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EXPLAIN ME 10 COMMON HEART DISEASE WITH ECG CHANGES AND ECG IMAGES OF THOSE DISEASE

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10 common heart diseases ECG changes electrocardiogram findings

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ECG images atrial fibrillation ventricular hypertrophy heart block WPW syndrome pulmonary embolism

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ECG atrial fibrillation irregularly irregular no P waves example image

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ECG complete heart block third degree ventricular hypertrophy WPW delta wave pulmonary embolism S1Q3T3 images

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ECG LVH left ventricular hypertrophy voltage criteria image AND heart failure ECG low voltage

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10 Common Heart Diseases: ECG Changes with Images

1. ST-Elevation Myocardial Infarction (STEMI)

Pathophysiology: Complete occlusion of a coronary artery causes transmural ischemia with immediate electrical changes.
ECG Changes:
  • ST-segment elevation ≥1 mm in two contiguous leads (the defining feature)
  • Hyperacute T waves (tall, broad, peaked) in the earliest minutes
  • Pathologic Q waves (>40 ms wide, >25% QRS height) developing within 8-12 hours - mark irreversible necrosis
  • Reciprocal ST depression in leads opposite to the infarct zone
  • Lead-based localization (from Rosen's Emergency Medicine):
LocationLeads with ST Elevation
Anterior STEMIV1-V4
Lateral STEMII, aVL, V5, V6
Inferior STEMIII, III, aVF
Right ventricular AMIV4R
Posterior AMIV8, V9 (or V1-V3 depression)
ECG Image - Anterolateral STEMI (ST elevation in V2-V6, I, aVL; in-stent thrombosis):
Anterolateral STEMI with ST elevation in V2-V6, I, aVL
Fig: Anterolateral ST segment elevation myocardial infarction (STEMI). STE is seen in V2-V6, I, and aVL. Patient had in-stent thrombosis of the LAD. - Rosen's Emergency Medicine
ECG Image - Inferior STEMI with ST elevation in II, III, aVF and right ventricular involvement in V1:
Inferior STEMI with ST elevation in II, III, aVF and V1
Fig: Inferior STEMI from right coronary artery (RCA) occlusion. Note ST elevation in leads II, III, aVF, and V1 (right ventricular involvement). - Tintinalli's Emergency Medicine

2. Non-ST-Elevation Myocardial Infarction / Unstable Angina (NSTEMI/UA)

Pathophysiology: Partial coronary occlusion causing subendocardial ischemia without full-thickness necrosis.
ECG Changes:
  • ST depression ≥0.5 mm in two or more contiguous leads (most common pattern)
  • T-wave inversion - symmetric, deep inversions (particularly V1-V4 in Wellens' syndrome = critical LAD stenosis)
  • Transient ST changes that may normalize between pain episodes
  • Pseudonormalization of a previously inverted T wave during ischemia
  • No pathologic Q waves and no ST elevation (by definition)
  • A completely normal ECG does NOT exclude NSTEMI - troponins are essential
Wellens' Pattern (critical LAD stenosis):
  • Type A: biphasic T waves in V2-V3
  • Type B: deeply inverted symmetric T waves in V2-V3 (more specific, ~75% sensitivity)
ECG Image - NSTEMI/ACS with Widespread ST Depression and aVR Elevation:
ST depression with aVR elevation suggesting left main disease
Fig: ST elevation in lead aVR with widespread ST depression - a pattern suggesting left main coronary artery disease or proximal LAD occlusion. - Tintinalli's Emergency Medicine

3. Atrial Fibrillation (AF)

Pathophysiology: Chaotic electrical activity in the atria replaces organized P waves with fibrillatory impulses; the AV node conducts irregularly.
ECG Changes (from Tintinalli's Emergency Medicine, Table 18-8):
  • Absence of discernible P waves - replaced by chaotic fibrillatory baseline (f-waves at 350-600/min)
  • Irregularly irregular ventricular rhythm - the hallmark finding, no pattern to R-R intervals
  • Narrow QRS complexes (unless pre-existing bundle branch block or WPW)
  • Ventricular rate typically 110-140 bpm in uncontrolled AF
  • If conducted via accessory pathway (WPW + AF): wide, bizarre, irregular QRS at very rapid rates (>200 bpm) - life-threatening
ECG Image - Atrial Fibrillation:
Atrial fibrillation with irregularly irregular rhythm and no P waves
Fig: Atrial fibrillation (top strip) - note absent P waves, chaotic baseline, and irregularly irregular QRS complexes. Compared with atrial flutter (middle) and multifocal atrial tachycardia (bottom). - Healio / Learn the Heart

4. Acute Pericarditis

Pathophysiology: Inflammation of the pericardium causes diffuse epicardial injury, producing characteristic widespread ECG changes that evolve through 4 stages.
ECG Changes - 4 Stages (from Fuster and Hurst's The Heart):
  • Stage 1 (hours-days): Diffuse ST-segment elevation (concave/saddle-shaped) in ALL leads except aVR and V1 + PR-segment depression (very specific finding) - ST elevation in aVR is opposite
  • Stage 2 (days): ST and PR normalize
  • Stage 3 (1-3 weeks): Diffuse T-wave inversions
  • Stage 4 (weeks-months): ECG returns to baseline
Key distinctions from STEMI:
  • ST elevation is diffuse (not territory-specific)
  • Concave rather than convex ST morphology
  • PR depression is characteristic (rarely seen in STEMI)
  • No reciprocal ST depression (except aVR)
  • No Q waves
ECG Image - Acute Pericarditis (Stage 1):
Acute pericarditis ECG with diffuse ST elevation and PR depression
Fig: Stage 1 acute pericarditis. Diffuse ST-segment elevation with PR-segment depression in a non-territory-specific distribution. Note ST depression with PR elevation in aVR (reciprocal). - Fuster and Hurst's The Heart, 15th Ed.

5. Left Ventricular Hypertrophy (LVH)

Pathophysiology: Chronic pressure overload (hypertension, aortic stenosis) or volume overload increases LV muscle mass, increasing electrical voltage and altering repolarization.
ECG Changes:
  • Increased QRS voltage (the primary feature):
    • Sokolow-Lyon criterion: S in V1 + R in V5 or V6 >35 mm
    • Cornell criterion: R in aVL + S in V3 >28 mm (men) or >20 mm (women)
    • R in aVL >11-12 mm alone (modified Cornell)
  • Left axis deviation (LAD)
  • Prolonged QRS duration (up to 120 ms)
  • LV strain pattern - ST depression and T-wave inversion in left-sided leads (I, aVL, V5, V6), representing secondary repolarization abnormality
  • Left atrial enlargement - broad, notched P wave (P mitrale) in lead II; biphasic P in V1
ECG Image - Severe LVH with Strain Pattern:
LVH with extreme voltages and lateral ST depression strain pattern
Fig: Severe LVH - note extremely tall R waves in V5 and deep S waves in V2 meeting Sokolow-Lyon criteria, with ST depression/T-inversion in lateral leads (strain pattern). - LITFL ECG Library

6. Complete (Third-Degree) AV Heart Block

Pathophysiology: No conduction passes from atria to ventricles. The atria and ventricles beat independently from separate pacemakers.
ECG Changes:
  • Complete AV dissociation - P waves and QRS complexes are completely independent (P waves march through at their own rate, QRS at a slower escape rate)
  • Regular P-P interval (normal atrial rate, 60-100 bpm)
  • Regular R-R interval (escape rhythm, bradycardic)
  • Escape QRS morphology:
    • Junctional escape (narrow QRS, rate ~40-60 bpm) if block is at AV node
    • Ventricular escape (wide, bizarre QRS, rate ~20-40 bpm) if block is below the His bundle - more dangerous
  • No relationship between P waves and QRS - P waves may fall before, within, or after QRS
  • Causes: inferior MI (often transient), Lyme carditis, digoxin toxicity, idiopathic fibrosis
ECG Image - Inferior STEMI with AV Block (showing dissociation pattern):
Inferior STEMI with AV conduction abnormality
Fig: Inferior-lateral MI from left circumflex artery occlusion - ST elevation in II, III, aVF, and V2 with ST depression in V1-V3 (reciprocal). Inferior MIs can be complicated by AV block due to RCA/AV nodal artery compromise. - Tintinalli's Emergency Medicine

7. Wolff-Parkinson-White (WPW) Syndrome

Pathophysiology: An accessory pathway (Bundle of Kent) bypasses the AV node, pre-exciting part of the ventricle before the normal conduction system depolarizes the rest. This creates a characteristic ECG pattern.
ECG Changes:
  • Short PR interval <120 ms (bypasses AV node delay)
  • Delta wave - slurred, slow upstroke at the start of the QRS (initial pre-excitation of ventricle via accessory pathway)
  • Wide QRS (>120 ms) due to fusion of accessory pathway and normal conduction
  • Discordant ST-T changes - ST depression and T-wave inversions opposite to the delta wave direction
  • WPW Type A (left-sided pathway): dominant R in V1, resembles RVH
  • WPW Type B (right-sided pathway): negative delta/QRS in V1, resembles LBBB
  • During AF with WPW: extremely rapid, irregular, wide-complex tachycardia >200 bpm - treat as an emergency (avoid AV nodal blockers like adenosine/verapamil)
Key point: The delta wave can mimic STEMI (pseudo-delta waves in certain leads) and can also mask true infarction.

8. Pulmonary Embolism (PE)

Pathophysiology: Massive PE causes acute right ventricular pressure overload and strain, producing distinctive but non-specific ECG changes.
ECG Changes:
  • Sinus tachycardia - most common finding (found in ~40% of PE cases)
  • S1Q3T3 pattern (McGinn-White sign): Deep S wave in lead I + Q wave in lead III + inverted T wave in lead III - classic but seen in only ~20%
  • Right heart strain pattern: T-wave inversions in V1-V4 (anterior leads)
  • Right bundle branch block (RBBB) - complete or incomplete - due to acute RV dilation
  • Right axis deviation
  • Atrial fibrillation or flutter
  • Clockwise rotation of the heart (S waves in V5-V6)
  • Note: ECG can be completely normal in up to 20% of PE cases
ECG Image - Anterior STEMI for comparison with PE (which can also show V1-V4 changes):
The pericarditis ECG above (diffuse ST elevation + PR depression) illustrates how PE-related ST changes can be confused with other diagnoses. Below is the anterolateral STEMI ECG for comparison with the V-lead changes seen in PE:
Anterior STEMI ECG showing V-lead changes for PE comparison
Note: In PE, the T-wave inversions are primarily in V1-V4 (right-sided strain), while anterior STEMI shows ST elevation in V1-V4. The key distinction: PE gives T inversions in V1-V4; STEMI gives ST elevation.

9. Dilated Cardiomyopathy / Congestive Heart Failure

Pathophysiology: Ventricular dilation and dysfunction alter conduction, causing diffuse myocardial changes on ECG.
ECG Changes:
  • Left bundle branch block (LBBB) - very common (broad, notched QRS >120 ms; dominant negative in V1; dominant positive in V5-V6; no septal Q waves in I/V5-V6)
  • Sinus tachycardia at rest (elevated sympathetic tone)
  • Non-specific ST-T changes and T-wave flattening
  • LVH voltage criteria (if hypertensive cardiomyopathy)
  • Low-voltage QRS (<5 mm in limb leads, <10 mm in precordial leads) - suggests pericardial effusion or infiltrative disease (amyloid)
  • Prolonged QRS/QTc - risk of ventricular arrhythmias and sudden death
  • Atrial fibrillation is very common (20-30% of HF patients)
  • Premature ventricular contractions (PVCs) - common
  • First-degree AV block - PR >200 ms
ECG Image - Serial ACS/HF ECG Showing Evolution:
Serial ECG showing STEMI evolution in a patient with acute chest pain
Fig: This ECG demonstrates how acute MI - a common cause of new-onset cardiomyopathy - shows evolving changes including ST deviation and left-sided involvement. Dilated cardiomyopathy may show LBBB, low voltage, or persistent ST-T changes from prior infarcts.

10. Atrial Flutter

Pathophysiology: A macro-reentrant circuit in the right atrium (usually around the tricuspid annulus) causes rapid, regular atrial depolarization at ~300 bpm, with AV conduction at a fixed ratio.
ECG Changes:
  • Flutter waves ("F-waves") - classic "sawtooth" or "picket fence" pattern at ~300 bpm
  • Most visible in leads II, III, aVF, and V1 (inferior leads are best)
  • Regular atrial rate ~300 bpm (240-340 bpm)
  • Fixed AV block ratio:
    • 2:1 block - ventricular rate ~150 bpm (most common)
    • 3:1 block - ventricular rate ~100 bpm
    • 4:1 block - ventricular rate ~75 bpm
  • Regular ventricular rhythm (unless variable block)
  • Narrow QRS unless aberrant conduction
  • Tip: At a ventricular rate of exactly 150 bpm, always suspect flutter with 2:1 block - flutter waves may be hidden in T waves
ECG Image - Atrial Flutter:
Atrial flutter with sawtooth flutter waves and AV block
Fig: A. Regular narrow tachycardia at ~155 bpm. B. Full 12-lead showing classic sawtooth flutter waves in leads II, III, and aVF. C. Response to carotid sinus massage - transient AV block unmasks flutter waves clearly. - Tintinalli's Emergency Medicine

Quick Summary Table

#ConditionKey ECG FindingRateRhythm
1STEMIST elevation in contiguous leads + Q wavesNormal-fastRegular
2NSTEMI/UAST depression, T-wave inversionNormalRegular
3Atrial FibrillationNo P waves, irregularly irregularVariableIrregular
4Acute PericarditisDiffuse ST elevation + PR depressionNormalRegular
5LVHHigh voltage + lateral strainNormalRegular
6Complete Heart BlockAV dissociation, bradycardiaSlow escapeRegular (AV dissociated)
7WPW SyndromeShort PR + delta wave + wide QRSVariableVariable
8Pulmonary EmbolismS1Q3T3, sinus tach, V1-V4 T inversionsFastRegular
9Dilated CMP/CHFLBBB, low voltage, AF, PVCsVariableVariable
10Atrial FlutterSawtooth F-waves at ~300 bpm, 2:1 block~150 bpmRegular
Sources: Rosen's Emergency Medicine, Tintinalli's Emergency Medicine, Fuster and Hurst's The Heart (15th Ed.), Goldman-Cecil Medicine, Harrison's Principles of Internal Medicine 22E, LITFL ECG Library
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