Endocarditis : Diagnosis, Pathophysiology And Treatment

Thursday, May 15th 2014. | Disease

Endocarditis : Diagnosis, Pathophysiology and Treatment

Endocarditis is an inflammation of the endocardium, the membrane lining the chambers of the heart and covering the cusps of the heart valves. Infective endocarditis (IE) refers to infection of the heart valves by microorganisms.
Endocarditis is often referred to as either acute or subacute depending on the clinical presentation. Acute bacterial endocarditis is a fulminating infection associated with high fevers, systemic toxicity, and death within a few days to weeks if untreated. Subacute infectious endocarditis is a more indolent infection, usually occurring in a setting of prior valvular heart disease.
Pathophysiology of Endocarditis :
  • Most patients with IE have risk factors, such as preexisting cardiac valve abnormalities.
  • Most types of structural heart disease resulting in turbulence of blood flow will increase the risk for IE. Some of the most important include the following:
  1. Presence of a prosthetic valve (400-fold increased risk)
  2. Previous endocarditis (400-fold increased risk)
  3. Complex cyanotic congenital heart disease (e.g., single ventricle states)
  4. Surgically constructed systemic pulmonary shunts or conduits
  5. Acquired valvular dysfunction (e.g., rheumatic heart disease)
  6. Hypertrophic cardiomyopathy
  7. Mitral valve prolapse with regurgitation
  8. Intravenous drug abuse
  • Three groups of organisms cause most cases of IE: streptococci (55% to 62%), staphylococci (25% to 35%), and enterococci (5% to 18%) 
  • Important clinical signs, especially prevalent in subacute illness, may include the following peripheral manifestations (“stigmata”) of endocarditis:

  1. Osler nodes

  1. Janeway lesions
  2. Splinter hemorrhages
  3. Petechiae
  4. Clubbing of the fingers
  5. Roth spots
  6. Emboli
  7. Without appropriate antimicrobial therapy and surgery IE is usually fatal. With proper management, recovery can be expected in most patients.
Factors associated with increased mortality include the following:
Congestive heart failure
Culture-negative endocarditis
Endocarditis caused by resistant organisms such as fungi and gram-negative bacteria
Left-sided endocarditis caused by Staphylococcus aureus
Prosthetic valve endocarditis
Treatment of Endocarditis :
  • The most important approach to treatment of IE includes isolation of the infecting pathogen and determination of antimicrobial susceptibilities, followed by high-dose, bactericidal antibiotics for an extended period.
  • For most patients 4 to 6 weeks of therapy are required.
  • Specific recommendations for treating IE caused by the most common organisms are discussed in this chapter.
  • β-Lactam antimicrobials, such as penicillin G, nafcillin, and ampicillin, remain the drugs of choice for streptococcal, staphylococcal, and enterococcal endocarditis, respectively.
  • For some pathogens, such as enterococci, the use of synergistic antimicrobial combinations (including an aminoglycoside) is essential to obtain a bactericidal effect.
  • Surgery is an important adjunct to management of endocarditis in certain patients. In most cases, valvectomy and valve replacement are performed to remove infected tissues and restore hemodynamic function. The most important indications for surgical intervention in the past have been heart failure in left-sided IE and persistent infections in right-sided IE.

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