Classification
- Non-infective: uncommon
- Thrombotic –deposition of fibrin on (L>R) valve in small sterile vegetations (1-5 mm). May be a history of valve damage secondary to Rh F or ischaemia.
- Libman-Sacks – Atypical verrucous endocarditis at autopsy in ~40% of SLE pats.
- Malignancy
- Infective: Much more common. Used to be split into acute (normal valves) and subacute (abnormal or prosthetic valves, insidious course). Now more often classified into:
- Native valve (NVE)
- Prosthetic valve (PVE)
The rest of the article concerns
Infective Endocarditis.
Risk Factors
- Heart disease
- Valvular: e.g. Rh F, MV prolapse
- Structural: e.g. VSD, congenital heart disease
- IVDU – 30x risk of general pop. TV>MV>AV
- Dental – Poor hygiene, procedures (even brushing)
- Recent instrumentation (esp GI, GU).
- Renal dialysis
- Others DM, HIV, M>F, skin infections
Causes
- Native valve _
- Non-IVDU: Strep ~35% (mainly viridans<60y, bovis >60y), S. aureus ~30%, S. epidermidis ~10%, Enterococci <10%, culture negative ~10%
- IVDU: S. aureus >70%, Strep 15% (mainly viridans), Candida, polymicrobial
- Prosthetic valve – Early (contaminant): S.epidermidis (aka coagulase neg), S.aureus
- Late: Strep viridans, S.aureus, S.epidermidis, Enterococci (sim to NVE)
- Rarer cases of IE (<10%): HACEK (Haemophilus, Acinobacillus, Cardiobacterium, Eikenella & Kingella spp.), Gram-ve bacilli (e.g. Pseudomonas), fungi (rare).
Pathogenesis
- Initial endothelial damage → platelet-fibrin deposits (non-bacterial thrombotic endocarditis → microbial invasion → infected vegetations → local damage (valve dysfunction & even conduction disturbance) & embolisation (bacteraemia, distant ischaemia/infarction by small vessel occlusion)
Clinical features
- Infection: Fever, rigors, night sweats, malaise, wt loss, anaemia, late splenomegaly & clubbing
- Cardiac lesions: New/changed murmur (L>R). AV & bundle blocks (aortic root abscess). CCF.
- Immune complex deposition: Vasculitis may affect any vessel. Microscopic haematuria is common; GN & ARF. Roth spots (boat-shaped retinal haemorrhage with pale centre); splinter haemorrhages, Osler’s nodes (tender) Janeway lesions (painless) are pathognomonic.
- Embolic phenomena: Emboli may cause infarction/abscesses in the relevant organ e.g. brain, heart, kidney, spleen, GI tract. In right sided endocarditis, pulmonary abscesses may occur.
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Prosthetic valve endocarditis may be sub-acute with absence of classical signs.
Diagnosis
- _Bloods: FBC (haemolytic anaemia, ↑WCC), high ESR/CRP. Also check U&E, Mg2+, LFTs. Serology (C3, C4, RF,ANA), cultures (3 sets at different sites ±times, >90% Dx from first 2; <10% neg).
- Urinalysis microscopic haematuria.
- CXR (cardiomegaly,pneumonia,APO) and ECG (RBBB, prolonged PR interval) at regular intervals.
- Echocardiography Transoesophageal more sensitive than transthoracic and better for visualising mitral lesions and possible development of aortic root abscess. Still ~10% false neg rate with repeated TOE.
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Definitive diagnosis is based on the Duke criteria: 2 major OR 1 major and 3 minor OR all 5 minor criteria:
- Major Criteria: Positive (typical x 2 or persistent) blood culture, positive ECHO (vegetation, abscess, dehisced valve)
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Minor criteria: Predisposition (cardiac lesion; IV drug abuse), fever >38°C, vascular/immunological signs, positive blood culture that don’t meet major criteria, positive ECHO that doesn’t meet major criteria
Management
- Liaise early with a microbiologist and a cardiologist.
- Resus if respiratory or CVS compromise
- Antibiotics: for 2-6weeks
Empirical IV therapy: benzylpenicillin 1.8g q4h + gentamicin 4-6mg/kg od + flucloxacillin 2g q6h IV. If penicillin sensitivity, prosthetic valve, acquired in hospital, or community MRSA suspected use vancomycin 1g q12h + gentamicin 4-6mg/kg od - Consider surgery if: CCF, valvular obstruction; repeated emboli; fungal endocarditis; persistent bacteraemia; S.aureus, myocardial abscess; unstable infected prosthetic valve.
- Anticoagulation not proven to prevent embolic events and risk of ICH. Stop in S.aureus (particularly high risk) endocarditis, consider stopping in other cases.
Prognosis
- Overall mort=20-25%. Prosthetic (50%)>Native. Better if R sided IVDU (10%). Worse if CCF (>50%). Also org-dep: 50% with pseudomonas, >30% with staph; 14% with bowel orgs; 6% with sensitive streptococci. Relapse <10% with native valves, sl higher with prosthetic.
Prophylaxis
-
No evidence for benefit. Decision to give based on risk from cardiac lesion & proc. If both high then prophylaxis. If only 1 is high prophylaxis should probably be given else not.
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Cardiac Lesions
- High risk: prosthetic valves, cyanotic CHD, surgical L→R shunts, MVP+MR, prev. endocarditis
- Medium risk: Other cong. heart disease, acq. valve disease, HOCM, surg sys-pulm shunts.
- Procedures
- High Risk -Dental (extraction, periodontal surgery, re-implantation), resp tract surgery or biopsy, GU (prostatic surgery, cystoscopy, circ, surg if infection present), GI (variceal surgery, ERCP, Biliary tract surgery, Intestinal surgery but not endoscopy)
- (Other areas – I&D of abscess – use antibiotics appropriate for local infection.)
- Medium risk: Other dental work that might cause ‘significant bleeding’,
- High Risk -Dental (extraction, periodontal surgery, re-implantation), resp tract surgery or biopsy, GU (prostatic surgery, cystoscopy, circ, surg if infection present), GI (variceal surgery, ERCP, Biliary tract surgery, Intestinal surgery but not endoscopy)
- Antibiotic regimes
- Dental/RT – amoxycillin 2g IV immed prior to proc OR PO 1 hr pre-proc.
- If penicillin sensitive: clindamycin 600mg IV 20mins pre-proc OR PO 1hr pre-proc.
- GU/GIT – gentamicin 2mg/kg IV immed prior to proc PLUS amoxycillin 2g IV immed prior to proc OR PO 1 hr pre-proc. and 1g PO 6hrs post proc.
- If penicillin sensitive: gentamicin plus vancomycin 1g IV infused pre-proc.
- Dental/RT – amoxycillin 2g IV immed prior to proc OR PO 1 hr pre-proc.