Cardiac Valvular Diseases: Pathology Part 2

Question 1

What is infective endocarditis?

Answer 1

Infection of heart valve or endocardium

• colonization of heart valves or mural endocardium by a microbe
• leads to formation of vegetations composed of thrombotic debris and organisms
• associated with destruction of underlying cardiac tissues

Question 2

What can become infected in IE?

Answer 2

Can occur on normal or abnormal valves

- Aorta, aneurysmal sacs, blood vessels and prosthetic valves can also become infected

Question 3

What is the most common cause of infective endocarditis?

Answer 3

Usually bacterial (bacterial endocarditis)

Question 4

What is important when dealing with infective endocarditis?

Answer 4

Prompt diagnosis, identification of the offending agent and treatment is important

Question 5

What are the common causative organisms in infective endocarditis?

Answer 5

Streptococcus Viridans (50-60%) 
Staphylococcus Aureus (10-20%) 
Enterococci 
HACEK 
Coagulase negative Staph epidermidis

Question 6

What are the two types (pathological classification) of infective endocarditis traditionally?

Answer 6

1. Acute

2. Subacute

Question 7

What is Acute IE?

Answer 7

Normal valve + highly virulent organism (e.g. S. Aureus), rapidly produces necrotising, ulcerative and destructive lesions
= Difficult to treat and cure
- Needs surgery, death

Question 8

What is subacute IE?

Answer 8

Abnormal / deformed valve + less virulent organism (e.g. S. Viridans), less destructive, slow protracted course, treated with antibiotics

Question 9

What are the factors that predispose to the development of IE?

Answer 9

Anything that leads to bacteraemia.

Other predisposing factors:

• Valve abnormalities
• Bacteremia
• RHD with valvular scarring
• Mitral valve prolapse
• Calcific valvular stenosis
• Congenital abnormal valves
• Prosthetic valves

Question 10

What are the morphological hallmarks of infective endocarditis?

Answer 10

Friable, bulky, potentially destructive vegetations containing fibrin, inflammatory cells, bacteria on the heart valves

Question 11

Which valves are usually affected by infective endocarditis?

Answer 11

Usually aortic and mitral valves

Question 12

What may the morphology of the vegetations in IE involve?

Answer 12

• Vegetations may be single, multiple, may involve more than 1 valve
• May erode into the underlying myocardium and cause an abscess
• Vegetations prone to embolise = abscesses and septic infarcts

Question 13

Which vegetations are less destructive in IE?

Answer 13

Subacute vegetations are less destructive

Question 14

How do all IE vegetations heal (acute and subacute)?

Answer 14

Both heal with fibrosis, calcification, chronic inflammation

Question 15

What are the three causes of non-infective endocarditis?

Answer 15

1. Acute rheumatic fever
2. Non-bacterial thrombotic endocarditis
3. Endocarditis of SLE

Question 16

What is NBTE?

Answer 16

Deposition of small, sterile thrombi on the leaflets of cardiac valves (in non-infective endocarditis)

Question 17

What vegetations are seen in non-infective endocarditis?

Answer 17

Vegetations = non-invasive, small bland thrombi
Not destructive but may be a source of systemic emboli
- assess with underlying systemic hypercoaguable state e.g. cancer

Question 18

What is another name for the Endocarditis of SLE?

Answer 18

Libman-Sacks Disease

Question 19

What is vegetations are seen in Libman-Sacks Disease?

Answer 19

Mitral and tricuspid valves with small sterile vegetations

- may be seen on the undersurfaces of valves.

Question 20

Which side of the heart is affected in infective endocarditis in IV drug users?

Answer 20

Right side (normally = left) 
- because the blood (containing pathogens from dirty needles returns to the right side of the heart and causes infection)