Infective endocarditis and prosthetic valves Flashcards
Define infective endocarditis
Infection of:
- Heart valves: normal or prosthetic
- Endothelial surface of the heart
- Congenital defects eg. VSD, PDA, valve defects
List the valves affected in infective endocarditis
(Commonest to rarest)
- Mitral valve
- Aortic valve
- Combined mitral and aortic
- Tricuspid valve: IVDU
- Pulmonary valve
Describe the pathophysiology of infective endocarditis
- Non-bacterial thrombotic endocarditis
- Endothelial damage or valve damage
- Promotes platelet and fibrin deposition
- Organisms adhere and grow, forming infected vegetation
- Biofilm protect the bacterial vegetation from host defence mechanisms
When does infective endocarditis’ incidence peak?
- Developing countries: Children and young adults
- Due to rheumatic fever
- Developed countries: 55-60yrs
Name four risk factors for infective endocarditis
- >60yr Male
- IVDU: includes tricuspid lesion
- HIV
- Poor dental hygiene
- Prosthetic heart valve
- Congenital heart defects
- Rheumatic valve disease: developing countries
- Mitral valve prolapse; bicuspid aortic valve
- Chronic haemodialysis
Name two pathogens associated with infective endocarditis
- Early (within 60d of valve surgery): poorer prognosis
- Staph aureus: acute presentation; IVDU
-
Staph epidermidis: nosocomial infection
- Peri-op + 2/12 post-op valve replacement
- Late (after 60d post-valve surgery)
- Strep viridans (5-60% of subacute cases)
- Staph aureus
- HACEK organisms (rare): more insidious
Fungal endocarditis may occur
List five presenting features of infective endocarditis
- Systemic: Fever, chills, anorexia, weight loss
- Murmur (85%), heart failure, conduction abnormalities
- Vascular phenomena:
- Stroke, MI, or embolisation to lung/spleen/kidney
- Splinter haemorrhage
- Janeway lesions: flat painless lesions on palms
- Immunologic phenomena:
- Osler’s nodes: swollen painful lesions on fingers
- Roth spots on fundoscopy
- Glomerulonephritis; rheumatoid factor
Differentiate between Janeway lesions and Osler’s nodes
- Janeway lesions: flat painless lesions on palms
- Osler’s nodes: swollen painful lesions on fingers
Describe the presentation of subacute infective endocarditis
- Fatigue, anorexia, weight loss
- Low-grade fever
- Flu-like illness
- Polymyalgia-like symptoms
- Back or pleuritic pain
- Abdominal symptoms
Name three causes of right-sided infective endocarditis
- IVDU
- HIV
- Cardiovascular devices
- eg. pacemaker wires; prosthetic right heart valves
Outline the Duke diagnostic criteria for infective endocarditis
Definite IE = 1 pathological; 2 major; 1 major + 3 minor; or 5 minor
- Pathological:
- Microorganisms in vegetation
- Pathologic lesions
- Major:
- Positive blood cultures
- Endocardial involvement
- Minor:
- Predisposing heart condition or IVDU
- Fever >38
- Vascular phenomena
- Immunological phenomena
- Microbiological evidence: does not meet ‘major’
Request four investigations for suspected infective endocarditis?
- FBC, U+Es, LFTs, CRP
- Blood cultures x3
- ECG: MI, heart failure, conduction abnormalities
- Echocardiogram: vegetations, abscess, valve damage
- Urinalysis: haematuria due to renal embolism
What is the mortality rate in untreated infective endocarditis?
Almost 100% mortality if untreated
Outline the treatment of infective endocarditis
Always consult a microbiologist and cardiologist
- Requires at least 4 weeks of IV antibiotics
- Dependent on organism
- Should respond within 48h
- Empirical ABX:
- Benzylpenicillin + Gentamicin
- Ceftriaxone/meropenam + Vancomycin
- Surgerical valve replacement
State three complications of infective endocarditis
- MI, pericarditis, arrhythmias
- Heart valve insufficiency
- Congestive heart failure
- Sinus of Valsalva aneurysm
- Aortic root abscess
- Arterial emboli or infarction
- Arthritis, myositis
- Glomerulonephritis, AKI
- Stroke; Mesenteric or splenic infarct
What types of prosthetic valves are available?
