Definition
Inflammation of the endocardium (inner layer of the heart), which primarily affects the heart valves but may also involve the interventricular septum, chordae tendineae, and the mural endocardium. Most often, valves on the left side of the heart (mitral, aortic) are affected due to higher pressure and turbulence.
Classification
- Infective – caused by microbial infection, mostly bacteria.
- Non-infective – sterile vegetations that can occur in hypercoagulable states (e.g., malignancy, systemic lupus erythematosus), and may later become infected (secondary infection).
Etiology
- Mostly bacterial (fungi less common) → i.e., infective endocarditis.
- Risk factors include:
- Valvular heart disease (e.g., rheumatic valve disease)
- Congenital heart defects (CHD)
- Artificial valves (prosthetic valves)
- Hemodialysis (frequent vascular access = entry of pathogens)
- IV drug use (introduces skin flora directly into the bloodstream)
- Cardiac devices (pacemakers, ICDs – foreign body increases infection risk)
- Causative organisms:
- Streptococci (especially viridans group – linked to dental procedures, subacute course)
- Staphylococci (especially aureus – aggressive, causes acute endocarditis)
- Non-infective endocarditis: Usually occurs during a hypercoagulable state like severe illness, pregnancy, or cancer. Inflammation causes sterile vegetations that may embolize and cause infarctions.