Cardiac Valvular Diseases: Pathology Part 2 Flashcards
What is infective endocarditis?
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
What can become infected in IE?
Can occur on normal or abnormal valves
- Aorta, aneurysmal sacs, blood vessels and prosthetic valves can also become infected
What is the most common cause of infective endocarditis?
Usually bacterial (bacterial endocarditis)
What is important when dealing with infective endocarditis?
Prompt diagnosis, identification of the offending agent and treatment is important
What are the common causative organisms in infective endocarditis?
Streptococcus Viridans (50-60%) Staphylococcus Aureus (10-20%) Enterococci HACEK Coagulase negative Staph epidermidis
What are the two types (pathological classification) of infective endocarditis traditionally?
- Acute
2. Subacute
What is Acute IE?
Normal valve + highly virulent organism (e.g. S. Aureus), rapidly produces necrotising, ulcerative and destructive lesions
= Difficult to treat and cure
- Needs surgery, death
What is subacute IE?
Abnormal / deformed valve + less virulent organism (e.g. S. Viridans), less destructive, slow protracted course, treated with antibiotics
What are the factors that predispose to the development of IE?
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
What are the morphological hallmarks of infective endocarditis?
Friable, bulky, potentially destructive vegetations containing fibrin, inflammatory cells, bacteria on the heart valves
Which valves are usually affected by infective endocarditis?
Usually aortic and mitral valves
What may the morphology of the vegetations in IE involve?
- 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
Which vegetations are less destructive in IE?
Subacute vegetations are less destructive
How do all IE vegetations heal (acute and subacute)?
Both heal with fibrosis, calcification, chronic inflammation
What are the three causes of non-infective endocarditis?
- Acute rheumatic fever
- Non-bacterial thrombotic endocarditis
- Endocarditis of SLE
What is NBTE?
Deposition of small, sterile thrombi on the leaflets of cardiac valves (in non-infective endocarditis)
What vegetations are seen in non-infective endocarditis?
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
What is another name for the Endocarditis of SLE?
Libman-Sacks Disease
What is vegetations are seen in Libman-Sacks Disease?
Mitral and tricuspid valves with small sterile vegetations
- may be seen on the undersurfaces of valves.
Which side of the heart is affected in infective endocarditis in IV drug users?
Right side (normally = left) - because the blood (containing pathogens from dirty needles returns to the right side of the heart and causes infection)
