Explain 10 common heart diseases with ecg changes and ecg images of those diseases

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I now have an excellent collection of ECG images and clinical data from authoritative textbooks. Let me compile the comprehensive answer with all 10 heart diseases, their ECG changes, and real ECG images from the medical library.

10 Common Heart Diseases: ECG Changes & Images

Here is a detailed guide to 10 common heart diseases, their characteristic ECG findings, and real ECG images sourced from authoritative medical textbooks (Harrison's, Tintinalli's Emergency Medicine, Fuster & Hurst's The Heart, and others).

1. ST-Elevation Myocardial Infarction (STEMI)

What it is: Complete occlusion of a coronary artery causing full-thickness (transmural) myocardial necrosis.

ECG Changes:

Hyperacute T waves - earliest change, tall broad T waves in affected territory
ST-segment elevation - convex ("tombstone") elevation ≥1 mm in limb leads, ≥2 mm in precordial leads, in a territory-specific distribution
Reciprocal ST depression in opposite leads (indicates larger area at risk, higher mortality)
Pathological Q waves - develop within hours, indicate established necrosis (≥40 ms wide, ≥25% depth of R wave)
T-wave inversion - follows ST elevation as infarct evolves

Territory-Specific ECG Localization (from Tintinalli's Emergency Medicine):

Territory	ST Elevation Leads	Culprit Artery
Anterior	V1-V4	LAD (distal)
Anterolateral	V1-V6, I, aVL	LAD (proximal)
Inferior	II, III, aVF	RCA or LCx
Lateral	I, aVL	LCx
Right Ventricular	V3R-V6R	Proximal RCA
Posterior	Tall R in V1-V2, ST depression	LCx or RCA

ECG - Inferior STEMI (right coronary artery occlusion): ST elevation in III > II, with reciprocal ST depression in I and aVL:

Inferior STEMI - ST elevation in inferior leads with RCA occlusion

Inferior STEMI from right coronary artery occlusion. ST-segment elevation in lead III greater than lead II, with ST-segment depression in leads I and aVL. 100% RCA occlusion confirmed at catheterization. - Tintinalli's Emergency Medicine

ECG - Anterior STEMI (LAD occlusion): Marked ST elevation in aVR suggesting left main/proximal LAD occlusion:

Anterior STEMI with aVR elevation suggesting LAD/left main occlusion

ST elevation in aVR > V1, suggesting proximal LAD/left main occlusion. Initial troponin normal; second troponin abnormal. 90% left main occlusion confirmed at catheterization. - Tintinalli's Emergency Medicine

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

What it is: Partial coronary occlusion causing subendocardial ischemia without full-thickness necrosis. NSTEMI is diagnosed by elevated troponin; unstable angina has normal biomarkers.

ECG Changes:

ST-segment depression - horizontal or downsloping ≥0.5 mm in ≥2 contiguous leads
T-wave inversion - symmetric, deep (especially in anterior leads suggests LAD ischemia)
Wellens' syndrome - biphasic or deeply inverted T waves in V2-V3 = critical proximal LAD stenosis; 15% of unstable angina patients
ECG may be normal in up to 6% of NSTEMI patients
No pathological Q waves (no transmural necrosis)

Special Pattern - Wellens' Sign: Deeply inverted T waves in V2-V3 signaling critical LAD stenosis. These patients are at high risk of imminent anterior STEMI and need urgent intervention.

3. Atrial Fibrillation (AF)

What it is: Chaotic disorganized electrical activity in the atria at 350-600 impulses/min. The most common sustained cardiac arrhythmia (affects ~1-2% of the general population).

ECG Changes:

Absent P waves - replaced by irregular fibrillatory baseline (f waves), most visible in V1
Irregularly irregular RR intervals - hallmark finding; no two RR intervals are equal
Variable ventricular rate - depending on AV node conduction (typically 100-180 bpm if untreated)
Narrow QRS complexes (unless aberrant conduction or pre-existing bundle branch block)
Fibrillatory baseline - chaotic, low-amplitude oscillations between QRS complexes

The complete heart block ECG below shows the contrast between organized and disorganized atrial activity. In the image below (from Fuster & Hurst's), note the complete absence of organized P waves with irregular baseline activity characteristic of AF:

Complete heart block with atrial fibrillation - shows irregular atrial activity in V1, with regular ventricular escape in lead II

Atrial fibrillation with complete heart block: V1 (top) shows the irregular fibrillatory baseline without organized P waves characteristic of AF. Lead II (bottom) shows regular, slow ventricular escape rhythm. - Fuster & Hurst's The Heart

4. Atrial Flutter

What it is: A macro-reentrant circuit in the right atrium cycling at 250-300 bpm, typically with 2:1 AV conduction producing a ventricular rate of 125-150 bpm.

ECG Changes:

Sawtooth flutter waves at 250-300 bpm - classic negative sawtooth in leads II, III, aVF; positive in V1
Regular atrial activity at ~300 bpm (more organized than AF)
Regular ventricular rate at 150 bpm with 2:1 block (most common), or 100 bpm with 3:1, or 75 bpm with 4:1 block
Absent isoelectric baseline between flutter waves
QRS complexes are narrow (unless aberrant conduction)
Flutter waves may be hidden within QRS or T waves at 2:1 ratio; adenosine or carotid massage unmasks them

ECG - Typical Atrial Flutter (counterclockwise, Type 1):

Typical atrial flutter showing sawtooth pattern in inferior leads

12-lead ECG of typical (counterclockwise) atrial flutter. Note the sawtooth pattern of atrial activation with negative flutter waves in inferior leads (II, III, aVF) and positive flutter waves in V1. 4:1 AV conduction here makes the flutter waves clearly visible. - Harrison's Principles of Internal Medicine 22E

5. Ventricular Tachycardia (VT)

What it is: A rapid rhythm originating from the ventricular myocardium at ≥3 consecutive beats and a rate of ≥120 bpm. Associated with structural heart disease (prior MI, cardiomyopathy) in the majority of cases.

ECG Changes (Monomorphic VT):

Wide QRS complexes >120 ms with consistent beat-to-beat morphology
Rate 140-180 bpm (range 120-300 bpm), regular rhythm
AV dissociation - P waves bear no relationship to QRS (pathognomonic when seen)
Fusion beats and capture beats - highly specific for VT
Concordance - all QRS complexes positive (positive concordance) or all negative (negative concordance) in V1-V6
Northwest axis (axis between -90° and ±180°) - strongly suggests VT

ECG Changes (Polymorphic VT / Torsades de Pointes):

Varying QRS morphology and amplitude that appears to "twist" around the baseline
Irregular rhythm, rate 140-300 bpm
Associated with prolonged QT interval in sinus rhythm (Torsades de pointes)

ECG - Monomorphic and Polymorphic VT:

Three examples of monomorphic and polymorphic ventricular tachycardia

Three examples of ventricular tachycardia. (A) Monomorphic VT at 270 bpm - rapid regular wide QRS complexes with consistent morphology. (B) Polymorphic VT showing varying QRS morphology and amplitude. (C) Torsades de pointes - the characteristic "twisting of the points" pattern around the isoelectric baseline. - Tintinalli's Emergency Medicine

6. Complete Heart Block (Third-Degree AV Block)

What it is: Complete dissociation between atrial and ventricular electrical activity - no atrial impulses conduct to the ventricles. A ventricular (or junctional) escape rhythm takes over at a slow rate.

ECG Changes:

Complete AV dissociation - P waves and QRS complexes march independently
Regular P-P intervals at normal atrial rate (60-100 bpm)
Regular (but slow) RR intervals from escape rhythm - typically 30-60 bpm for ventricular escape, 40-60 bpm for junctional escape
P rate > QRS rate always
Wide QRS complexes if escape is ventricular in origin (LBBB or RBBB morphology)
Narrow QRS if the escape focus is junctional (above the bundle of His)

ECG - Complete Heart Block with narrow complex escape:

Complete heart block with narrow complex (junctional) escape rhythm

Complete heart block. V1 (top) shows rapid atrial activity. Lead II (bottom) shows slow regular junctional escape rhythm with narrow QRS complexes, completely dissociated from the atrial rate. - Fuster & Hurst's The Heart

ECG - Complete Heart Block with RBBB morphology escape (with His bundle recording):

Complete heart block with wide complex escape and His bundle electrogram showing block below His

Complete heart block with RBBB-morphology escape rhythm. His bundle electrogram (bottom) shows A, H, V activity with block below the His - confirming infra-Hisian block. This carries worse prognosis and typically requires pacemaker implantation. - Fuster & Hurst's The Heart

7. Acute Pericarditis

What it is: Inflammation of the pericardial sac, most commonly viral in etiology, causing subepicardial irritation reflected in widespread ECG changes. Diagnosis requires ≥2 of: typical chest pain, friction rub, ECG changes, and pericardial effusion.

ECG Changes (4-Stage Evolution):

Stage	Timing	ECG Finding
Stage I	Hours to days	Diffuse ST elevation (concave up, non-territory-specific) + PR depression
Stage II	Days	ST normalizes, PR returns to baseline
Stage III	Days to weeks	Diffuse T-wave inversion
Stage IV	Weeks to months	ECG returns to baseline

Key distinguishing features from STEMI:

ST elevation is diffuse (multiple territories - not following one coronary distribution)
ST shape is concave ("saddle-shaped") vs. convex in STEMI
PR depression in multiple leads (especially II, V4-V6) - highly specific for pericarditis
PR elevation in aVR ("knuckle sign")
No reciprocal ST depression (except aVR)
No Q waves
ST:T wave ratio in V6 >0.24 favors pericarditis over early repolarization

ECG - Three stages of acute pericarditis:

Three-stage ECG progression of acute pericarditis

Typical 3-stage evolution of acute pericarditis. (A) Stage I: Diffuse ST-segment elevation and PR depression in leads I, II, III, and aVF. ST:T ratio in V1 = 0.50, confirming pericarditis. (B) Stage II: ST segments returning toward isoelectric. (C) Stage III: Resolution of ST changes with development of diffuse T-wave inversion. - Tintinalli's Emergency Medicine

ECG - Stage I pericarditis (12-lead):

12-lead ECG of Stage I acute pericarditis showing diffuse ST elevation and PR depression

12-lead ECG in Stage I acute pericarditis. Diffuse ST-segment elevation with concordant PR-segment depression in a non-territory-specific distribution. Note simultaneous ST depression with PR elevation in aVR (the "knuckle sign"). - Fuster & Hurst's The Heart, 15th Edition

8. Pulmonary Embolism (PE)

What it is: Obstruction of pulmonary arteries by thrombus (most commonly), causing acute right heart strain. ECG is non-specific; ~20% of PE patients have a normal ECG.

ECG Changes:

Sinus tachycardia - most common finding (seen in ~40% of PE)
S1Q3T3 pattern - S wave in lead I, Q wave and T-wave inversion in lead III (classic but insensitive, ~20%)
Right bundle branch block (RBBB) - new or incomplete; reflects acute RV strain
Right axis deviation
T-wave inversions in V1-V4 - right ventricular strain pattern (most common precordial change)
P pulmonale - peaked P waves in II, III, aVF (right atrial enlargement)
Atrial arrhythmias - AF, atrial flutter in ~20% of cases
ST elevation in V1, ST depression in I and aVL

The ECG shown earlier for pericarditis (Fuster & Hurst block 17, line 804) notes: "Atrial arrhythmias, most frequently atrial fibrillation, may be associated with acute PE. Approximately 20% of patients with PE have no ECG changes."

9. Left Ventricular Hypertrophy (LVH)

What it is: Thickening of the left ventricular myocardium from pressure overload (hypertension, aortic stenosis) or volume overload. A major independent cardiovascular risk factor.

ECG Changes (Voltage Criteria + Strain Pattern):

Increased QRS voltage:
- Sokolow-Lyon: S in V1 + R in V5 or V6 ≥35 mm
- Cornell: R in aVL + S in V3 >28 mm (men), >20 mm (women)
- R in aVL ≥11 mm alone
LV strain pattern - ST depression and T-wave inversion in lateral leads (I, aVL, V5, V6); "strain" pattern is more specific than voltage alone
Left axis deviation (more common in LVH + LBBB)
Prolonged QRS duration approaching but usually <120 ms
Left atrial enlargement - broad notched P wave in II ("P mitrale"), biphasic P in V1 with deep terminal component
Poor R-wave progression in V1-V3

Clinical note: ECG has low sensitivity (~50%) but high specificity (~85-95%) for LVH; echocardiography is the gold standard.

10. Hypertrophic Cardiomyopathy (HCM)

What it is: Genetic disease (usually sarcomere protein mutations) causing asymmetric septal or concentric LV hypertrophy with preserved or hyperdynamic systolic function, diastolic dysfunction, and risk of sudden cardiac death.

ECG Changes:

LVH voltage criteria - typically present (high amplitude QRS)
Deep, narrow ("dagger-shaped") Q waves in lateral leads (I, aVL, V5-V6) and inferior leads - from abnormal septal depolarization; a hallmark finding that can mimic prior MI
ST depression and T-wave inversions in lateral/inferior leads ("strain" pattern)
Giant T-wave inversions in anterior precordial leads (V3-V5) especially in the apical variant (Yamaguchi syndrome)
Left atrial enlargement (common due to elevated LVEDP)
Atrial fibrillation - important complication, develops in 20-25% of HCM patients
WPW-like delta waves can occur in PRKAG2 mutation HCM
Prolonged QRS - less common than in dilated cardiomyopathy

Key distinguishing feature from other LVH: The deep narrow septal Q waves in lateral leads without a history of infarction, combined with voltage criteria and young age, should raise suspicion for HCM.

Summary Table

Disease	Key ECG Finding	Rate	Rhythm
STEMI	ST elevation in territory + reciprocal depression, Q waves	Variable	Regular
NSTEMI/UA	ST depression, T-wave inversion, or normal	Variable	Regular
Atrial Fibrillation	No P waves, irregularly irregular RR	100-180	Irregularly irregular
Atrial Flutter	Sawtooth at 300 bpm, 2:1 block (rate 150)	150 (2:1)	Regular
Ventricular Tachycardia	Wide QRS, AV dissociation, fusion beats	140-300	Regular (monomorphic)
Complete Heart Block	AV dissociation, slow escape, P rate > QRS rate	30-60 escape	Regular (both independent)
Acute Pericarditis	Diffuse concave ST elevation, PR depression	Normal	Regular
Pulmonary Embolism	S1Q3T3, sinus tachy, RBBB, T inversion V1-V4	Tachycardia	Regular
LVH	High voltage, strain pattern V5-V6, aVL	Normal	Regular
HCM	Deep Q waves lateral leads, giant T inversions (apical)	Normal	Regular (until AF)

Sources: Tintinalli's Emergency Medicine (9th Ed.), Fuster and Hurst's The Heart (15th Ed.), Harrison's Principles of Internal Medicine (22nd Ed., 2025), Braunwald's Heart Disease (2-Vol Set).

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