suggest until proven otherwise?** - A) SVT with aberrancy - B) Atrial Flutter - C) Ventricular Tachycardia ✅ - D) Sinus tachycardia **8. What is the hallmark ECG finding in complete (3rd degree) heart block?** - A) Prolonged PR interval - B) Dropped QRS complexes - C) No relationship between P waves and QRS complexes ✅ - D) Wide QRS only **9. The RSR' ("bunny ears") pattern in V1 with a broad S wave in V6 indicates:** - A) Left Bundle Branch Block - B) Right Bundle Branch Block ✅ - C) Left Axis Deviation - D) Left Ventricular Hypertrophy **10. What does ST depression in leads V1-V3 with tall R waves suggest?** - A) Anterior STEMI - B) Posterior MI ✅ - C) Normal variant - D) Right Bundle Branch Block **11. In a 10-second ECG strip, you count 15 QRS complexes. What is the heart rate?** - A) 80 bpm - B) 90 bpm ✅ (15 × 6 = 90 bpm) - C) 100 bpm - D) 120 bpm **12. Which of the following is NOT a cause of sinus tachycardia?** - A) Fever - B) Pulmonary embolism - C) Athletic training ✅ (athletes typically have sinus bradycardia) - D) Anemia **13. What does the S1Q3T3 pattern suggest?** - A) Inferior MI - B) Pulmonary Embolism ✅ - C) Left ventricular hypertrophy - D) Pericarditis **14. New Left Bundle Branch Block in a patient with acute chest pain should be treated as:** - A) A normal finding, no action needed - B) Right bundle branch block equivalent - C) STEMI equivalent requiring urgent reperfusion ✅ - D) First-degree heart block **15. In Wenckebach (Mobitz I) second-degree block, what happens to the PR interval?** - A) It remains constant - B) It shortens progressively - C) It lengthens progressively until a QRS is dropped ✅ - D) It is absent **16. What is the most common cause of wide complex tachycardia?** - A) SVT with aberrancy - B) Ventricular Tachycardia ✅ - C) Atrial Flutter with BBB - D) Hyperkalemia **17. Delta waves on ECG are associated with:** - A) Hyperkalemia - B) First-degree heart block - C) Wolff-Parkinson-White syndrome ✅ - D) Left ventricular hypertrophy **18. "Diffuse saddle-shaped ST elevation" is characteristic of:** - A) STEMI - B) Pericarditis ✅ - C) Pulmonary Embolism - D) Left ventricular hypertrophy **19. The Sokolow-Lyon criteria for LVH requires:** - A) QRS duration > 0.12 sec - B) S in V1 + R in V5 or V6 > 35mm ✅ - C) PR interval > 0.20 sec - D) ST elevation in lateral leads **20. Which finding on ECG is the most reliable for diagnosing VT in a broad complex tachycardia?** - A) QRS width > 0.14 seconds - B) Right bundle branch block morphology - C) AV dissociation ✅ - D) Left axis deviation --- ## Frequently Asked Questions ### Q1: What does an ECG test tell you? An ECG records the electrical impulses of the heart and provides information about: **heart rate** (how fast the heart is beating), **heart rhythm** (regular or irregular, type of rhythm), **evidence of previous or current heart attack** (Q waves for old MI; ST elevation for acute STEMI), **conduction abnormalities** (heart blocks, bundle branch blocks), **chamber enlargement** (LVH, RVH, atrial enlargement), **electrolyte abnormalities** (peaked T waves in hyperkalemia, U waves in hypokalemia), **drug effects** (digoxin pattern, QT prolongation from drugs), and **some inherited conditions** (long QT syndrome, Brugada syndrome). ### Q2: What is a normal ECG result? A normal ECG shows: regular sinus rhythm at 60-100 bpm, normal P waves (upright in I and II) before every QRS, PR interval 0.12-0.20 seconds, narrow QRS < 0.12 seconds, isoelectric ST segment, upright T waves in most leads, and QTc within normal limits (< 0.44 sec men, < 0.46 sec women). However, a normal resting ECG does NOT exclude significant heart disease — many people with severe coronary artery disease have normal resting ECGs. ### Q3: What are the 5 points of the ECG? The 5 main ECG components: 1) **P wave** — atrial depolarization; 2) **QRS complex** — ventricular depolarization; 3) **T wave** — ventricular repolarization; 4) **PR interval** — AV conduction time; 5) **ST segment** — early repolarization (most critical for identifying ischemia). Some frameworks also include the U wave (after T wave — represents Purkinje fiber repolarization, best seen in hypokalemia) as a 6th component. ### Q4: What are the 10 steps of ECG interpretation? The 10-step systematic approach: 1) Confirm patient details and calibration; 2) Calculate heart rate; 3) Assess rhythm regularity; 4) Identify P waves; 5) Measure PR interval; 6) Assess QRS complex; 7) Examine ST segment; 8) Assess T waves; 9) Measure QTc interval; 10) Determine axis. This systematic approach ensures nothing is missed — always follow the same steps in the same order. ### Q5: What are bad signs on an ECG? Bad signs on ECG requiring urgent attention: **ST elevation** (STEMI until proven otherwise), **new LBBB** in acute chest pain, **wide complex tachycardia** (treat as VT), **complete heart block**, **prolonged QTc > 500ms** (high risk of Torsades), **VT** or **VF**, **ST elevation in aVR** (left main or proximal LAD occlusion), **S1Q3T3** (pulmonary embolism), and **Brugada pattern** (spontaneous coved-type ST elevation in V1-V3). ### Q6: Can an ECG detect a heart blockage? A resting ECG can detect **evidence of old MI** (Q waves) or **acute STEMI** (ST elevation) — both caused by coronary artery blockage. However, it cannot directly visualize the arteries or measure the degree of stenosis. Someone with 80% coronary blockage (stenosis) may have a perfectly normal resting ECG between episodes of ischemia. **Coronary artery disease** (CAD) requires coronary angiography, CT coronary angiography, or stress testing to diagnose and quantify. ### Q7: Can anxiety affect an ECG? Yes — anxiety can affect an ECG: sinus tachycardia (most common — elevated heart rate from sympathetic activation), non-specific ST and T wave changes, premature beats (PACs, PVCs), and hyperventilation-induced T wave changes. A panic attack can produce ECG changes superficially resembling ischemia. The key is clinical context — anxiety-related ECG changes should normalize when the anxiety resolves, unlike true ischemic changes. ### Q8: Do I remove my bra for an ECG? For a 12-lead ECG, **you do not necessarily need to remove a bra** — but the electrodes need to be placed in specific positions on the chest wall. A healthcare professional will ask you to expose your chest and will place electrodes in the correct positions. Underwire bras may need to be removed if they interfere with electrode placement. You will be asked to remove any top clothing covering the chest, and a gown or drape is typically provided for privacy. ### Q9: Does chest hair affect an ECG?** Excessive chest hair can affect ECG quality by reducing electrode-to-skin contact — causing **motion artifact, poor signal quality, and electrode detachment**. If chest hair is causing significant artifact, the area where electrodes are placed may be shaved (with patient consent) to improve contact. Gel electrodes are also used to improve adhesion. For routine 12-lead ECGs, shaving is only done if hair significantly impairs the recording quality. ### Q10: Can I eat before an ECG test?** Yes — eating does not significantly affect a resting 12-lead ECG. You can eat and drink normally before a standard resting ECG. However, for a **stress ECG (exercise test)** or cardiac catheterization, you may be asked to fast. Caffeinated beverages (coffee, energy drinks) should generally be avoided before stress testing. Always follow your specific hospital or clinic instructions. ### Q11: What are the first signs of heart blockage? Symptoms suggesting coronary artery disease (heart blockage): **Chest pain or pressure** (angina) typically with exertion and relieved by rest, **shortness of breath** on exertion, **jaw, arm, or shoulder pain** (referred angina), **fatigue**, and **palpitations**. Acute signs of severe blockage (heart attack): crushing chest pain at rest, severe breathlessness, sweating, nausea, and feeling of impending doom. Seek immediate emergency care for these symptoms. ### Q12: What is the most common abnormal ECG finding? The most common abnormal ECG findings in clinical practice include: **sinus tachycardia** (most common overall — usually a physiological response), **atrial fibrillation** (most common sustained arrhythmia), **non-specific ST/T wave changes**, **left ventricular hypertrophy**, **first-degree heart block**, and **right bundle branch block** (common incidental finding). The most important abnormal findings to identify are STEMI, VT, and complete heart block. ### Q13: When should I worry about my heart? Seek urgent medical attention if you experience: **chest pain** (especially crushing, pressure, or tightness), **chest pain radiating to the arm, jaw, or back**, **sudden shortness of breath**, **sudden palpitations** especially with dizziness or near-fainting, **syncope (fainting)** especially during exercise, **sudden severe headache**, or **5 signs your heart is in danger:** persistent chest discomfort, unexplained fatigue, swollen ankles, rapid unexplained weight gain, and persistent palpitations. Call emergency services (999 in UK, 911 in US) for suspected heart attack symptoms. ### Q14: What is the next step after an abnormal ECG? The next step depends on the specific abnormality: **Acute STEMI:** immediate cath lab activation for primary PCI; **NSTEMI/unstable angina:** urgent inpatient management, troponins, and coronary angiography; **Complete heart block:** emergency pacing; **New arrhythmia:** rhythm-specific management; **Non-specific changes:** repeat ECG, troponin testing, stress ECG, echocardiography, or cardiology referral depending on clinical context. An ECG is rarely the final investigation — it guides the next steps. ### Q15: What is 100% heart blockage? A "100% blockage" of a coronary artery (total occlusion) causes a **STEMI** (ST-Elevation Myocardial Infarction) when it occurs acutely — myocardial cells are dying from lack of blood supply. If the occlusion is chronic and developed slowly, collateral blood vessels may have formed, potentially reducing myocardial damage. "100% blockage" as terminology comes from coronary angiography findings — the gold standard for coronary artery assessment. --- ## Conclusion Whether you came looking for an **ECG quiz with answers PDF**, an **ECG quiz for beginners**, an **ECG nursing quiz**, an **ECG quiz for medical students**, an **ECG interpretation quiz**, or an **ECG multiple choice quiz** — this page has delivered the most complete free ECG quiz resource available online. > **Reminder:** This article is for educational purposes only. ECG interpretation in clinical practice requires hands-on training, supervised experience, and clinical context. Always defer to clinical expertise and established protocols for patient care decisions. **Here is what this page delivered:** - ✅ **25 ECG basics quiz questions** — what ECG is, normal values, waves, and clinical significance - ✅ **20 ECG interpretation quiz questions** — the 10-step systematic approach - ✅ **20 rhythms and arrhythmias questions** — AF, VT, VF, SVT, TdP, hyperkalemia - ✅ **20 12-lead ECG questions** — lead positions, STEMI territories, reciprocal changes, STEMI criteria - ✅ **15 heart block questions** — first, second, third degree, BBB, paced rhythms - ✅ **15 ECG for beginners questions** — foundational concepts with learning tips - ✅ **20 multiple choice questions** — with correct answers marked - ✅ **15 FAQs** — answering every ECG question people search for **Want to create your own interactive ECG quiz for your nursing students or medical team?** 👉 **[Visit DocToQuiz.com](https://doctoquiz.com)** — upload your ECG study materials, lecture notes, or clinical guidelines, let AI generate quiz questions automatically, and share with your students via link or QR code. 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