Pathology Of Endocarditis, Myocarditis, Pericarditis

Question 1

3 major layers/walls of the myocardium

Answer 1

Internal endocardium

Middle myocardium

External epicardium

Question 2

What layers are in endocardium?

Answer 2

Thin inner layer of endothelium and supporting CT

Middle myoelastic layer of smooth muscle fibers

Deep layer of CT called subendocardial layers that merges with the myocardium

Question 3

What is the thickest layer of the heart

Answer 3

Myocardium

Question 4

Epicardium layer details

Answer 4

Simple squamous mesothelioma layer supported by CT

Contains blood vessels and nerves

Corresponds to the visceral layer of the pericardium and contains lubricant fluid which prevents friction

Question 5

Infective endocarditis

Answer 5

Microbial infection of the heart valves or the mural endocardium that leads to the formation of vegetations

Vegetations =. Thrombotic debris and organisms combined

Question 6

Classifications off infective endocarditis

Answer 6

Acute: refers to destreuctive infections w/ Highly virulent organisms attacking previously normal valves
- significant morbidity and mortality exists even w/ antibiotic therapy

Subacute: refers to infections by organisms of low virulence affecting previously abnormal heart tissue
- typically appears insidiously and recovers fine after antibiotic therapy

Based of the tempo and severity of the clinical course

Question 7

Cardiac abnormalities that predispose to infective endocarditis

Answer 7

Rheumatic heart disease

Mitral valve prolapse

Bicuspid aortic valves

Calcified valvular stenosis

Prosthetic heart valves (accounts for 10-20% of all cases)

Sterile platelet fibrin deposits at sites of pace markers

Neutropenia, immunodeficiencies, cancer, diabetes and drug/alcohol abuse

Question 8

What organism is most commonly found during infective endocarditis

Answer 8

50-60% are caused by streptococcus viridans

10-20% are caused by staph aureus
- almost all cases are seen in IV drug users with endocarditis

Question 9

HÁČEK group

Answer 9

Group of bacterial agents that can also cause infective endocarditis

Haemophilus

Actinobacillus

Cardiobacterium

Elkenella

Kingella

Question 10

Culture-negative endocarditis

Answer 10

Occurs in 10% of cases

No organism is isolated from the blood culture since it is difficult to isolate
- often causes by strong previous antibiotic therapies

Question 11

What is the primary pathogenesis factor predisposing to Infectious endocarditis?

Answer 11

Seeding of the blood with microbes (bacteremia)

Causes include

• surgical procedures
• wounds
• IV drug users
• etc.

Question 12

What are the most common sites of infective endocarditis?

Answer 12

Aortic and mitral valves are the most common site

Note: tricuspid is the most common in IV drug abusers

The vegetation are friable, bulky a vegetations containing fibrin, inflammatory cells and microorganisms

Question 13

Why are septic infarcts and mycotic aneurysms common in untreated infective endocarditis

Answer 13

Vegetations on the valves can break off and lodge somewhere, causing an abscess and septic issues.

Question 14

Does subacute or acute cause less valvular destruction?

Answer 14

Subacute

Question 15

What is the most common clinical symptoms for infective endocarditis?

Answer 15

Fever and heart murmurs (typically at aortic or mitral valve places)

Can also include the following

• weight loss
• flulike symptoms
• splenomegaly
• chills
• weakness
• malaise

Question 16

What are systemic symptoms that can be causes my micro-emboli formed through infective endocarditis?

Answer 16

Petechiae in fingers and nail beds
- splinter appearance

Hemorrhages (especially retinal)
- Roth spots

Painless palm lesions
- Janeway lesions

Painful finer tip nodules
- osler nodes

Question 17

How to confirm infective endocarditis?

Answer 17

Positive blood cultures and TEE images

- shows large leaflets in the left valves

Question 18

What are possible sequelae associated with untreated infective endocarditis?

Answer 18

Glomerulonephritis

Hematuria

Albuminuria

Renal failure

Septicemia

Systemic embolization

Terminal arrhythmias

Question 19

What are the mortality rates of infective endocarditis when treated vs not treated

Answer 19

Untreated low and high virulence = 98%

Low virtual virulence treated = 2%

High virulence treated = 10-30%

Question 20

Non bacterial thrombotic endocarditis (NBTE)

Answer 20

Deposition of sterile thrombi on cardiac valves
- often seen in Hyper-coagulability states

Are nondestructive and also called “marantic endocarditis” since they are directly associated with patients who are generally disabled or wasting

Question 21

What is the most common precursor for NBTE?

Answer 21

Hypercoagulability state

• these include:
  1) history of DIC
  2) hyper estrogen is states
  3) having cancer

NOTE: these do not require valvular damage to be diagnosis disease, unlike infective endocarditis

Question 22

Why is NBTE dangerous?

Answer 22

The increased and likely chance of turning into an embolus if not treated, as well as being a safe haven for potential bacterial cultures (leading to IE)
- the valve damage is usually benign

Question 23

Most common cause of myocarditis

Answer 23

Coxsackieviruses A and B and enteroviruses
- also Chagas’ disease

To determine direct agent requires serology

Question 24

Chagas’ disease brief refresher

Answer 24

Caused by the protozoan trypanosomia Cruzi

• uncommon in the northern hemisphere but very common in South American
• 10% of patients die during an acute attack
• can also manifest and remain as chronic inflammation, leading to CHF or lethal arrhythmias after 10-20 yrs left untreated

Question 25

Lyme disease in myocarditis

Answer 25

Is possible, but rare (5%)
- caused by the bacterial spirochete borrelia burgdorferi

Requires temporary pacemaker while disease runs its course if myocarditis is present

Question 26

Microscopic morphology of myocarditis

Answer 26

Edema and interstitial inflammatory infiltrates w/ myocyte injury

Chagas myocarditis specifically shows trypanosomes within the myofibrils s occupancies with inflammatory cells

Note: if patient survives, the lesions will usually progress to fibrosis

Question 27

Myocarditis clinical features and symptoms

Answer 27

Very broad spectrum of clinical features

• can be asymptomatic and patients can recover without Tx
• can also result in CHF, lethal arrhythmias and SCD

Symptoms include the following:

1) fatigue
2) dyspnea
3) palpitations
4) pain
5) fever

Question 28

Pericarditis facts

Answer 28

Primary (uncommon):
- caused by viral infections (and therefore often occurs concurrent with myocarditis)

Secondary (More common)

• untreated uremia
• post acute myocardial infractions and cardiac surgery as well (Dressler syndrome)
• pneumonia
• SLE
• rheumatic heart disease

Question 29

Most common systemic disorder of pericarditis

Answer 29

Uremia

- uremia leads to pericarditis often if untreated

Question 30

Cardiac tamponade w/ pericarditis

Answer 30

Can cause cardiac tamponade in some cases

Question 31

Acute viral vs acute bacterial pericarditis exudate

Answer 31

Acute viral = exudate is irregular, shaggy and fibrinous in appearance

Acute bacterial = Purulent with regular shape and fibrinous

Question 32

Clinical features of pericarditis

Answer 32

Atypical chest pain and prominent friction rub feeling

Can also show cardiac tamponade, low CO and cardiogenic shock

ECG:

• shows diffuse ST elevation w/ PR depression
• if cardiac effusion is present, may also show electrical alternans