Ecg changes common 10
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Here are the 10 Common ECG Changes you need to know, compiled from Harrison's, Washington Manual, Rosen's Emergency Medicine, and Comprehensive Clinical Nephrology:
10 Common ECG Changes
1. 🫀 Acute STEMI (ST-Elevation Myocardial Infarction)
Classic evolutionary sequence:
- Hyperacute T waves (peaked, earliest change)
- ST-segment elevation (>1 mm) in ≥2 contiguous leads
- Pathological Q waves (≥0.04 s wide, ≥0.1 mV deep) — develop within hours to days
- T-wave inversion (later phase)
- New LBBB = STEMI equivalent
Swanson's Family Medicine Review
2. 💔 NSTEMI / Unstable Angina (Subendocardial Ischemia)
- ST depression in concordant leads
- T-wave inversion (without Q waves)
- May be normal or nonspecific
Rosen's Emergency Medicine
3. ⚡ Hyperkalemia
Progressive changes with rising K⁺:
| K⁺ (mmol/L) | ECG Change |
|---|---|
| 6–7 | Peaked (tented) T waves |
| 7–8 | Flattened P waves, prolonged PR, depressed ST |
| 8–9 | Atrial standstill, wide QRS |
| >9 | Sine-wave pattern → VF → asystole |
Comprehensive Clinical Nephrology, 7th Ed.
4. 🔋 Hypokalemia
- Flattened/inverted T waves
- Prominent U waves (hallmark)
- Depressed ST segment
- Prolonged QU interval (looks like QT prolongation)
- Delayed depolarization
Harrison's Principles of Internal Medicine, 22E
5. 🫁 Pulmonary Embolism (PE)
- S1Q3T3 pattern: Deep S in lead I, Q wave + T-wave inversion in lead III (classic but insensitive)
- RV strain: T-wave inversion in V1–V4
- Sinus tachycardia (most common finding)
- Right axis deviation, RBBB (acute cor pulmonale)
Rosen's Emergency Medicine
6. 💧 Pericarditis
- Diffuse (saddle-shaped) ST elevation in most leads (except aVR, V1 — which show ST depression)
- PR-segment depression (very specific sign)
- Electrical alternans → suggests pericardial effusion/tamponade
Rosen's Emergency Medicine; Washington Manual
7. 🧂 Hypocalcemia
- Prolonged QT interval (specifically the ST/QTc portion is extended)
- Predisposes to Torsades de Pointes
8. 🧂 Hypercalcemia
- Shortened QT interval
- May shorten ST segment
Harrison's Principles of Internal Medicine, 22E
9. 💊 Digitalis Effect / Toxicity
- "Scooped" ST-T wave (sagging ST depression — the "Salvador Dalí moustache" sign) = therapeutic effect
- Toxicity: PAT with block, bidirectional VT, PVCs, AV blocks
- Shortens QT interval
Harrison's Principles of Internal Medicine, 22E
10. 🌡️ Hypothermia
- Osborn wave (J wave): Characteristic convex hump at the J point, best seen in V5–V6 and leads II/aVF
- Bradycardia
- Prolonged PR, QRS, QT intervals
- Shivering artifact
- Risk of VF at core temperature <30°C
Harrison's Principles of Internal Medicine, 22E
Bonus Summary Table
| Condition | Key ECG Finding |
|---|---|
| STEMI | ST elevation, hyperacute T, Q waves |
| NSTEMI/UA | ST depression, T inversion |
| Hyperkalemia | Peaked T → sine wave |
| Hypokalemia | Prominent U waves, flat T |
| PE | S1Q3T3, RV strain, tachycardia |
| Pericarditis | Diffuse ST↑, PR depression |
| Hypocalcemia | Long QT |
| Hypercalcemia | Short QT |
| Digitalis | Scooped ST, short QT |
| Hypothermia | Osborn (J) wave, bradycardia |
Quick memory tip:
"STEMI peaks early, Peri-PR drops, K+ tents then sines, Hypo-Ca stretches QT, Hypo-K shows U, PE strains the right, Dig scoops, Hypo-therm Osborns"
Each ecg explain with images of ecg and markings
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STEMI ST elevation myocardial infarction ECG 12 lead
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hyperkalemia peaked T waves sine wave ECG changes
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pericarditis diffuse ST elevation PR depression ECG
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hypokalemia U wave flat T wave ECG
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pulmonary embolism S1Q3T3 right ventricular strain ECG
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hypothermia Osborn J wave ECG bradycardia
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NSTEMI ST depression T wave inversion subendocardial ischemia ECG
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digitalis effect scooped ST depression ECG digoxin toxicity
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hypocalcemia prolonged QT interval ECG hypercalcemia short QT
Here are all 10 Common ECG Changes with Images and Markings:
📊 10 Common ECG Changes — With Images
1. 🔴 STEMI (ST-Elevation Myocardial Infarction)
What to look for (markings):
| Finding | Location | Significance |
|---|---|---|
| ▲ ST elevation (convex/tombstone) | V1–V6 (anterior), II/III/aVF (inferior) | Acute injury = STEMI |
| ▲ Hyperacute T waves (tall, peaked, broad-based) | Same leads as STE | Earliest sign |
| ▼ Reciprocal ST depression | Opposite leads (e.g., II/III/aVF if anterior) | Confirms STEMI |
| Q waves (wide ≥0.04s, deep ≥0.1mV) | Infarcted territory | Necrosis |
| New LBBB | All leads | STEMI equivalent |
🔑 Rule: ST elevation >1 mm in ≥2 contiguous leads. New LBBB = automatic cath lab activation.
2. 🟠 NSTEMI / Unstable Angina (Subendocardial Ischemia)
What to look for:
| Finding | Description |
|---|---|
| ▼ Horizontal/downsloping ST depression | ≥0.5 mm; most specific for ischemia |
| T-wave inversion (deep, symmetric) | Subendocardial or Wellens pattern |
| No Q waves | Differentiates from STEMI |
| May be normal | High-risk feature: troponin rise confirms |
🔑 Key: ST depression (not elevation). Troponin + = NSTEMI; Troponin − = Unstable Angina.
3. 🟡 Hyperkalemia
Peaked (tented) T waves with blue arrow annotations at K⁺ = 7.3 mmol/L
Progressive stages: Mild-Moderate → Moderate-Severe → Very Severe sine wave (Harrison's)
Sequential ECG changes:
| K⁺ Level | ECG Finding |
|---|---|
| 6–7 mmol/L | 🔺 Tall, narrow-based, peaked (tented) T waves |
| 7–8 mmol/L | Flat P waves, ↑PR interval, depressed ST |
| 8–9 mmol/L | Absent P waves (atrial standstill), wide QRS |
| >9 mmol/L | Sine wave pattern → VF → Asystole |
🔑 Memory: "The K+ rises, T peaks, P flattens, QRS widens, then sine-wave = EMERGENCY"
4. 🟢 Hypokalemia
Hallmark: flattened T waves + prominent U waves (V3–V6), "camel-hump" morphology
What to look for:
| Finding | Description |
|---|---|
| Flat/inverted T waves | Most prominent in lateral leads (I, V4–V6) |
| ▲ Prominent U wave (positive hump after T) | Best seen V2–V4; U > T amplitude = severe |
| "Camel-hump" T-U fusion | Looks like prolonged QT — actually QU interval |
| ST depression | Mild, diffuse |
🔑 U waves are the hallmark. Best seen in V2–V3. If U wave > T wave → K⁺ likely <2.5 mEq/L.
5. 🫁 Pulmonary Embolism (PE)
Classic S1Q3T3 pattern with labeled arrows + T-wave inversions V1–V6 (RV strain)
What to look for:
| Finding | Lead | Significance |
|---|---|---|
| S1 – deep S wave | Lead I | Right axis deviation |
| Q3 – Q wave | Lead III | RV strain |
| T3 – inverted T | Lead III | RV strain |
| T-wave inversions | V1–V4 | Anterior RV strain |
| Sinus tachycardia | All | Most common finding overall |
| Incomplete/complete RBBB | V1 rSR' | Acute cor pulmonale |
| Right axis deviation | Frontal | RV overload |
🔑 S1Q3T3 = classic but only present in ~20% of PE. Sinus tachycardia + RV strain pattern is more sensitive.
6. 💧 Pericarditis
Diffuse concave "saddle-shaped" ST elevation + PR depression in lead II + Spodick's sign
What to look for:
| Finding | Description |
|---|---|
| Diffuse concave (saddle-shaped) ST elevation | Nearly all leads except aVR, V1 |
| PR depression (most specific sign) | Lead II, V4–V6; PR elevation in aVR |
| Spodick's sign | Downsloping TP segment |
| Electrical alternans | Alternating QRS voltage = pericardial effusion/tamponade |
| NO reciprocal ST depression | Distinguishes from STEMI |
🔑 Pericarditis vs STEMI: Diffuse (not regional) ST↑, PR depression, concave (not convex) shape, no reciprocal changes.
7. 🧂 Hypocalcemia + Hypercalcemia (Combined)
Panel C (Hypocalcemia): Long ST segment → long QT. Panel D (Hypercalcemia): Short ST → short QT
QT = 0.48s, QTc = 0.51 in hypocalcemia (Harrison's)
Hypocalcemia:
| Finding | Description |
|---|---|
| ↑ QT interval (specifically ST segment prolonged) | T wave unchanged; ST is lengthened |
| Risk of Torsades de Pointes | Polymorphic VT if QTc >500 ms |
Hypercalcemia:
| Finding | Description |
|---|---|
| ↓ Short QT interval | ST segment abbreviated |
| Short/absent ST segment | T wave sits close to QRS |
🔑 Ca²⁺ and QT: Low Ca = Long QT. High Ca = Short QT. Think: "Calcium Controls the ST segment length."
8. 💊 Digitalis Effect / Toxicity
Atrial fibrillation + classic "scooped" down-sloping ST depression V4–V6 (digoxin effect)
Therapeutic Effect vs Toxicity:
| State | ECG Finding |
|---|---|
| Digoxin effect (therapeutic) | "Scooped" / Salvador Dalí moustache ST depression, short QT |
| Toxicity | PVCs/bigeminy, PAT with block, AV blocks (2°/3°), bidirectional VT |
🔑 "Scooped" ST depression = digoxin effect (normal/therapeutic). PVCs + AV block = toxicity.
9. 🌡️ Hypothermia
A = Sinus bradycardia. C = Osborn (J) wave hump at J-point in V5. B = T-wave inversions.
What to look for:
| Finding | Description |
|---|---|
| Osborn (J) wave | Convex hump at J-point (between QRS and ST); best in V5–V6, II/aVF |
| Sinus bradycardia | Most common rhythm |
| ↑ PR, QRS, QT intervals | All intervals prolonged |
| Shivering artifact | Baseline tremor on tracing |
| VF risk | Core temp <30°C |
🔑 Osborn wave = pathognomonic of hypothermia. Size of J wave inversely proportional to core temperature.
10. 📈 Hyperkalemia Pretreatment vs Post-Treatment
Panel A: K⁺ = 9.25 mEq/L — peaked T, wide QRS, absent P, sine wave. Panel B: After treatment — normal P waves, narrow QRS, normal T waves restored.
🗺️ Quick Visual Summary
| # | Condition | Key ECG Feature | Best Lead to See It |
|---|---|---|---|
| 1 | STEMI | ST elevation (convex) + Q waves | V1–V6 / II,III,aVF |
| 2 | NSTEMI | ST depression + T inversion | Ischemic territory |
| 3 | Hyperkalemia | Peaked T → sine wave | V2–V3 |
| 4 | Hypokalemia | U waves + flat T | V2–V4 |
| 5 | PE | S1Q3T3 + RV strain | I, III, V1–V4 |
| 6 | Pericarditis | Diffuse ST↑ + PR depression | Lead II, all leads |
| 7 | Hypocalcemia | Long QT (ST lengthened) | V2–V5 |
| 8 | Hypercalcemia | Short QT | V2–V5 |
| 9 | Digitalis | Scooped ST depression | V4–V6 |
| 10 | Hypothermia | Osborn (J) wave | V5–V6, II |
Sources: Harrison's Principles of Internal Medicine 22E, Rosen's Emergency Medicine, Comprehensive Clinical Nephrology 7th Ed, Washington Manual of Medical Therapeutics
Treatment for hyperaemia
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