Endocarditis

Background

• Consider in pts w/ unexplained fever and known risk factors
• Mitral valve most commonly affected overall; tricuspid valve most common in IVDA
• Noninfectious vegetations can arise in pts w/ malignancy and SLE
• S. aureus is single most common cause
• Blood cultures are falsely negative ~5% (think HACEK organisms)

Risk Factors

1. IVDA
   1. Tricuspid valve most commonly affected
2. Prosthetic heart valve
3. Structural heart disease
   1. Rheumatic heart disease
   2. Mitral valve prolapse
   3. Bicuspid aortic valve
4. Hemodialysis
5. HIV infection

Clinical Features

• Fever
  • Present in almost all cases
• Heart murmur
  • Preexisting murmur found in 85% of cases; new murmur only found in 5%
• CHF
  • Acute or progressive (70%)
• Embolization manifestations
  • CNS
    • MCA stroke
    • Central retinal artery occlusion
  • Pulmonary
    • PNA
    • Empyema
  • Cardiac
    • MI
    • Myocarditis
  • Bowel, renal, splenic infarcts
  • Derm
    • Osler nodes, splinter hemorrhages, Janeway lesions

Diagnosis

Inpatient diagnosis is based on the Duke's Criteria although many of the criteria are not filled in the ED. Heightened clinical suspicion is necessary even if diagnosis does not meet the official criteria.

Modified Duke Criteria

• 2 major criteria OR
• 1 major and 3 minor criteria OR
• 5 minor criteria

Major Criteria

1. Positive blood culture with typical IE microorganism, defined as one of the following:
   • Typical microorganism consistent with IE from 2 separate blood cultures, as noted below:
     • Viridans-group streptococci, or
     • Streptococcus bovis including nutritional variant strains, or
     • HACEK group, or
     • Staphylococcus aureus, or
     • Community-acquired Enterococci, in the absence of a primary focus
   • Microorganisms consistent with IE from persistently positive blood cultures defined as:
     • Two positive cultures of blood samples drawn >12 hours apart, or
     • All of 3 or a majority of 4 separate cultures of blood (with first and last sample drawn 1 hour apart)
     • Coxiella burnetii detected byone positive blood culture or IgG
2. Evidence of endocardial involvement with positive echocardiogram defined as:
   • Valvular mass or supporting structures or
   • Abscess, or
   • New disruption of a prosthetic valve or new valvular regurgitation

Minor Criteria

1. Predisposing factor: known cardiac lesion, recreational drug injection
2. Fever >38°C
3. Evidence of emboli: arterial emboli,pulmonary infarcts, Janeway lesions, conjunctival hemorrhage
4. Glomerulonephritis, Osler's nodes
5. Positive blood culture (that doesn't meet a major criterion) or serologic evidence of infection

Work-Up

1. Blood culture (from 3 separate sites)
2. CBC
   1. Staphylococcal endocarditis: Leukocytosis +/- thrombocytopenia
   2. Subacute endocarditis: WBC may be normal or elevated
3. UA
   1. Hematuria
4. ESR
   1. Elevated in >90% of cases
5. ECG
   1. Ischemia, heart block
6. CXR
   1. Pulmonary emboli, CHF
7. Ultrasound
   1. Obtain as soon as possible
   2. TEE may be required for:
      1. Prosthetic valves
      2. Difficulty obtaining clear TTE images (obesity, COPD)
      3. High clinical probability of endocarditis

Management

1. Initial stabilization
   1. CHF/cardiogenic shock (due to valvular defects)
   2. Pulmonary edema (left-sided valve rupture)
      1. Manage w/ afterload reduction
   3. Pulmonary failure (emboli)
   4. Acidosis (sepsis)
2. Antibiotics
   1. Start after blood cultures are obtained (if possible)
   2. Uncomplicated history
      1. Gentamicin 1-3mg/kg IV + (ceftriaxone or nafcillin or oxacillin or vancomycin)
   3. IVDA, congenital heart disease, already on oral antibiotic
      1. Nafcillin + gentamicin 1-3mg/kg IV + vancomycin
   4. Prosthetic heart valve
      1. Rifampin 300mg PO + gentamicin 1-3mg/kg IV + vancomycin

Disposition

• Admit all suspected cases

Complications

1. Cardiac
   1. Heart Failure
      1. Most common cause of death due to IE
   2. Perivalvular Abscess
2. Embolic
   1. CVA
   2. Blindness
   3. Painful, ischemic extremities
   4. Unusual pain sydromes (due to splenic or renal infarction)
   5. Hypoxia
   6. Paralysis
   7. MI
3. Neurologic
   1. Embolic stroke
   2. Acute encephalopathy
   3. Meningoencephalitis
   4. Purulent or aseptic meningitis
   5. Cerebral hemorrhage
   6. Seizure
4. Renal
   1. Infarction
   2. Glomerulonephritis
5. Musculoskeletal
   1. Vertebral osteomyelitis

External Links

• MDCalc - Duke Criteria

Further Reading

• NEJM -Infective Endocarditis. 2013

Source

• UpToDate
• Harwood-Nuss
• Tintinalli