EM Notes – Endocarditis

Classification

  1. Non-infective: uncommon
    1. 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.
    2. Libman-Sacks – Atypical verrucous endocarditis at autopsy in ~40% of SLE pats.
    3. Malignancy
  2. 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:
    1. Native valve (NVE)
    2. Prosthetic valve (PVE)

The rest of the article concerns

Infective Endocarditis.

Risk Factors

  1. Heart disease
    1. Valvular: e.g. Rh F, MV prolapse
    2. Structural: e.g. VSD, congenital heart disease
  2. IVDU – 30x risk of general pop. TV>MV>AV
  3. Dental – Poor hygiene, procedures (even brushing)
  4. Recent instrumentation (esp GI, GU).
  5. Renal dialysis
  6. Others DM, HIV, M>F, skin infections

Causes

  1. Native valve _
    1. Non-IVDU: Strep ~35% (mainly viridans<60y, bovis >60y), S. aureus ~30%, S. epidermidis ~10%, Enterococci <10%, culture negative ~10%
    2. IVDU: S. aureus >70%, Strep 15% (mainly viridans), Candida, polymicrobial
  2. Prosthetic valveEarly (contaminant): S.epidermidis (aka coagulase neg), S.aureus
  3. Late: Strep viridans, S.aureus, S.epidermidis, Enterococci (sim to NVE)
  4. Rarer cases of IE (<10%): HACEK (Haemophilus, Acinobacillus, Cardiobacterium, Eikenella & Kingella spp.), Gram-ve bacilli (e.g. Pseudomonas), fungi (rare).

Pathogenesis

  1. 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

  1. Infection: Fever, rigors, night sweats, malaise, wt loss, anaemia, late splenomegaly & clubbing
  2. Cardiac lesions: New/changed murmur (L>R). AV & bundle blocks (aortic root abscess). CCF.
  3. 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.
  4. 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.

  5. Prosthetic valve endocarditis may be sub-acute with absence of classical signs.

Diagnosis

  1. _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).
  2. Urinalysis microscopic haematuria.
  3. CXR (cardiomegaly,pneumonia,APO) and ECG (RBBB, prolonged PR interval) at regular intervals.
  4. 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.
  5. Definitive diagnosis is based on the Duke criteria: 2 major OR 1 major and 3 minor OR all 5 minor criteria:

    1. Major Criteria: Positive (typical x 2 or persistent) blood culture, positive ECHO (vegetation, abscess, dehisced valve)

    2. 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

  1. Liaise early with a microbiologist and a cardiologist.
  2. Resus if respiratory or CVS compromise
  3. 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
  4. Consider surgery if: CCF, valvular obstruction; repeated emboli; fungal endocarditis; persistent bacteraemia; S.aureus, myocardial abscess; unstable infected prosthetic valve.
  5. 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

  1. 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

  1. 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.

  2. Cardiac Lesions

    1. High risk: prosthetic valves, cyanotic CHD, surgical L→R shunts, MVP+MR, prev. endocarditis
    2. Medium risk: Other cong. heart disease, acq. valve disease, HOCM, surg sys-pulm shunts.
  3. Procedures
    1. 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)
      1. (Other areas – I&D of abscess – use antibiotics appropriate for local infection.)
    2. Medium risk: Other dental work that might cause ‘significant bleeding’,
  4. Antibiotic regimes
    1. Dental/RTamoxycillin 2g IV immed prior to proc OR PO 1 hr pre-proc.
      1. If penicillin sensitive: clindamycin 600mg IV 20mins pre-proc OR PO 1hr pre-proc.
    2. GU/GITgentamicin 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.
      1. If penicillin sensitive: gentamicin plus vancomycin 1g IV infused pre-proc.
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