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❤️ HEART - ROBBINS PATHOLOGY

MBBS Exam Prep | Key Topics with Flowcharts

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📌 TOPIC 1: HEART FAILURE (Congestive Heart Failure)

Definition

Heart cannot pump blood to meet metabolic demands of peripheral tissues, OR can do so only at elevated filling pressures.

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PATHOGENESIS FLOWCHART

PRECIPITATING CAUSE
(IHD / Hypertension / Valvular disease / Cardiomyopathy)
            │
            ▼
  ↑ Cardiac workload OR ↓ Contractility
            │
            ▼
   ┌─────────────────────────────────────┐
   │     COMPENSATORY MECHANISMS         │
   │  1. Frank-Starling mechanism        │
   │     (↑ filling → ↑ contraction)     │
   │  2. Neurohumoral activation         │
   │     - ↑ Norepinephrine → ↑HR, ↑CO  │
   │     - ↑ RAAS → Na+/H₂O retention   │
   │     - ↑ ANP → counterbalances RAAS  │
   │  3. Cardiac hypertrophy             │
   └─────────────────────────────────────┘
            │
            ▼ (mechanisms overwhelmed)
   DECOMPENSATION
            │
     ┌──────┴──────┐
     ▼             ▼
SYSTOLIC         DIASTOLIC
DYSFUNCTION      DYSFUNCTION
(↓ EF < 40%)    (Impaired filling)
HFrEF           HFpEF

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TYPES & MORPHOLOGY TABLE

KEY EXAM FACT: Heart failure cells = hemosiderin-laden macrophages in alveoli = sign of previous pulmonary edema (Left CHF)

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📌 TOPIC 2: ISCHEMIC HEART DISEASE (IHD)

OVERVIEW FLOWCHART

RISK FACTORS
├── Non-modifiable: Age, Male sex, Family history
└── Modifiable: Hyperlipidemia, Hypertension, Smoking,
                Diabetes, Obesity, Sedentary lifestyle
            │
            ▼
   CORONARY ATHEROSCLEROSIS (>90% cases)
   (Decades of silent plaque buildup)
            │
            ▼
   PLAQUE RUPTURE / EROSION
            │
            ▼
   THROMBUS FORMATION
            │
     ┌──────┴───────────────────┐
     ▼          ▼               ▼
STABLE       UNSTABLE      COMPLETE
ANGINA       ANGINA        OCCLUSION
(partial,    (50% occlusion (STEMI → MI)
 stable)      + thrombus)

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4 CLINICAL PRESENTATIONS OF IHD

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MYOCARDIAL INFARCTION - DETAILED FLOWCHART

CORONARY ARTERY OCCLUSION
            │
            ▼
     ATP depletion (seconds)
            │
     Loss of contractility (<2 min)
            │
     ATP 50% of normal (10 min)
            │
     ATP 10% of normal (40 min)
            │
     IRREVERSIBLE CELL INJURY (20-40 min)
            │
            ▼
     COAGULATIVE NECROSIS
     Begins SUBENDOCARDIAL (most vulnerable zone)
            │
            ▼
     "Wavefront of necrosis" moves outward
     → TRANSMURAL INFARCT (after ~6-12 hrs without reperfusion)

TIMELINE OF MI MORPHOLOGY (HIGH-YIELD TABLE)

Mnemonic for PMN peak = Day 1-3; Macrophages = Day 3-7; Granulation tissue = Week 1-2; Scar = >2 months

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COMPLICATIONS OF MI (flowchart by timing)

MYOCARDIAL INFARCTION
        │
 ┌──────┴──────────────────────────────────────────┐
 ▼ EARLY (hours-days)      ▼ LATE (weeks-months)
 - Arrhythmia (VF)         - Dressler syndrome
   [most common cause        (autoimmune pericarditis,
    of death <24 hrs]         2-10 wks post-MI)
 - Cardiogenic shock        - Ventricular aneurysm
   (if >40% LV destroyed)    (fibrous wall bulge → thrombus)
 - Acute pericarditis       - Mural thrombus → embolism
   (1-3 days)               - Progressive CHF
 - Wall rupture (3-7 days)  - Papillary muscle fibrosis
   → Cardiac tamponade        → chronic MR
 - Papillary muscle
   rupture → acute MR

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📌 TOPIC 3: HYPERTENSIVE HEART DISEASE (HHD)

CHRONIC HYPERTENSION
        │
        ▼
↑ Afterload on LV (Pressure overload)
        │
        ▼
LV CONCENTRIC HYPERTROPHY
(Wall thickness >2cm; Heart weight >500g)
        │
        ▼
DIASTOLIC DYSFUNCTION
(Stiff, non-compliant LV → impaired filling)
        │
  ┌─────┴──────┐
  ▼            ▼
Compensated   Decompensated
(asymptomatic) → LA enlargement → AF
               → IHD (demand ischemia)
               → CHF / SCD

• Gross: Concentric LV hypertrophy, wall >2 cm, heart weight >500 g
• Micro: Enlarged myocyte nuclei ("boxcar nuclei"), interstitial fibrosis
• Right-sided HHD (Cor Pulmonale): Due to pulmonary HTN → RV hypertrophy

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📌 TOPIC 4: VALVULAR HEART DISEASE

OVERVIEW

VALVE DISEASE
    │
 ┌──┴──┐
 ▼     ▼
STENOSIS    INSUFFICIENCY (Regurgitation)
(Failure     (Failure to close completely
to open)      → backflow)
    │              │
Pressure      Volume overload
overload      → dilation
→ hypertrophy

KEY VALVULAR DISEASES TABLE

Rheumatic Heart Disease Exam Points:

• Most commonly affects: Mitral > Aortic > Tricuspid > Pulmonary
• Aschoff bodies = pathognomonic granuloma of RHD
• Aschoff cells + Anitschkow cells (caterpillar cells)
• MacCallum plaques = irregular thickening of LA wall (endocardial plaque)

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INFECTIVE ENDOCARDITIS COMPARISON

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📌 TOPIC 5: CARDIOMYOPATHIES

THREE PATTERNS - COMPARISON DIAGRAM

┌────────────────────────────────────────────────────────────────┐
│                     CARDIOMYOPATHY                             │
├───────────────┬─────────────────┬──────────────────────────────┤
│   DILATED     │   HYPERTROPHIC  │     RESTRICTIVE              │
│   (DCM)       │   (HCM)         │     (RCM)                    │
├───────────────┼─────────────────┼──────────────────────────────┤
│ LVEF <40%     │ LVEF 50-80%     │ LVEF 35-55%                  │
│ Systolic      │ Diastolic       │ Diastolic                    │
│ dysfunction   │ dysfunction     │ dysfunction                  │
├───────────────┼─────────────────┼──────────────────────────────┤
│ Causes:       │ Causes:         │ Causes:                      │
│ - Genetic     │ - Genetic       │ - Amyloidosis                │
│ - Alcohol     │   (sarcomere    │ - Radiation fibrosis         │
│ - Peripartum  │    mutations,   │ - Idiopathic                 │
│ - Myocarditis │    MYH7, MYBPC3)│                              │
│ - Hemochromatosis│ - Friedreich │                              │
│ - Anthracyclines│  ataxia       │                              │
├───────────────┼─────────────────┼──────────────────────────────┤
│ MORPHOLOGY:   │ MORPHOLOGY:     │ MORPHOLOGY:                  │
│ - Dilated,    │ - Asymmetric    │ - Normal/slightly            │
│   flabby heart│   septal hyper- │   enlarged heart             │
│ - All 4       │   trophy (ASH)  │ - Stiff, non-                │
│   chambers    │ - Banana-shaped │   compliant wall             │
│   enlarged    │   LV cavity     │ - Biatrial dilation          │
│ - Mural       │ - Systolic      │                              │
│   thrombi     │   anterior      │                              │
│               │   motion (SAM)  │                              │
│               │   of mitral     │                              │
│               │   valve         │                              │
├───────────────┼─────────────────┼──────────────────────────────┤
│ MICROSCOPY:   │ MICROSCOPY:     │ MICROSCOPY:                  │
│ - Myocyte     │ - Myocyte       │ - Amyloid deposits           │
│   hypertrophy │   disarray      │   (Congo red +)              │
│ - Interstitial│   (pathognomonic│ - Diffuse interstitial       │
│   fibrosis    │   for HCM)      │   fibrosis                   │
└───────────────┴─────────────────┴──────────────────────────────┘

HCM High-Yield: Myocyte disarray = pathognomonic; LVOT obstruction; cause of SCD in young athletes; autosomal dominant (MYH7/MYBPC3 mutations)

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📌 TOPIC 6: CONGENITAL HEART DISEASE (CHD)

CLASSIFICATION FLOWCHART

CONGENITAL HEART DISEASE
          │
   ┌──────┴──────┐
   ▼             ▼
LEFT-TO-RIGHT  RIGHT-TO-LEFT    OBSTRUCTIVE
SHUNTS         SHUNTS           LESIONS
(Acyanotic)    (Cyanotic)
   │               │                 │
 ASD           Tetralogy of     Aortic coarctation
 VSD           Fallot (TOF)     Pulmonary stenosis
 PDA           TGA (Transposition)  Aortic stenosis
               Truncus arteriosus
               Tricuspid atresia

LEFT-TO-RIGHT SHUNTS (Acyanotic - "Late cyanosis")

L→R shunt (ASD/VSD/PDA)
     │
     ▼
↑ Pulmonary blood flow
     │
     ▼
Pulmonary vascular remodeling
     │
     ▼
↑ Pulmonary vascular resistance
     │
     ▼
Pulmonary Hypertension
     │
     ▼
RV Pressure > LV Pressure
     │
     ▼
REVERSAL OF SHUNT → R→L shunt
     │
     ▼
EISENMENGER SYNDROME
(Late cyanosis, polycythemia, paradoxical emboli)

TETRALOGY OF FALLOT (TOF) - The Classic "Blue Baby"

4 Components:
1. VSD (large)
2. Overriding Aorta (sits over VSD)
3. Pulmonary stenosis (RVOT obstruction)
4. RV hypertrophy (secondary to PS)

Pathophysiology:
Pulmonary stenosis → ↑RV pressure
         │
         ▼
R→L shunt through VSD
         │
         ▼
Deoxygenated blood → systemic circulation
         │
         ▼
Cyanosis + Clubbing + Polycythemia

"Tet spells" (hypercyanotic episodes) → Squatting relieves symptoms
(↑systemic resistance → ↓R→L shunt)

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📌 SUMMARY: HIGH-YIELD EXAM QUICK REFERENCE

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❤️ HEART PATHOLOGY - ROBBINS

Complete Morphology Guide with Diagrams

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1. ISCHEMIC HEART DISEASE (IHD) & MYOCARDIAL INFARCTION

Progression of Necrosis - Textbook Diagram

Key point: Necrosis begins SUBENDOCARDIAL (most vulnerable - last to receive blood, highest intramural pressure). With prolonged ischemia the wavefront moves centripetally outward → Transmural infarct by 6-12 hrs.

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Infarct Distribution by Artery - Textbook Diagram

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MI Morphology - Sequential Changes

GROSS MORPHOLOGY TIMELINE

TIME          GROSS APPEARANCE
─────────────────────────────────────────────────────────
0-4 hrs    → Nothing visible (normal gross)
4-12 hrs   → Subtle dark mottling / early pallor
12-24 hrs  → Pale, tan-yellow infarct center
1-3 days   → Yellow-tan pallor (well defined)
3-7 days   → Yellow-soft center + HYPEREMIC (red) rim
            (most vulnerable to RUPTURE - day 3-7!)
1-2 weeks  → Depressed, pale, gelatinous border
2-8 weeks  → Gray-white scar forming
>2 months  → Dense white-gray SCAR (complete)

MICROSCOPIC TIMELINE - Textbook Photomicrographs

Exam tip: Wavy fibers = earliest microscopic sign (day 1). PMNs peak day 2-3. Macrophages day 3-7. Granulation tissue week 1-2. Scar = month 2+.

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Morphology Flow: Transmural vs Subendocardial

COMPLETE EPICARDIAL OCCLUSION      PARTIAL / TRANSIENT OCCLUSION
(no reperfusion)                   or GLOBAL HYPOTENSION
        │                                   │
        ▼                                   ▼
TRANSMURAL INFARCT              SUBENDOCARDIAL INFARCT
- Full-thickness necrosis       - Only inner 1/3 of wall
- ST elevation (STEMI)          - Circumferential (if shock)
- Single coronary territory     - Not limited to one artery

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2. HEART FAILURE - MORPHOLOGY

Left-Sided CHF Morphology

LEFT HEART FAILURE
        │
 ┌──────┴────────────────────────┐
 ▼ HEART                         ▼ LUNGS
 - LV hypertrophy + dilation     - Heavy, wet, boggy lungs
 - LA dilation (→ AF risk)       - Pulmonary edema
 - Mural thrombus (in LA)        - Hemosiderin-laden macrophages
 - Interstitial fibrosis           = "HEART FAILURE CELLS"
 - Myocyte hypertrophy           - Pleural effusion (serous)
                                  - "Brown induration" (chronic)

Heart failure cells = macrophages stuffed with hemosiderin (from phagocytosed RBCs that leaked into alveoli). Pathognomonic of LEFT heart failure.

Right-Sided CHF Morphology

RIGHT HEART FAILURE
        │
 ┌──────┴──────────────────────────────────┐
 ▼ LIVER                    ▼ OTHER ORGANS
 - "NUTMEG LIVER"           - Splenomegaly (congestion)
   (centrilobular           - Peripheral edema
   congestion = dark)       - Ascites
   (periportal = pale)      - Pleural effusion
 - Cardiac cirrhosis        - Jugular venous distension
   (chronic)

Nutmeg liver = alternating dark (congested centrilobular zone) + pale (normal periportal zone) = classic of RIGHT CHF

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3. HYPERTENSIVE HEART DISEASE (HHD) - MORPHOLOGY

SYSTEMIC HTN
    │
    ▼
PRESSURE OVERLOAD on LV
    │
    ▼ GROSS:
    - LV wall thickness >2 cm (normal ~1 cm)
    - Heart weight >500 g (normal ~300-350 g)
    - CONCENTRIC hypertrophy (wall thick, cavity small)
    - Left atrial enlargement (from diastolic dysfunction)
    │
    ▼ MICROSCOPY:
    - ↑ Myocyte transverse diameter
    - "BOXCAR NUCLEI" (enlarged, rectangular)
    - Perivascular + interstitial fibrosis

CONCENTRIC (Pressure overload - HTN, AS)
  ┌─────────────────────┐
  │  ████████████████   │  ← Thick wall
  │  ██             ██  │  ← Small cavity
  │  ████████████████   │
  └─────────────────────┘

ECCENTRIC (Volume overload - MR, AR, DCM)
  ┌─────────────────────┐
  │  ██             ██  │  ← Thin wall
  │  ██               ██│  ← Large cavity
  │  ██             ██  │
  └─────────────────────┘

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4. VALVULAR HEART DISEASE - MORPHOLOGY

Rheumatic Heart Disease - Textbook Image

RHD Morphology Flowchart

GROUP A STREP PHARYNGITIS
        │
        ▼ (2-3 week delay)
MOLECULAR MIMICRY
Anti-strep antibodies cross-react with cardiac proteins
        │
        ▼
ACUTE RHEUMATIC FEVER (PANCARDITIS)
        │
  ┌─────┴──────────────────────────────┐
  ▼ PERICARDITIS    ▼ MYOCARDITIS      ▼ ENDOCARDITIS
  Fibrinous         ASCHOFF BODIES     Small (1-2mm) verrucae
  pericarditis      (granulomas with   along lines of valve
                    Anitschkow cells)  closure
                    "Caterpillar cells"
                    MacCallum plaques
                    (LA wall)
        │
        ▼ CHRONIC (years of scarring)
MITRAL STENOSIS ("Fish mouth" / "Buttonhole")
- Leaflet thickening + fusion
- Commissural fusion
- Short, thick, fused chordae tendineae
- Calcification

Aschoff Body = Granuloma
├── Central fibrinoid necrosis
├── T lymphocytes
├── Plasma cells
└── ANITSCHKOW CELLS (macrophages)
    = "Caterpillar cells"
    = Elongated wavy chromatin in nuclei
    = Pathognomonic of RHD

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Mitral Valve Prolapse (MVP) - Myxomatous Degeneration

• Gross: "Hooding/billowing" of posterior (sometimes both) leaflets into LA
• Microscopy: Expansion of spongiosa layer (proteoglycans - blue on Movat stain); disrupted fibrosa (loose, disorganized collagen)
• Sound: Mid-systolic click ± late systolic murmur

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Calcific Aortic Stenosis - Morphology

CALCIFIC (DEGENERATIVE) AORTIC STENOSIS
        │
GROSS:
- Heaped-up calcified masses on OUTFLOW surface of cusps
- Free edges of cusps NOT involved (unlike RHD)
- "Rock-hard" nodular calcium deposits
- Restricted cusp opening

MICROSCOPY:
- Preserved layered valve architecture
- Calcium deposition in fibrosa layer
- Osteoblast-like cells (bone matrix proteins)
- Does NOT resemble atherosclerosis histologically

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Infective Endocarditis - Morphology

INFECTIVE ENDOCARDITIS
        │
   ┌────┴────────┐
ACUTE IE         SUBACUTE IE
(S. aureus)      (S. viridans)
        │               │
LARGE, BULKY,      SMALL, FLAT
DESTRUCTIVE        VEGETATIONS
VEGETATIONS        (less destruction)
- Destroy normal   - On damaged valves
  valves           (bicuspid, MVP, RHD)
- Ring abscesses   - Indolent course
- Perforation
        │
        ▼ BOTH TYPES CAUSE:
Emboli (septic infarcts - brain, kidney, spleen)
Osler nodes (painful, fingertips)
Janeway lesions (painless, palms/soles)
Roth spots (retinal hemorrhages)
Splinter hemorrhages (under nails)

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5. CARDIOMYOPATHIES - MORPHOLOGY

Visual Comparison - Textbook Diagram

DCM vs HCM - Causes, Pathology, Clinical Features

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Dilated Cardiomyopathy (DCM) - Detailed Morphology

DILATED CARDIOMYOPATHY
        │
GROSS:
- Heart 2-3x normal weight ("flabby, heavy heart")
- ALL FOUR CHAMBERS dilated
- Flabby, hypocontracting walls
- Mural thrombi (common in atrial appendages / apex)
- No primary valve pathology

MICROSCOPY:
- Myocyte hypertrophy (variable)
- Attenuated, stretched myocytes
- Interstitial + endocardial fibrosis
- Small subendocardial scars
- "Ninja star nuclei" in titin mutation DCM
  (hyperchromatic, distorted nuclei)

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Hypertrophic Cardiomyopathy (HCM) - Detailed Morphology

HYPERTROPHIC CARDIOMYOPATHY
        │
GROSS:
- Massive hypertrophy WITHOUT dilation
- ASYMMETRIC SEPTAL HYPERTROPHY (ASH) = classic
  (septum:free wall ratio >1.3)
- "Banana-shaped" LV cavity
- LV outflow tract plaque (endocardial thickening
  from contact with anterior mitral leaflet)
- Normal or small LV cavity

MICROSCOPY (4 key features):
1. Massive myocyte hypertrophy (diameter >40μm; normal ~15μm)
2. MYOFIBER DISARRAY = pathognomonic!
   (haphazard arrangement of bundles + sarcomeres)
3. Fibrotic narrowing of small intramural arteries
4. Interstitial and replacement fibrosis

MYOFIBER DISARRAY = Pathognomonic of HCM - myocytes arranged in chaotic, pinwheel-like patterns instead of parallel rows.

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Restrictive Cardiomyopathy (RCM) - Morphology

RESTRICTIVE CARDIOMYOPATHY
        │
GROSS:
- Normal or slightly enlarged ventricles
- NO ventricular dilation
- BIATRIAL DILATION (from impaired filling → backup)
- Stiff, non-compliant walls

MICROSCOPY:
- Patchy or diffuse interstitial fibrosis
- Amyloidosis (#1 cause):
  - Deposits in myocardial interstitium
  - CONGO RED stain → apple-green birefringence
  - "Sparkling" appearance on echo

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6. CONGENITAL HEART DISEASE - MORPHOLOGY SUMMARY

LEFT-TO-RIGHT SHUNTS          RIGHT-TO-LEFT SHUNTS
(Acyanotic early)             (Cyanotic from birth)

ASD:                          TOF (4 components):
- Secundum type most common   1. Large VSD
- LA + RA dilation            2. Overriding aorta
- RV hypertrophy (late)       3. Pulmonary stenosis
                              4. RV hypertrophy

VSD:                          Gross finding: "Boot-shaped heart"
- Membranous most common      (RV hypertrophy = coeur en sabot)
- RV pressure overload
- Eisenmenger if large        TGA:
                              - Aorta from RV (anterior)
PDA:                          - PA from LV (posterior)
- Continuous "machinery"      - Two parallel circuits
  murmur                      - Not compatible with life
- LA + LV dilation              without mixing (VSD/ASD/PDA)

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MASTER MORPHOLOGY QUICK-REFERENCE TABLE

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