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ECG findings 10 cardiac diseases STEMI atrial fibrillation heart block WPW hyperkalemia pericarditis images

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ECG pericarditis hyperkalemia WPW long QT Brugada ventricular tachycardia images site:litfl.com OR site:ecgwaves.com

Here is your comprehensive guide to 10 diseases and their characteristic ECG findings, with textbook images.

ECG Findings in 10 Diseases

1. Anterolateral ST-Elevation Myocardial Infarction (STEMI)

ECG Features:

ST elevation in leads V1-V4 (anterior) and I, aVL, V5-V6 (lateral)
Reciprocal ST depression in inferior leads (III, aVF)
Hyperacute T waves early; Q waves develop as infarct evolves
Proximal LAD occlusion produces the widest distribution of changes

Anterolateral STEMI - ST elevation V1-V6 and I, aVL

Fig. 1 - Anterolateral STEMI: ST elevation in V1-V4 and leads I, aVL, V5-V6. Proximal LAD lesion confirmed at PCI. (ROSEN's Emergency Medicine)

2. Inferior STEMI

ECG Features:

ST elevation in leads II, III, aVF
Reciprocal ST depression in I and aVL
If ST elevation is greater in lead III than lead II: suggests RCA occlusion (90% sensitive, 71% specific)
ST elevation in V1 with inferior MI suggests right ventricular infarction
Posterior extension: ST depression + tall R waves in V1-V3

Inferior STEMI with reciprocal changes - leads II, III, aVF elevation

Fig. 2 - Inferior STEMI with marked ST elevation in inferior leads and ST depression reciprocal changes in aVL/I. (ROSEN's Emergency Medicine)

3. High Lateral STEMI

ECG Features:

ST elevation in leads I and aVL (first diagonal or left circumflex occlusion)
Reciprocal ST depression in leads III, aVF, and V1
May have subtle ST elevation in V2

High lateral STEMI - ST elevation leads I and aVL

Fig. 3 - High Lateral STEMI: ST elevation I and aVL, reciprocal depression III, aVF. 90% stenosis at LAD/D1 bifurcation. (ROSEN's Emergency Medicine)

4. Extensive Inferior + Posterior + RV MI (15-Lead ECG)

ECG Features:

ST elevation II, III, aVF (inferior)
ST depression V1-V3 with prominent R wave = posterior MI (reciprocal)
ST elevation in posterior leads V8-V9
ST elevation in right-sided leads (RVq) = right ventricular MI

15-lead ECG inferior lateral posterior and RV MI

Fig. 4 - 15-lead ECG showing inferior + lateral + posterior + RV infarction. Note posterior leads V8-V9 and right-sided leads (ROSEN's Emergency Medicine)

5. Atrial Fibrillation (AF)

ECG Features:

No discernible P waves - replaced by chaotic/fibrillatory baseline
Irregularly irregular ventricular response
Narrow QRS complexes (unless bundle branch block/preexcitation coexists)
Atrial rate >600 bpm; ventricular rate typically 120-170 bpm when AV node unaffected
A very rapid ventricular response (>200 bpm) suggests an accessory pathway (WPW)

Atrial fibrillation - three examples showing irregularly irregular rhythm and no P waves

Fig. 5 - Three examples of atrial fibrillation showing absence of P waves and irregularly irregular ventricular response. (Tintinalli's Emergency Medicine)

6. Atrial Flutter

ECG Features:

Regular "sawtooth" flutter waves at ~300 bpm - best seen in II, III, aVF, V1
Usually regular ventricular rate due to fixed AV block ratio (2:1 most common = ~150 bpm)
Regular narrow-complex tachycardia at exactly ~150 bpm should always raise suspicion for flutter with 2:1 block
P waves (flutter waves) are single morphology, downward-deflecting

7. Ventricular Tachycardia (VT)

ECG Features:

Wide-complex tachycardia (QRS >120 ms, often >160 ms)
AV dissociation (P waves and QRS complexes independent) - most reliable sign of VT
Fusion beats and capture beats confirm AV dissociation
Concordance: all precordial leads positive (positive concordance) or all negative (negative concordance) - strongly suggests VT
No RS complex in any precordial lead favors VT
Initial R wave in aVR favors VT

Key rule: Any wide-complex tachycardia should be treated as VT until proven otherwise, especially in patients with structural heart disease or prior MI.

8. Third-Degree (Complete) AV Block

ECG Features:

Complete dissociation of P waves and QRS complexes
Atrial rate is faster than ventricular rate
P waves march through at their own rate; QRS complexes at a slow escape rate (20-60 bpm)
Wide QRS escape rhythm = block below AV node (His-Purkinje); narrow QRS = junctional escape
Causes: acute MI (especially inferior), Lyme disease, autoimmune, infiltrative cardiomyopathy, drug toxicity

Key finding: Regular P waves at ~80 bpm + slow regular wide QRS at ~35 bpm, completely independent of each other.

9. Wolff-Parkinson-White (WPW) Syndrome

ECG Features:

Short PR interval (<120 ms)
Delta wave - slurred upstroke at start of QRS due to ventricular preexcitation
Widened QRS (>120 ms)
Pseudo-ST and T changes (secondary repolarization abnormalities)
Risk: AF with rapid conduction through accessory pathway can precipitate VF

Classic triad: Short PR + delta wave + widened QRS = WPW pattern.

10. Hyperkalemia

ECG Features (progressive with rising K+):

K+ Level	ECG Change
5.5-6.0 mEq/L	Tall, peaked (tented) T waves - narrow base, symmetric
6.0-7.0 mEq/L	PR prolongation, P wave flattening
7.0-8.0 mEq/L	Widening of QRS
>8.0 mEq/L	Sine wave pattern (QRS merges with T wave)
Critical	Ventricular fibrillation / asystole

Peaked T waves in hyperkalemia are narrow-based and symmetric, distinguishing them from the broad asymmetric T waves in ischemia.

Summary Table

#	Disease	Key ECG Finding
1	Anterolateral STEMI	ST elevation V1-V4, I, aVL
2	Inferior STEMI	ST elevation II, III, aVF + reciprocal changes
3	High Lateral STEMI	ST elevation I, aVL
4	Posterior/RV MI	ST depression V1-V3 + tall R, ST elevation V8-V9/RV leads
5	Atrial Fibrillation	No P waves, irregularly irregular QRS
6	Atrial Flutter	Sawtooth flutter waves ~300 bpm, regular ventricular rate ~150
7	Ventricular Tachycardia	Wide QRS, AV dissociation, fusion beats
8	Complete Heart Block	P-QRS dissociation, atrial rate > ventricular rate
9	WPW Syndrome	Short PR, delta wave, wide QRS
10	Hyperkalemia	Peaked T waves → wide QRS → sine wave pattern

*Sources: ROSEN's Emergency Medicine (9th Ed.), Tintinalli's Emergency Medicine, Braunwald's Heart Disease, Goldman-Cecil Medicine, Harrison's Principles of Internal Medicine 22E (2025)*This covers 10 important conditions with their hallmark ECG patterns and real textbook ECG images. Here are a few high-yield mnemonics to remember:

STEMI localization: ST elevation in II/III/aVF = inferior; V1-V4 = anterior; I/aVL = lateral; V1-V3 depression + tall R = posterior
AF vs Flutter: AF = irregularly irregular + no P waves; Flutter = regular sawtooth at 300 bpm with 2:1 block giving rate ~150
VT vs SVT: Wide complex + AV dissociation + fusion beats = VT until proven otherwise
WPW triad: Short PR + delta wave + wide QRS
Hyperkalemia progression: Peaked T → flat P → wide QRS → sine wave → VF

Let me know if you'd like to go deeper on any specific condition!

ECG finding with images and ECG reading with all disease.

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Complete ECG Guide: Findings & Readings Across All Major Diseases

HOW TO READ ANY ECG - Systematic Approach

Before reading individual diseases, always follow this order:

Rate - Count R waves in 6-second strip x 10, or 300/large squares between R-R
Rhythm - Regular? Irregular? Identify P waves
P waves - Present? Normal shape? One before each QRS?
PR interval - Normal: 120-200 ms (3-5 small squares)
QRS duration - Normal: <120 ms (3 small squares)
QRS axis - Normal: -30° to +90°
ST segments - Elevation? Depression? Horizontal/upsloping/downsloping?
T waves - Upright? Inverted? Peaked?
QT interval - QTc normal: <440 ms (male), <460 ms (female)
Ancillary - Q waves, bundle branch blocks, hypertrophy

SECTION A: ISCHEMIC HEART DISEASE

1. Anterior STEMI (LAD Occlusion)

ECG Reading:

Feature	Finding
Rate	Usually normal or tachycardic
Rhythm	Sinus rhythm (may have PVCs)
P waves	Normal
PR interval	Normal
QRS	May develop pathological Q waves in V1-V4
ST segments	Elevation in V1-V4 (and I, aVL if anterolateral)
T waves	Hyperacute upright early; inversion later
Reciprocal	ST depression in II, III, aVF

Key ECG findings:

ST elevation ≥1 mm in 2 contiguous leads
"Tombstone" ST elevations in severe LAD occlusion
Loss of R-wave progression (R waves become smaller V1→V4)
Pathological Q waves (>1 small sq wide, >¼ R-wave height) = completed infarct

Anterolateral STEMI - ST elevation V1-V4, I, aVL with Q waves forming

ECG: Anterolateral STEMI. ST elevation clearly visible in V1-V4 and lateral leads I, aVL, V5-V6. Proximal LAD occlusion. (ROSEN's Emergency Medicine)

2. Inferior STEMI (RCA or LCx Occlusion)

ECG Reading:

Feature	Finding
ST Elevation	II, III, aVF
Reciprocal	ST depression in I, aVL
Key clue	If STE greater in III than II → RCA occlusion (90% sens.)
RV involvement	STE in V1 with inferior MI = right ventricular MI
Posterior extension	ST depression + tall R in V1-V3

How to distinguish RCA vs LCx inferior STEMI:

RCA: STE III > II, ST depression in aVL and I
LCx: STE II ≥ III, aVL isoelectric or elevated

Inferior STEMI with reciprocal ST depression in I and aVL

ECG: Inferior STEMI. Marked ST elevation in II, III, aVF with reciprocal ST depression in aVL and lateral leads. (ROSEN's Emergency Medicine)

3. High Lateral STEMI (Diagonal / LCx Occlusion)

ECG Reading:

Feature	Finding
ST Elevation	I, aVL (sometimes V2)
Reciprocal	ST depression in III, aVF, V1
Culprit	First diagonal (D1) or left circumflex

High lateral STEMI - ST elevation leads I and aVL with reciprocal ST depression

ECG: High Lateral STEMI. ST elevation in I, aVL. Reciprocal depression in III, aVF, V1. (ROSEN's Emergency Medicine)

4. Extensive Inferior + Posterior + Right Ventricular MI

ECG Reading (15-lead):

Territory	Leads	Finding
Inferior	II, III, aVF	ST elevation
Lateral	I, aVL, V5-V6	ST elevation
Posterior	V1-V3 (standard)	ST depression + tall R wave (reciprocal)
Posterior (direct)	V7-V9	ST elevation (smaller magnitude)
Right ventricle	RV4	ST elevation

Reading tip: Posterior MI is the "mirror image" - flip V1-V3 upside down mentally and you see STEMI pattern.

15-lead ECG: Inferior, posterior, lateral, and right ventricular MI all in one tracing

ECG: 15-lead showing inferior + lateral + posterior + RV MI. Standard leads show inferior STE; V1-V3 show STD with prominent R (posterior); V8-V9 and RVq confirm. (ROSEN's Emergency Medicine)

SECTION B: ARRHYTHMIAS

5. Atrial Fibrillation (AF)

ECG Reading:

Feature	Finding
Rate	Ventricular: 120-170 bpm (uncontrolled); slower if controlled/AV node disease
Rhythm	Irregularly IRREGULAR - hallmark
P waves	ABSENT - replaced by chaotic fibrillatory baseline
PR interval	Not measurable
QRS	Narrow (unless BBB or WPW coexists)
Baseline	Fine fibrillatory waves, most prominent in V1

Key rule: If you see NO P waves + irregularly irregular QRS = AF until proven otherwise.

AF with rate >200 bpm = suspect WPW accessory pathway (medical emergency - avoid AV nodal blockers!)

Three examples of atrial fibrillation showing absent P waves and irregularly irregular QRS complexes

ECG: Three examples of AF. Note the complete absence of P waves, chaotic baseline, and irregularly irregular ventricular response. (Tintinalli's Emergency Medicine)

6. Atrial Flutter

ECG Reading:

Feature	Finding
Rate	Atrial: ~300 bpm; Ventricular: ~150 bpm (2:1 block)
Rhythm	Usually regular (if fixed AV block ratio)
P waves	Sawtooth flutter waves - no isoelectric baseline between them
Best leads	II, III, aVF, V1 for flutter waves
AV ratio	Usually 2:1 (rate ~150), can be 3:1 or 4:1

Bedside clue: Regular narrow-complex tachycardia at exactly ~150 bpm = atrial flutter with 2:1 block until proven otherwise. Apply vagal maneuver to slow rate and reveal flutter waves.

7. Ventricular Tachycardia (VT)

ECG Reading:

Feature	Finding
Rate	100-250 bpm
Rhythm	Usually regular
QRS	Wide (>120 ms), often >160 ms
AV dissociation	P waves and QRS independent - most specific sign
Fusion beats	Hybrid QRS (sinus + VT) = confirms AV dissociation
Capture beats	Narrow QRS "captured" in a run of wide QRS = confirms VT
Concordance	All precordial QRS all positive (positive) or all negative (negative) = strongly suggests VT
aVR sign	Initial R wave in aVR, or notching of initial downstroke = VT

Critical rule: Any wide-complex tachycardia in a patient with prior MI or cardiomyopathy = VT until proven otherwise. Never give verapamil to wide-complex tachycardia.

8. Supraventricular Tachycardia (SVT/AVNRT)

ECG Reading:

Feature	Finding
Rate	150-250 bpm
Rhythm	Perfectly regular
QRS	Narrow (<120 ms) unless aberrant conduction
P waves	Hidden in or just after QRS (retrograde P waves)
RP interval	Very short (<70 ms in AVNRT)
Response	Terminates abruptly with vagal maneuver or adenosine

9. Complete (Third-Degree) AV Heart Block

ECG Reading:

Feature	Finding
P waves	Present, regular at own rate (~60-100 bpm)
QRS	Present, regular at slow escape rate (20-60 bpm)
Key finding	P waves and QRS are COMPLETELY INDEPENDENT
Atrial rate	Always FASTER than ventricular rate
QRS morphology	Narrow = junctional escape; Wide = ventricular escape (worse)

How to read: Measure P-P interval and R-R interval separately. They march out at their own rates with NO relationship to each other.

Complete AV block (High-grade): Sinus P waves at 82 bpm completely dissociated from slow ventricular escape rhythm

ECG: High-grade/Complete AV block. Sinus P waves at ~82 bpm march independently from slow ventricular complexes. Variable R-R confirms intermittent conduction. (Braunwald's Heart Disease)

SECTION C: CONDUCTION DISORDERS

10. Right Bundle Branch Block (RBBB)

ECG Reading:

Feature	Finding
QRS duration	≥120 ms (wide)
V1 pattern	rsR' or rSR' ("rabbit ears") pattern
Wide S wave	Wide terminal S in V5-V6 and lead I
ST/T	Discordant ST/T in V1-V2 (opposite to QRS)
Axis	Usually normal

Memory aid: "WiLLiaM MaRRoW" for LBBB vs RBBB - in V1: LBBB = W shape, RBBB = M shape. In V6: LBBB = M, RBBB = W.

RBBB: rsR' pattern in V1, wide S in V5-V6, normal axis, discordant ST changes

ECG: Right Bundle Branch Block (RBBB). Widened QRS with rsR' in V1, wide terminal S wave in V5 and lead I. (Goldman-Cecil Medicine)

11. Left Bundle Branch Block (LBBB)

ECG Reading:

Feature	Finding
QRS duration	≥120 ms
V1 pattern	QS or rS pattern (deep S, no R)
V5-V6 pattern	Broad notched R wave without Q
Lead I/aVL	Broad notched R wave
ST/T	Discordant throughout (ST/T opposite to QRS)
Clinical significance	New LBBB with chest pain = treat as STEMI equivalent!

Reading LBBB: In V1 you see a deep wide S (or QS); in V6 and I you see a tall notched R. The ST-T changes are EXPECTED (secondary) and should NOT be over-interpreted unless using Sgarbossa criteria.

LBBB (E): Broad notched R in I, aVL, V4-V6; QS in V1-V3; discordant ST-T changes

ECG: Left Bundle Branch Block (LBBB) - Panel E. Broad notched R waves in I, aVL, V4-V6. QS in V1-V3. Discordant ST/T changes throughout. (Goldman-Cecil Medicine)

12. Left Anterior Fascicular Block (LAFB)

ECG Reading:

Feature	Finding
QRS duration	<120 ms (normal width)
Axis	Left axis deviation: -45° to -90°
Lead I, aVL	qR pattern (small Q, tall R)
Lead II, III, aVF	rS pattern (small R, deep S)
Clinical	Often benign; may indicate LAD disease if new

13. RBBB + LAFB (Bifascicular Block)

ECG Reading:

Feature	Finding
QRS duration	≥120 ms
V1	rsR' (RBBB pattern)
Axis	Left axis deviation (-45° to -90°)
Clinical risk	May progress to complete heart block; consider pacing

RBBB + LAFB (C): Wide QRS with rsR' in V1 plus marked left axis deviation (-60°)

ECG: RBBB + Left Anterior Fascicular Block. rsR' pattern in V1 (RBBB) combined with left axis deviation ~-60° (LAFB). (Goldman-Cecil Medicine)

SECTION D: CHANNELOPATHIES & GENETIC SYNDROMES

14. Wolff-Parkinson-White (WPW) Syndrome

ECG Reading (Sinus Rhythm):

Feature	Finding
PR interval	Short (<120 ms)
Delta wave	Slurred upstroke at start of QRS
QRS	Widened (>120 ms)
ST/T	Pseudo-changes (secondary to pre-excitation)
Risk	AF with rapid accessory pathway conduction → VF

Classic ECG triad: Short PR + Delta wave + Wide QRS

During WPW tachycardias:

Orthodromic AVRT (65%): Regular, narrow complex, rate 160-220 bpm
Antidromic AVRT (5-10%): Wide complex, looks like VT
AF with WPW: Irregular, wide-complex, rates >200 bpm (most dangerous!)

Never give: Adenosine, verapamil, digoxin, or beta-blockers in AF + WPW (can cause VF)

WPW Syndrome: Short PR interval, delta waves clearly visible, widened QRS complex

ECG: Wolff-Parkinson-White syndrome. Short PR interval and slurred delta wave upstroke with widened QRS. (Tintinalli's Emergency Medicine)

WPW - Short PR, delta wave, wide QRS; downward arrows mark delta waves in V1

ECG: WPW with delta wave morphology upright in V1 and across precordium, negative in inferior leads - consistent with left posterior accessory pathway. (Braunwald's Heart Disease)

15. Long QT Syndrome

ECG Reading:

Feature	Finding
QTc	>440 ms (male), >460 ms (female) - corrected by Bazett: QTc = QT/√RR
T waves	Broad, notched, or "humped" T waves
Arrhythmia	Torsades de pointes (twisting QRS axis around baseline)
Risk triggers	Hypokalemia, hypomagnesemia, QT-prolonging drugs, exercise

Bazett formula: QTc = QTm ÷ √(R-R interval in seconds)

Normal QT at 60 bpm: 350-440 ms
QTc >500 ms = very high risk for torsades

Causes of acquired long QT:

Drugs: antipsychotics, macrolides, fluoroquinolones, antifungals, sotalol, amiodarone
Electrolytes: hypokalemia, hypomagnesemia, hypocalcemia
Ischemia, CNS events (stroke, SAH)

16. Brugada Syndrome

ECG Reading:

Feature	Finding
Key leads	V1-V2 (and V3)
Type 1 (diagnostic)	Coved ST elevation ≥2 mm with downsloping to negative T wave
Type 2	Saddleback pattern (>2 mm ST elevation, positive or biphasic T)
QRS	May resemble RBBB
Provocation	ST changes worsen with fever, Na+ channel blockers, drugs

Reading Brugada: In V1, look for a "shark fin" or "coved" pattern - the ST goes up, curves over, and descends to a negative T wave. This is NOT normal RBBB.

Clinical: Predominantly affects young males. Risk of polymorphic VT and VF during sleep or fever. Associated with SCN5A loss-of-function mutations. Treatment: ICD.

SECTION E: ELECTROLYTE DISORDERS

17. Hyperkalemia

ECG Reading (Progressive Changes):

K+ Level	ECG Change
5.5-6.0 mEq/L	Tall, peaked (tented) T waves - narrow base, symmetric, pointy
6.0-7.0 mEq/L	PR prolongation, P wave flattening/disappearance
7.0-8.0 mEq/L	Progressive QRS widening
>8.0 mEq/L	Sine wave pattern (QRS merges with T wave)
Critical	VF or asystole

Peaked T waves in hyperkalemia vs ischemia:

Hyperkalemia: Narrow base, symmetric, tall, pointy ("tented")
Ischemia (hyperacute): Broad base, asymmetric, usually in one territory

Hyperkalemia can also mimic:

Brugada pattern (pseudo-RBBB + coved ST in V1-V2)
STEMI pattern (especially when QRS widens)

18. Hypokalemia

ECG Reading:

Feature	Finding
T waves	Flattened or inverted T waves
U waves	Prominent U waves (after T wave, especially V2-V3)
QT interval	Apparent QT prolongation (actually QU prolongation)
ST changes	ST depression
Risk	Torsades de pointes

Key sign: Prominent U wave (positive deflection after T wave) larger than T wave in same lead = hypokalemia until proven otherwise.

SECTION F: PERICARDIAL & MYOCARDIAL DISEASE

19. Acute Pericarditis

ECG Reading (4 Stages):

Stage 1 (Hours to days - diagnostic stage):

Feature	Finding
ST elevation	Diffuse, concave (saddle-shaped), in MULTIPLE territories
PR depression	Diffuse PR depression (most leads)
aVR	ST depression + PR ELEVATION ("knuckle sign")
Key distinction	NO reciprocal ST depression (unlike STEMI)

Stage 2 (Days): ST and PR normalize

Stage 3 (1-3 weeks): Diffuse T-wave inversions

Stage 4 (Weeks-months): ECG returns to normal

Pericarditis vs STEMI:

Feature	Pericarditis	STEMI
ST distribution	Diffuse (multiple territories)	Localized (one territory)
ST shape	Concave (saddle-shaped)	Convex (domed/tombstone)
PR depression	YES (hallmark)	NO
Reciprocal changes	ABSENT	PRESENT
Q waves	NO	YES (infarct)

Acute Pericarditis - Stage 1: Diffuse saddle-shaped ST elevation with PR depression across multiple leads

ECG: Acute Pericarditis Stage 1. Diffuse ST elevation in non-territory-specific distribution, PR depression in most leads, PR elevation in aVR. (Fuster & Hurst's The Heart)

20. Hypertrophic Cardiomyopathy (HCM)

ECG Reading:

Feature	Finding
LVH voltage	Tall R in V5-V6 (>26 mm), tall R in aVL (>13 mm)
Pathological Q waves	Deep, narrow Q waves in I, aVL, V5-V6 (septal hypertrophy)
T waves	Deep T-wave inversions (especially lateral)
ST changes	ST depression in lateral leads
Apical HCM	Giant T-wave inversions (deeply negative, "giant negative T waves") in V4-V6

SECTION G: PULMONARY DISEASE

21. Pulmonary Embolism (PE)

ECG Reading:

Feature	Finding
Most common	Sinus tachycardia (most frequent finding)
S1Q3T3	S wave in I + Q wave in III + T-wave inversion in III
Right heart strain	T-wave inversions V1-V4 (right precordial)
RBBB	New incomplete or complete RBBB
Right axis deviation	QRS axis shifts rightward
P pulmonale	Tall peaked P waves in II (right atrial enlargement)

Caution: S1Q3T3 is specific but not sensitive (seen in <20% of PE). Most PE ECGs show only sinus tachycardia or are normal. The most specific finding for massive PE is new RBBB + right precordial T-wave inversions.

22. Chronic Obstructive Pulmonary Disease (COPD) / Cor Pulmonale

ECG Reading:

Feature	Finding
Rate/rhythm	Sinus tachycardia; Multifocal atrial tachycardia (MAT) in COPD exacerbations
P pulmonale	Tall peaked P waves in II, III, aVF (>2.5 mm)
Right axis deviation	QRS axis +90° to +180°
Poor R progression	Small R waves across precordium (low voltage)
RVH pattern	R > S in V1, deep S in V5-V6
Low voltage	QRS <5 mm limb leads (air trapping/barrel chest)

MAT (Multifocal Atrial Tachycardia): Rate >100 bpm, ≥3 different P-wave morphologies, irregular rhythm - classic in COPD/respiratory failure.

SECTION H: STRUCTURAL HEART DISEASE

23. Left Ventricular Hypertrophy (LVH)

ECG Reading:

Feature	Finding
Cornell criteria	S in V3 + R in aVL >2.8 mV (men), >2.0 mV (women)
Sokolow-Lyon	S in V1 + R in V5 or V6 >35 mm
"Strain pattern"	ST depression + T inversion in I, aVL, V5-V6
Left axis deviation	Mild LAD common

24. Right Ventricular Hypertrophy (RVH)

ECG Reading:

Feature	Finding
R > S in V1	Dominant R in V1 (R wave taller than S wave)
Right axis deviation	Axis >+90°
Deep S in V5-V6	Persistence of S waves laterally
ST/T changes	Strain pattern: ST depression + T inversion in V1-V3

SECTION I: OTHER IMPORTANT ECG PATTERNS

25. Digoxin Effect vs Digoxin Toxicity

Digoxin Effect (therapeutic):

Feature	Finding
ST changes	"Scooped" or reversed tick ST depression - characteristic downsloping
QT	Shortened
PR	Mildly prolonged
T waves	Flattened or inverted

Digoxin Toxicity:

Feature	Finding
Bradycardia	SA or AV node dysfunction
Heart blocks	1st, 2nd, or 3rd degree AV block
Atrial tachycardia with block	Classic: PAT with 2:1 block
Bidirectional VT	Alternating QRS axis - pathognomonic
Ventricular arrhythmias	PVCs, bigeminy, VT, VF

26. Hypercalcemia vs Hypocalcemia

Condition	ECG Finding
Hypercalcemia	Shortened QT interval (shortened ST segment)
Hypocalcemia	Prolonged QT interval (prolonged ST segment, QT >500 ms)

27. Early Repolarization (Benign)

ECG Reading:

Feature	Finding
J point	Notched or slurred J point at QRS-ST junction
ST shape	Upsloping/concave ST elevation
Distribution	Mid-lateral precordial leads, can be inferior
aVR	Reciprocal ST depression in aVR
Common in	Young males, athletes (up to 100% in endurance athletes)

Distinguish from pericarditis: Early repolarization has no PR depression, no evolution through stages, and changes normalize with exercise/tachycardia.

28. Hypothermia

ECG Reading:

Feature	Finding
Rate	Bradycardia (profound)
Osborn (J) wave	Positive deflection at J point - pathognomonic for hypothermia
QRS	Widening
QT	Prolonged
Arrhythmia	AF, VF at <28°C core temperature
Muscle tremor	Fine artifact simulating AF

Summary Quick-Reference Table

#	Disease	Rate	Rhythm	Key ECG Finding
1	Anterior STEMI	Normal/↑	Sinus	STE V1-V4, Q waves developing
2	Inferior STEMI	Normal/↑	Sinus	STE II, III, aVF + reciprocal STD I, aVL
3	High Lateral STEMI	Normal/↑	Sinus	STE I, aVL + reciprocal STD III, aVF
4	Posterior MI	Normal	Sinus	STD V1-V3 + tall R wave, STE V7-V9
5	Atrial Fibrillation	Variable	Irregularly irregular	No P waves, chaotic baseline
6	Atrial Flutter	~150	Regular	Sawtooth flutter waves at 300 bpm
7	Ventricular Tachycardia	100-250	Regular	Wide QRS + AV dissociation
8	SVT/AVNRT	150-250	Regular	Narrow QRS, P hidden in QRS
9	Complete Heart Block	Slow escape <40	AV dissociated	Independent P waves and QRS
10	RBBB	Normal	Sinus	rSR' in V1, wide S in V5-V6
11	LBBB	Normal	Sinus	Broad notched R in I, V5-V6; QS in V1
12	LAFB	Normal	Sinus	Left axis deviation, qR in aVL
13	WPW	Variable	Variable	Short PR + delta wave + wide QRS
14	Long QT	Normal	Sinus (risk of TdP)	QTc >440-460 ms, broad T waves
15	Brugada	Normal	Sinus (risk of VF)	Coved ST elevation V1-V2, negative T
16	Hyperkalemia	Slow	Sinus → sinusoidal	Peaked T → flat P → wide QRS → sine wave
17	Hypokalemia	Normal	Sinus (risk of TdP)	Flat T, prominent U wave, long QU
18	Acute Pericarditis	Normal/↑	Sinus	Diffuse STE concave + PR depression
19	PE	↑ (tachycardia)	Sinus	S1Q3T3, T inversion V1-V4, RBBB
20	COPD/Cor Pulmonale	↑	MAT or sinus	P pulmonale, RAD, poor R progression
21	LVH	Normal	Sinus	Voltage criteria + strain pattern
22	Digoxin toxicity	Slow	Various	PAT with block, bidirectional VT
23	Hypothermia	Slow	AF/VF at <28°C	Osborn (J) wave, bradycardia
24	Hypocalcemia	Normal	Sinus (risk of TdP)	Long QT (prolonged ST)

*Sources: ROSEN's Emergency Medicine (9th Ed.), Tintinalli's Emergency Medicine, Braunwald's Heart Disease, Fuster & Hurst's The Heart (15th Ed.), Goldman-Cecil Medicine, Harrison's Principles of Internal Medicine 22E (2025)*This is a full illustrated ECG reference guide covering 24 diseases across 8 clinical categories, with real textbook ECG images. Here's a recap of what's covered:

Sections:

A - Ischemic Heart Disease: Anterior STEMI, Inferior STEMI, High Lateral STEMI, Posterior/RV MI
B - Arrhythmias: AF, Atrial Flutter, VT, SVT, Complete Heart Block
C - Conduction Disorders: RBBB, LBBB, LAFB, Bifascicular block
D - Channelopathies: WPW, Long QT, Brugada syndrome
E - Electrolytes: Hyperkalemia, Hypokalemia
F - Pericardial/Myocardial: Acute Pericarditis, HCM
G - Pulmonary: PE (S1Q3T3), COPD/Cor pulmonale/MAT
H - Structural + Other: LVH, RVH, Digoxin toxicity, Hypothermia (Osborn waves), Hypocalcemia

High-yield memory pearls:

PR depression = pericarditis (no other cause does this diffusely)
Short PR + delta wave = WPW
Peaked T → sine wave = hyperkalemia progression
S1Q3T3 + sinus tach = think PE
Wide QRS + AV dissociation = VT
Irregularly irregular + no P waves = AF

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