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ECG (Electrocardiogram) - Sampoorn Guide: Sabhi Heart Diseases ke Saath

ECG Ki Basic Terminology Pehle Samjho

• Speed: 25 mm/sec (standard)
• 1 small box = 0.04 sec (horizontal) / 0.1 mV (vertical)
• 1 large box = 0.2 sec / 0.5 mV

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AV Block (Heart Block) ECG Findings

1st Degree AV Block

• ECG Finding: PR interval >200 ms (>1 large box), sabhi P waves conduct - koi dropped beat nahi
• Mechanism: AV node me delay, conduction interrupt nahi hoti
• Clinical: Usually benign, treatment generally nahi chahiye

2nd Degree AV Block - Mobitz I (Wenckebach)

• ECG Findings:
  • PR interval progressive prolongation (badta jaata hai) - beat by beat
  • RR interval progressively shortens
  • Phir ek QRS drop hoti hai (P wave ke baad QRS missing)
  • "Group beating" pattern (grouped QRS complexes)
• Location: AV node level - benign, pacing usually unnecessary
• Trick: "Longer, longer, longer... DROP! Then Wenckebach"

2nd Degree AV Block - Mobitz II

• ECG Findings:
  • PR interval fixed/constant before dropped beat (koi progressive change nahi)
  • Achanak ek QRS abruptly drops without warning
  • Often associated with wide QRS (bundle branch block)
• Location: Infranodal (His-Purkinje) - dangerous! Permanent pacing required
• Risk: Sudden progression to complete heart block

2:1 AV Block

• ECG: Har 2 P waves me se sirf 1 conducts (ratio 2:1)
• Mobitz I vs II differentiate karna mushkil hota hai
• Clue for Mobitz II: Wide QRS + bundle branch block

3rd Degree (Complete) Heart Block

• ECG Findings:
  • Complete AV dissociation - P waves aur QRS complex bilkul independent
  • P rate > Ventricular rate (atria tez, ventricles dheere)
  • Ventricular rate: ~30-45/min (jidhar se escape rhythm aaye)
  • Wide QRS = infranodal block; Narrow QRS = junctional escape
• Emergency: Pacing required!

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2. Myocardial Infarction (Heart Attack) ECG

ECG Evolution in STEMI (Stages):

Stage 1 (Minutes):     Hyperacute T waves (tall, peaked, broad-based)
Stage 2 (Hours):       ST elevation develops (convex upward / "tombstone")
Stage 3 (Days):        Q waves form + ST elevation persists
Stage 4 (Weeks):       ST normalizes, T wave inversion
Stage 5 (Months):      Persistent Q waves (permanent scar)

Location-Wise ECG Findings in MI

Culprit Artery Identification (ECG se)

Posterior MI (Tricky Case)

• Standard leads me ST depression in V1-V3 dikhta hai (mirror image)
• Tall broad R in V1 (>0.04 sec), R/S ratio ≥1
• Posterior leads V7-V9 lagao: ST elevation >0.5 mm confirm karta hai

Right Ventricular MI

• Always suspect jab inferior MI ho
• Right-sided leads lagao (V4R, V5R, V6R)
• ST elevation ≥1 mm in V4R = diagnostic

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3. Arrhythmias - ECG Findings

Atrial Fibrillation (AF)

• ECG Findings:
  • No visible P waves (replaced by irregular fibrillatory baseline - "f" waves)
  • Irregularly irregular RR intervals
  • QRS usually narrow (unless aberrant conduction)
  • Rate: Ventricular rate typically 100-180/min (uncontrolled)
• Remember: "Totally chaotic, no P, irregular irregular"

Atrial Flutter

• ECG Findings:
  • Sawtooth/picket fence pattern - "F" waves at 250-350/min
  • Classically 2:1 block - ventricular rate ~150/min
  • Best seen in leads II, III, aVF (inferior leads)
  • Regular ventricular rate
• Trick: HR of exactly 150/min = always think flutter

Ventricular Tachycardia (VT)

• ECG Findings:
  • Wide QRS complexes (>0.12 sec) at rate >100/min
  • AV dissociation (P waves independent of QRS)
  • Fusion beats (diagnostic)
  • Capture beats (sinus beat "captures" ventricle - narrow QRS appears)
  • Concordance in precordial leads (all positive or all negative)
• Brugada criteria help differentiate VT from SVT with aberrancy

Ventricular Fibrillation (VF)

• ECG: Completely chaotic irregular waveforms, no identifiable QRS
• Emergency: Immediate defibrillation required!

Wolff-Parkinson-White (WPW) Syndrome

• ECG Findings:
  • Short PR interval (<0.12 sec) - accessory pathway bypasses AV node
  • Delta wave - slurred upstroke of QRS (initial slow conduction via accessory pathway)
  • Wide QRS (>0.12 sec) - fusion of delta + normal conduction
  • Secondary ST-T changes (discordant to QRS)
• Risk: AF with rapid ventricular response (life-threatening)
• Leads: Delta waves best in V1-V6 depending on pathway location

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4. Bundle Branch Blocks

Left Bundle Branch Block (LBBB)

• ECG Findings (William mnemonic - W-i-L-L-i-A-M):
  • V1: Deep broad W pattern (rS or QS)
  • V5/V6: Broad notched M pattern (monophasic R)
  • QRS duration >120 ms
  • ST depression + T inversion in lateral leads (V5, V6, I, aVL)
  • No septal Q waves in lateral leads
• Clinical significance: New LBBB in chest pain = treat like STEMI (Sgarbossa criteria apply)

Right Bundle Branch Block (RBBB)

• ECG Findings (mnemonic - MaRRoW):
  • V1: RSR' pattern = "bunny ears" / M pattern (broad R')
  • V5/V6: Wide S wave (terminal broad S)
  • QRS duration >120 ms
  • ST depression + T inversion in V1-V3 (right precordial leads)
• Clinical: Can be normal variant; may indicate right heart strain or pulmonary disease

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5. Hypertrophy Patterns

Left Ventricular Hypertrophy (LVH)

• Sokolow-Lyon Criteria (most common exam criteria):
  • S in V1 + R in V5 (or V6) ≥35 mm
  • R in aVL ≥11 mm
• Cornell Criteria: S in V3 + R in aVL >28 mm (men) / >20 mm (women)
• Associated findings: Left axis deviation, ST depression + T inversion in I, aVL, V5-V6 ("strain pattern")
• Cause: Hypertension (most common), aortic stenosis

Right Ventricular Hypertrophy (RVH)

• ECG Findings:
  • R/S ratio >1 in V1 (dominant R in V1)
  • Deep S in V5-V6
  • Right axis deviation (>+110°)
  • ST depression + T inversion in V1-V3 (right ventricular strain)
  • P pulmonale: Tall peaked P in II >2.5 mm (if cor pulmonale)
• Cause: COPD, pulmonary hypertension, mitral stenosis

Left Atrial Enlargement (LAE)

• P mitrale: Broad, notched P wave in lead II (>0.12 sec)
• Negative terminal deflection in V1 (>0.04 sec, >1 mm deep)
• Cause: Mitral stenosis, mitral regurgitation

Right Atrial Enlargement (RAE)

• P pulmonale: Peaked P wave in II, III, aVF >2.5 mm tall
• P wave in V1: Prominent initial positive component
• Cause: COPD, tricuspid disease, pulmonary stenosis

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6. Pericarditis ECG

Acute Pericarditis - 4 Stages:

• Diffuse ST elevation (not localized to one territory) - in ALL leads except aVR and V1
• Concave/saddle shaped ST elevation (vs convex in MI)
• PR segment depression (very specific for pericarditis)
• No reciprocal ST depression (unlike MI)
• No Q waves (unlike MI)
• Spodick's sign: Downsloping TP segment in II

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7. Pulmonary Embolism (PE) ECG

• Most common finding: Sinus tachycardia (non-specific but common)
• Classic finding: S1Q3T3 pattern
  • Large S wave in lead I
  • Q wave in lead III
  • T wave inversion in lead III
• Other findings:
  • Right axis deviation
  • RBBB (new - indicates right heart strain)
  • T wave inversion in V1-V4 (right ventricular strain)
  • Sinus tachycardia
  • McGinn-White sign = S1Q3T3 + RBBB
• Note: S1Q3T3 is classic but only present in ~20% cases - sinus tachycardia is more common

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8. Electrolyte Abnormalities ECG

Hyperkalemia (K+ raised)

K+ 5.5-6.5:    Peaked, tall, narrow T waves (tent-shaped)
K+ 6.5-7.5:    Widened QRS, prolonged PR
K+ 7.5-8.0:    P wave disappears (sino-ventricular rhythm)
K+ >8.0:       Sine wave pattern → VF → asystole

Hypokalemia (K+ low)

• U wave prominent (wave after T wave, best in V2-V3)
• Flattened/inverted T wave
• Prolonged QU interval
• PR prolongation
• ST depression

Hypercalcemia

• Short QT interval (QTc <350 ms)
• Short ST segment

Hypocalcemia

• Prolonged QT interval (QTc >450 ms in men, >470 ms in women)
• Long flat ST segment

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9. Other Important ECG Patterns

Long QT Syndrome

• QTc >450 ms (men), >470 ms (women)
• Risk of Torsades de Pointes (TdP) - VT with twisting QRS axis
• Causes: Congenital, drugs (quinidine, haloperidol, erythromycin), electrolyte abnormalities

Brugada Syndrome

• Type 1 (diagnostic): Coved/downsloping ST elevation ≥2 mm in V1-V2, with RBBB morphology
• Type 2: "Saddleback" ST elevation in V1-V2
• Risk: Sudden cardiac death, VF
• May be unmasked by fever, sodium channel blockers, cocaine

Digoxin Toxicity ECG

• "Scooped"/reverse tick ST depression (Salvador Dali mustache)
• PR prolongation (AV block)
• Increased AV block degree
• Bidirectional VT (pathognomonic of severe toxicity)
• Atrial tachycardia with AV block

Cardiac Tamponade

• Electrical alternans: Beat-to-beat alternation in QRS amplitude (heart swinging in pericardial fluid)
• Low voltage QRS throughout
• Sinus tachycardia

Hypothermia ECG

• Osborn (J) waves - distinctive hump at J point, best in lateral leads
• Bradycardia
• Prolonged PR, QRS, QT intervals
• Shivering artifact
• Can progress to VF

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10. Normal ECG Axis

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Quick Revision Table: ECG Findings at a Glance

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🫀 ECG Sampoorn Guide - Sabhi Heart Diseases (Marked & Explained in Hinglish)

📥 Download Links - Saare ECG Diagrams

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📌 DIAGRAM 1 - NORMAL ECG (Samajhne ki shuruat yahan se)

Har Wave kya hoti hai:

Trick: ECG paper - 1 small box = 0.04 sec | 1 large box = 0.2 sec | Standard speed = 25 mm/sec

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📌 DIAGRAM 2 - INFERIOR STEMI (RCA Occlusion)

Marked Findings:

• Leads II, III, aVF mein ST Elevation (convex/dome-shaped upward) = myocardial injury
• Deep Q waves = dead tissue / necrosis = permanent scar
• Hyperacute T waves = bahut early sign (minutes mein)
• Leads V1-V4 mein Reciprocal ST Depression = mirror image of injury area

Location Table (Tintinalli's Emergency Medicine se):

Important: Inferior MI dekho to HAMESHA right-sided leads lagao (V4R) - RV infarct rule out karna zaroori hai!

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📌 DIAGRAM 3 - ANTERIOR STEMI - 3 Stages (LAD Occlusion)

Marked 3 Stages:

• Tall, peaked, broad-based T waves in V1-V4
• Ye sabse pehli sign hai - often miss ho jaati hai!

• Convex (tombstone/dome shaped) ST elevation in V1-V4
• Isoelectric line se upar uthta hai = INJURY

• Deep Q wave (>0.04 sec, >25% of R height) = necrosis/scar
• T wave inversion = repolarization abnormality
• Q waves permanently rehti hain = "old MI" sign

Clinical Pearl: New LBBB + chest pain = treat karo jaise STEMI!

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📌 DIAGRAM 4 - AV BLOCKS - Sabhi 4 Types

Type A - 1st Degree AV Block:

• PR interval >200 ms (1 large box se zyada)
• Koi dropped beat NAHI - sab conduct hoti hai
• Benign - treatment usually nahi chahiye

Type B - 2nd Degree Mobitz I (Wenckebach):

• PR interval progressively badhta jaata hai beat by beat
• RR interval progressively shortens (beats close aate jaate hain)
• Phir achanak ek QRS drop ho jaati hai (P wave ke baad QRS missing)
• "Group beating" pattern
• Trick: "Longer... Longer... Longer... DROP! - Then Wenckebach"
• Location: AV node - relatively benign, usually pacing nahi chahiye

Type C - 2nd Degree Mobitz II:

• PR interval bilkul FIXED rehta hai (koi badlav nahi)
• Phir ACHANAK ek QRS drop ho jaati hai without any warning
• Often wide QRS + bundle branch block saath mein
• DANGEROUS - infranodal location - permanent pacing required even without symptoms!

Type D - 3rd Degree (Complete) Heart Block:

• Complete AV Dissociation - P waves aur QRS bilkul independent
• P waves alag rate pe (e.g., 75/min) | QRS alag rate pe (e.g., 35/min)
• P waves aur QRS ka koi rishta nahi
• Wide QRS = infranodal escape; Narrow QRS = junctional escape
• EMERGENCY - Pacing required immediately!

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📌 DIAGRAM 5 - ATRIAL FIBRILLATION vs ATRIAL FLUTTER

Atrial Fibrillation (AF):

• No P waves - instead chaotic fibrillatory baseline ("f" waves)
• Irregularly irregular QRS - koi pattern nahi, bilkul random
• QRS usually narrow (unless aberrant conduction)
• Trick: "Totally chaotic, no P, irregular-irregular"

Atrial Flutter:

• Sawtooth / Picket fence flutter waves (F waves) at 250-350/min
• Classically 2:1 block → ventricular rate ~150/min
• QRS regular (unlike AF)
• Best seen in leads II, III, aVF (inferior leads)
• Trick: "HR exactly 150/min = ALWAYS think Atrial Flutter first!"

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📌 DIAGRAM 6 - VT & VF (Life-Threatening!)

Ventricular Tachycardia (VT):

• Wide QRS complexes (>0.12 sec) at rate >100/min
• AV dissociation - P waves aur QRS independent (marked with arrows)
• Fusion beats - sinus beat + VT beat merge = diagnostic!
• Capture beats - occasionally sinus captures ventricle = narrow QRS appears
• Bizarre, monophasic QRS morphology
• Onset hone se pehle normal beats dikhtein hain (diagram mein marked)

Ventricular Fibrillation (VF):

• Completely chaotic, irregular waveforms - koi QRS identify nahi ho sakta
• No P wave, no T wave, no nothing
• = Zero cardiac output = Death in minutes
• IMMEDIATE DEFIBRILLATION - CPR shuru karo!

VT vs SVT differentiation: AV dissociation ya fusion beats dikhe → VT confirm! Age >50 + history of MI → VT zyada likely.

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📌 DIAGRAM 7 - BUNDLE BRANCH BLOCKS

LBBB - Mnemonic: "WiLLiaM"

• V1: W pattern (deep QS / rS - no R wave)
• V5/V6: M pattern (broad, notched, bifid R wave)
• QRS >120 ms (>3 small boxes)
• ST depression + T inversion in lateral leads (discordant changes)
• No septal Q waves in lateral leads
• Clinical: New LBBB in chest pain = treat like STEMI! (Sgarbossa criteria)

RBBB - Mnemonic: "MaRRoW"

• V1: RSR' pattern = "Bunny Ears" / M shape (two humps - R' taller)
• V5/V6: W pattern = broad deep S wave (terminal S)
• QRS >120 ms
• ST depression + T inversion in V1-V3 only
• Can be normal variant; also seen in PE, RV strain, ASD

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📌 DIAGRAM 8 - WPW SYNDROME

Pre-excitation Triad (Teen Signs):

1. Short PR interval (<0.12 sec / <3 small boxes)
   • Accessory pathway AV node ko bypass karta hai - isliye signal jaldi pahunchta hai
2. Delta wave - QRS ke shuruat mein slurred (dheerey se utha hua) upstroke
   • Accessory pathway se slowly ventricles activate hote hain pehle
3. Wide QRS (>0.12 sec)
   • Normal + accessory pathway se dono conduction = fusion beat = wide QRS

Danger:

• AF + WPW = Very rapid ventricular rate → VF → death!
• AV nodal blockers (adenosine, verapamil, digoxin) CONTRAINDICATED in WPW + AF
• Treatment: Procainamide, cardioversion, ablation

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📌 DIAGRAM 9 - PERICARDITIS vs STEMI

Pericarditis ECG - Kaise Identify Karein:

4 Stages of Pericarditis:

• Stage I: Diffuse concave ST↑ + PR depression (days 1-2)
• Stage II: ST normalizes, T waves flatten (1-2 weeks)
• Stage III: Diffuse T wave inversion
• Stage IV: ECG normalizes

Spodick's sign = Downsloping TP segment in lead II = specific for pericarditis

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📌 DIAGRAM 10 - ELECTROLYTE DISTURBANCES

Hyperkalemia (K+ Badhna) - ECG Progression:

K+ 5.5-6.5:   Peaked (tent-shaped) T waves → EARLIEST sign!
K+ 6.5-7.5:   Widened QRS, PR prolongation, P wave flattens
K+ 7.5-8.0:   P wave disappears (sinoventricular rhythm)
K+ >8.0:      SINE WAVE pattern → VF → Asystole

• Peaked T wave: Narrow base, tall height, tent shape
• Sine wave: QRS aur T wave merge ho jaati hain - EMERGENCY!

Hypokalemia (K+ Ghatna):

• Prominent U wave (T wave ke baad ek extra hump - best in V2-V3)
• Flat/inverted T waves
• Prolonged QU interval
• PR prolongation, ST depression

Hypercalcemia:

• Short QT interval (QTc <350 ms)

Hypocalcemia:

• Prolonged QT interval (QTc >450 ms men, >470 ms women)

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📌 DIAGRAM 11 - VENTRICULAR HYPERTROPHY

LVH (Left Ventricular Hypertrophy):

• Sokolow-Lyon Criteria (exam standard):
  • S in V1 + R in V5 (or V6) ≥ 35 mm (7 large boxes)
• Cornell Criteria: S-V3 + R-aVL >28 mm (men) / >20 mm (women)
• Strain pattern: Asymmetric ST depression + T inversion in I, aVL, V5-V6
• Left axis deviation
• Cause: Hypertension (commonest), Aortic Stenosis

RVH (Right Ventricular Hypertrophy):

• Dominant R in V1 (R/S ratio >1 in V1)
• Deep S waves in V5-V6
• Right axis deviation (>+110°)
• T inversion in V1-V3 (RV strain)
• P pulmonale: Tall peaked P in II >2.5 mm (RA enlargement)
• Cause: COPD, Pulmonary Hypertension, Mitral Stenosis

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📌 DIAGRAM 12 - Special Patterns (Long QT, Brugada, Hypothermia)

Long QT Syndrome:

• QTc >450 ms (men) / >470 ms (women)
• Long flat ST segment with late T wave
• Risk: Torsades de Pointes (TdP) → VF → sudden death
• Causes: Congenital (Romano-Ward), Drugs (quinidine, haloperidol, erythromycin, methadone), hypokalemia, hypomagnesemia

Brugada Syndrome (Type 1 - Diagnostic):

• V1-V2 mein RSR' (RBBB morphology)
• Coved ST elevation ≥2 mm - peak ke baad downsloping (not saddleback)
• Followed by T wave inversion
• Risk: Sudden VF, nocturnal death
• Unmasked by: Fever, sodium channel blockers, cocaine
• Type 2: Saddleback ST (not diagnostic alone)

Hypothermia - Osborn (J) Waves:

• Osborn / J wave = positive hump at J point (QRS aur ST ke junction par)
• Best seen in lateral leads (V5, V6)
• Bradycardia + prolonged PR + prolonged QRS + prolonged QT
• Shivering artifact bhi dikh sakta hai
• Severe hypothermia (<28°C) → VF

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📌 Ek Aur Important Pattern - Pulmonary Embolism (PE)

S1Q3T3 Pattern:

• S wave in Lead I (large, terminal)
• Q wave in Lead III
• T wave inversion in Lead III
• • New RBBB (right heart strain se)
• • Sinus tachycardia (most common - 94% cases)
• • T inversion in V1-V4

Important: S1Q3T3 only ~20% cases mein hota hai. Sinus tachycardia is the most common finding. RBBB + tachycardia + clinical suspicion → PE consider karo.

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🔥 QUICK REVISION TABLE - Exam ke liye

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📥 Download - Individual Diagrams

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