15 Infective endocarditis Flashcards
What are the causes of infective endocarditis and non-infective endocarditis?
Bacteria (e.g. staphylococcus aureus) and fungi (e.g. candida). In IE, the bacteria or fungi are introduced via bacteraemia, device implantation or surgery.
Libman Sacks endocarditis in SLE. In non-IE, hypercoagulability, trauma, immune cells, vasculitis and adenocarcinomas can cause vegetations.
Describe the pathophysiology in infective endocarditis and non-infective endocarditis.
High velocity flow or turbulent flow causes endothelial injury. This causes platelets and fibrin to attach to the endocardium and form a sterile thrombus (NBTE lesion). In non-IE, microorganisms do not attach to the NBTE, but, in IE, microorganisms attach to the NBTE lesion and form a vegetation. The infection can spread within the heart and to other organs causing complications.
What are vegetations?
Vegetations are inflammatory masses of fibrin, platelets, RBCs, WBCs and micro-organisms.
On TTE, vegetations are echogenic, irregular and mobile (oscillate). Normally, vegetations are attached to the upstream side of the valve at the coaptation line. Vegetations move with the leaflet but move chaotically or prolapse.
What is the Duke Criteria for IE?
The major criteria include the presence of microorganisms in a vegetation or the presence of pathological lesions (diagnosis requires one). The major clinical criteria include positive blood cultures and evidence of endocardial involvement (diagnosis requires two). The minor criteria include an existing cardiac condition or IV drug use, fever, vascular phenomena, immunological phenomena and evidence of microbiological involvement (diagnosis requires all five).
What are the symptoms and signs of IE?
Fever, fatigue, anorexia, weight loss and/or flu like symptoms.
Fever, murmur, splinter haemorrhage, Janeway lesions, Osler’s nodes, Roth spots and/or peripheral emboli.
What are vegetations misdiagnosed for?
Thrombi (regular), tumours (bigger), normal variants (e.g. Eustachian valve) and abnormal variants (e.g. myxomas).
What are the typical and atypical locations of vegetations?
Valves.
Endocardium, chordae tendineae and intracardiac devices.
What are the complications of endocarditis?
Abscesses, fistulas, valvular destruction and transvalvular regurgitation, prosthetic valve dehiscence and paravalvular regurgitation and chronic vegetations.
An abscess is an area of pus within the heart tissue which develop due to the spread of the infection from the vegetation on the valve to the tissue. Abscesses can cause valvular perforation and/or destruction, fistulas and become a source of infection.
A fistula is an abnormal communication which can develop due to an infection or the rupture of an abscess (e.g. aortic root abscess). Fistulas can cause abnormal blood flow which affects chamber size and function.
Chronic vegetations are the fibrotic or calcified parts of the vegetations following the resolution of the infection. Chronic vegetations can cause stenosis or regurgitation.
What are the congenital heart diseases associated with endocarditis?
PDAs, TOF, VSDs, aortic coarctation, BAV, SLE and HCM.
Congenital heart diseases cause endocarditis via turbulent flow causing endocardial injury.
When are TTEs and TOEs indicated in endocarditis?
In patients with positive blood cultures, a TTE is indicated within 24 hours.
For patients with clinical characteristics of endocarditis but a negative or inconclusive TTE, a TOE is indicated. Repeat in 7-10 days.
For patients with prosthetic valve endocarditis, TOE is indicated.
How is IE treated?
Good oral hygiene, antibiotics and/or surgery.
