Learning objectives
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Serious potentially fatal infection of cardiac valves and endocardium usually by bacteria. Infective destructive vegetations form and erode and destroy the heart valves. Vegetations contain fibrin, platelets, microorganisms. These can embolise the cerebral circulation. A useful rule of thumb is that any patient with a prosthetic valve or valvular heart disease with a stroke (ischaemic or haemorrhagic) must be considered to have endocarditis until proven otherwise. The fact that haemorrhagic transformation from an embolised mycotic vegetation is common and bleeding is seen on CT can mislead the unwary. Co-existing anticoagulation can also distract and be blamed. Check the CRP, send cultures and get and arrange an urgent echocardiogram. Marantic endocarditis is a non-bacterial endocarditis with aggregates of platelets to large vegetations on previously undamaged heart valves is dealt with in the cancer and stroke section.
Approximately 60-80% of those with IE have a Predisposing heart lesions. Mitral valve prolapse only carries appreciable risk where there is associated MR. Other risk groups are those IV drug users who get a tricuspid valve endocarditis with Staph aureus. Those with Bicuspid aortic valve are also at risk of aortic valve endocarditis.
The complications of Infective Endocarditis include Valve failure with heart failure, throwing off further septic emboli e.g. stroke, Glomerulonephritis and progressive renal failure, Aortic root abscess formation, further valve destruction with regurgitation and severe cardiac failure. Valvular abscess and Pericarditis
Medical: It is vitally important to try and obtain cultures of the organism to help guide therapy and so multiple aerobic and anaerobic blood cultures from multiple sites should be taken over 12-24 hrs prior to commencing antibiotics. If antibiotics have already been given this can make organism identification difficult. Ensure sufficient microbiological samples taken before starting blind therapy. Once the organism is known specific treatment is started usually a prolonged course of antibiotics is needed and determined by local advice and sensitivities. Usually requires 4-6 weeks of IV and then oral therapy. Streptococci - Penicillin G and Gentamicin. Methicillin Sensitive Staph Aureus - take expert guidance. Generally, anticoagulation is avoided if possible as there is a high risk of bleeding into infarcted areas.
Cardiac Surgical: urgent assessment needed for cardiac failure due to valve damage, extensive MR/AR, large vegetations, septic emboli, abscess formation, fungal infection, antibiotic resistance, failure to respond to medical management. Surgery is evidently high risk with significant risk of complications. Cardiothoracic centres may be reluctant to take those with pre-existing large strokes with a poor prognosis. Patients may need moved to a local cardiothoracic centre perhaps under cardiology to have further assessment before any surgical intervention.
Introduction
Potential Infective agents Details Streptococcus viridans (alpha haemolytic) a low virulence organism seen where there is a history of rheumatic fever Staphylococcus epidermidis Drug addicts and IV drug abusers have a tendency to RIGHT sided valve lesions particularly. Staphylococcus aureus causes a much more aggressive disease e.g. early following surgery especially to the heart or valve replacement. Coxiella burnetii (Q fever) Enterococci and other Gram negative bacteria HACEK Haemophilus sp, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae Risks
Markers of severity
Clinical Findings
Investigations
Definite infective endocarditis
Pathological criteria
Major criteria
Minor criteria
Complications
Management of endocarditis