Myocarditis & Cardiomyopathy

Question 1

The provided image is an examle of what?

Label the indicated features

Answer 1

healthy heart

P: pericardium

M: myocardium

E: epicardium

PM: papillary muscle

Question 2

The provided image is an example of what?

Answer 2

Healthy pericardium & myocardium

F: fibrous pericardium

M: myocardium

CA: coronary artery

Question 3

The provided image shows what histology?

Answer 3

normal myocardium

Question 4

The provided image shows what histology?

Answer 4

normal endocardium (lighter on top of image)

normal myocardium (pinker bottom of image)

Question 5

What is the definition of cardiomyopathy?

What are the three main types?

Answer 5

dysfunction of the myocardium, not secondary to ischemia, valvular disease, or hypertension

1. Dilated CM: Large, flabby heart with ventricular dilation, +/- ventricular thickening; systolic dysfunction
2. Hypertrophic CM: thickened, stiff left ventricle and septum; no ventricular dilation; diastolic dysfunction
3. Restrictive CM: Rare. Rigid, but not necessarily thickened ventricles, diastolic dysfunction

Question 6

The heart on the left shows what pathology as compared to the normal heart on the right?

What are the primary causes of this pathology?

Answer 6

Dilated Cardiomyopathy, 4 chamber dilation

• Primary causes
  
  • idiopathic – up to 50%
  • familial – 30-50% (many mutations
    
    • mostly proteins of cytoskeleton, could be sarcolemma or nuclear envelope proteins

Question 7

What is the most common type of cardiomyopathy?

Answer 7

dilated cardiomyopathy

Question 8

Identify the indicated proteins & the type of cardiomyopathy that would result from a mutation in said gene.

** unclear how important it is to memorize this

Answer 8

• Red: dilated cardiomyopathy
  
  • delta-sarcoglycan
  • dystrophin
  • desmin
  • mitochondrial proteins
  • titin
  • lamin A/C
• Blue: hypertrophic cardiomyopathy
  
  • myosin binding protein C
  • myosin light chains
• Green: either (but different mutation)
  
  • troponin I/T
  • alpha-tropomyosin
  • actin
  • beta-myosin heavy chains

Question 9

What are the secondary causes of dilated cardiomyopathy? They account for what overall percent of dilated cardiomyopathy?

Answer 9

• Secondary Causes – 50% all cases
  
  • inflammatory
    
    • post-infectious (especially viral)
    • non-infectious
      
      • autoimmune diseases (ie. lupus)
      • peripartum cardiomyopathy (late pregnancy/postpartum)
      • sarcoidosis
  • neuromuscular
    
    • Muscular or myotonic dystrophy
  • toxic
    
    • chronic ETOH toxicity
    • heay metals, iron overload
    • chemotherapeutic agents (doxorubicin, tratuzumab)
  • metabolic disorders
    
    • hypothyroidism (esp. older individuals)
    • chronic hypocalcemia or hypophosphatemia

Question 10

What are the clinical features of dilated cardiomyopathy?

Answer 10

• Clinical features
  
  • heart failure
    
    • pulmonary congestion (LV dysfunction)
      
      • dyspnea, exercise intolerance, orthopnea
    • chronic systemic venous congestion (RH/combon LV & RH failure)
      
      • jugular venous distension, ascites, pedal edema
  • arrhythemia
  • thromboembolic complications
• clinical course is unpredictable
  
  • depends on person & type of dilated cardiomyopathy
  • some cases may recover, some may not

Question 11

The provided image is an example of what pathology?

What histological features do you notice?

Answer 11

• Dilated Cardiomyopathy
• Pretty nonspecific
  
  • myocyte hypertrophy (red)
  • interstitial fibrosis (blue = collagen)
    
    • can end up with conduction disturbances
• may also see some thrombus due to stasis
  
  • white arrow in gross image

Question 12

Describe how myocyte injury can lead to pulmonary congestion, systemic congestion & mitral regurgitation.

What clinical presentation would you expect with these conditions?

Answer 12

Question 13

How does the kidney respond to a decrease in cardiac outlfow? This ultimately has what effect on the heart?

Answer 13

• When cardiac outflow is declining, blood flow to kidney will also decrease
• This prompts kidney to secrete renin –> activating the renin, angiotensin, aldosterone system forcing the body to retain more salt & with that fluid to try to increase the intervascular volume
• this worsens the condition, because the heart is already not working properly & increasing intervascular volume increases the workload on the heart

Question 14

The provided image is an example of what pathology?

What are the caracteristics of this condition?

Answer 14

Hypertrophic Cardiomyopathy

heart is heavy, muscular, hypercontractile & stiff with poor diastolic relaxation. Asymmetrical septal hypertrophy

ventricular outflow obstruction in 1/3 of cases (anterior leaflet may be flapping up against the endocardium causing thickening and perhaps plaque formation)

Question 15

Mutations in what three genes account for 70-80% of all hypertrophic cardiomyopathy?

Answer 15

1. beta-myosin heavy chain
2. myosin binding protein C
3. troponin T

Question 16

What is the most common cause of hyertrophic cardiomyopathy?

What demographics are most effected?

Answer 16

100% inherited

Incidence 1/500

all age groups

no populatin predilection

Question 17

What is the most common cause of sudden cardiac death in young athletes?

Answer 17

hypertophic cardiomyopathy

Question 18

What are the clinical features of hypertrophic cardiomyopathy?

Answer 18

• often asymptomatic
• syncope
• palpitations
• exertional dyspnea
• chest pain
• atrial fibrillation
• sudden cardiac death

Question 19

Describe how myocyte hypertrophy & dynamic left ventricle outflow obstruction can lead to angina, dyspnea, syncope and sudden death.

Answer 19

Question 20

The provided image is an example of what pathology?

What are the key histological fearures?

Answer 20

hypertrophic cardiomyopathy

myocyte disarray

interstitial fibrossis (pink in between the myocytes in image C)

Trichrome stain (D): stains collagen blue, you can see the large amounts of collagen

Question 21

What are the common clinical features of dilated cardiomyopathy and hypertrophic cardiomyopathy?

Answer 21

heart failure

sudden death

atrial fibrilation

stroke

Question 22

The provided image is an example of what type of pathology?

Prominent features?

Answer 22

Restrictive Cardiomyopathy

• Left: prominent biatrial dilation
• Right: prominent interstitial fibrosis

Question 23

The provided images are an example of what type of pathology?

Answer 23

Amyloidosis – can cause restrictive cardiomyopathy

• H&E- pale pink, smudgy material
• Congo Red, polarized Amyloid (upper half) is green

Question 24

What is the most common cause of restrictive cariomyopathy in non-tropical countries? Most affected demographic?

What is the most common cause of restrictive cardiomyopathy in tropical countries? Most affected demographics?

Answer 24

• non-tropical
  
  • Amyloidosis
  • middle aged & older adults
• tropical - nutritional deficiencies and worm infections (hypereosinophilia)
  
  • endomyocardial fibrosis
  • children & young adults

Question 25

How can a **rigid myocardium** lead to _jugular vein distension_, _hepatomegaly & ascites_, _peripheral edema_, _weakness_, and _fatigue_?

Answer 25

Question 26

The provided image is an example of what type of pathology? How is it acquired? Prominent features? Most commonly affected demographic

Answer 26

**Arrhythmogenic Right Ventricular Cardiomyopathy** inherited Right ventricle is makedly dilated & the wall is largely replaced wiht fat & fibrosis adolescents & young adults

Question 27

Arrhythmogenic Right Centricular Cardiomyopathy is most often caused by mutations to what genes?

Answer 27

* **desmosomal junctional proteins** found in intercalated discs of cardiac myocytes * other proteins that interact with **desmosomes**

Question 28

What are the anatomial features of stress-induced (takotsubo) cardiomyopathy? Cause?

Answer 28

* enlarged ventricle pumps blood less efficiently * also has odd shape * Stress: emotional or physical * stunning of the myocardium by a mark increase in catecholamines * other caues of excess catecholamines do not produce the "ballooning" in the left ventricular apex

Question 29

What is the definition of myocarditis? What are the common causes?

Answer 29

* **myocarditis:** inflammation of the myocardium, associated with myocyte necrosis & degeneration * infections (cause of necrosis) * immune-mediated * toxin-mediated * drug toxicity * miscellaneous

Question 30

What is the most common type of infectious myocarditis in the US? What are the phases & in what phase could you see dilated cardiomyopathy?

Answer 30

viral myocarditis * phases * acute phase (virsu replication) * subacute phase (immune response) * chronic phase (dilated cardiomyopathy)

Question 31

The provided images are an example of what pathology?

Answer 31

viral myocarditis Inflammatory infiltrate: mononuclear cells, lymphocytes, plasma cells & macrophages -- depending on cause may have eosinophils

Question 32

The the provided image is an example of what type of pathology? Important histological features?

Answer 32

Chagas Disease Myocarditis myocytes have numerous amastigotes (black curved arrows) forming pseudocysts

Question 33

The the provided image is an example of what type of pathology? Cause?

Answer 33

Trichinella spiralis myocarditis Helminth is visible form side & cross section * ingestion of uncooked/raw pork * eating wild game (most common)

Question 34

What are the most important causes of non-infectious myocarditis?

Answer 34

* post-viral (from immune response) * post-streptoccal (rheumatic fever) * autoimmune/collagen-vascular diseases * drug hypersensitivity * transplant rejection

Question 35

The the provided image is an example of what type of pathology? Important histological features?

Answer 35

**Streptococcal myocarditis** * **Aschoff body** of acute rheumatic fever (upper photo) * **Anitschkow macrophages** (caterpillar cells) shown by the red arrows are pathognomonic for rheumatic fever

Question 36

The the provided image is an example of what type of pathology? Important histological features?

Answer 36

**Hypersensitivity Myocarditis** increaed eosinophils with fewer lymphocytes predominantly interstitial inflammation with minimal myocyte damage (black arrows)