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, primarily bacteria.
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 days to weeks if untreated. Subacute infectious endocarditis is a more indolent infection, usually occurring in a setting of prior valvular heart disease.
Most patients with IE have risk factors, such as preexisting cardiac valve abnormalities. Many types of structural heart disease resulting in turbulence of blood flow will increase the risk for IE. Some of the most important risk factors include the following:
✓ Highest risk: presence of a prosthetic valve or previous endocarditis
✓ Congenital heart disease, chronic intravenous access, diabetes mellitus, healthcare-related exposure, acquired valvular dysfunction (eg, rheumatic heart disease), hypertrophic cardiomyopathy, mitral valve prolapse with regurgitation, and intravenous (IV) drug abuse.
Three groups of organisms cause most cases of IE: streptococci, staphylococci, and enterococci (Table 37–1).
TABLE 37–1Etiologic Organisms in Infective Endocarditisa |Favorite Table|Download (.pdf) TABLE 37–1 Etiologic Organisms in Infective Endocarditisa
|Agent ||Percentage of Cases |
|Staphylococci ||30–70 |
| Coagulase positive ||20–68 |
| Coagulase negative ||3–26 |
|Streptococci ||9–38 |
| Viridans streptococci ||10–28 |
| Other streptococci ||3–14 |
|Enterococci ||5–18 |
|Gram-negative aerobic bacilli ||1.5–13 |
|Fungi ||1–9 |
|Miscellaneous bacteria ||<5 |
|Mixed infections ||1–2 |
|“Culture negative” ||<5–17 |
The clinical presentation of patients with IE is highly variable and nonspecific (Table 37–2). Fever is the most common finding. The mitral and aortic valves are most often affected.
Important clinical signs, especially prevalent in subacute illness, may include the following peripheral manifestations (“stigmata”) of endocarditis: Osler nodes, Janeway lesions, splinter hemorrhages, petechiae, clubbing of the fingers, Roth’s spots, and emboli.
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 (PVE).
Ninety percent to 90% to 95% of patients with IE have a positive blood culture. Anemia, leukocytosis, and thrombocytopenia may be present. The erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) may be elevated in approximately 60% of patients.
Transesophageal echocardiography is important in identifying and localizing valvular lesions in patients suspected of having IE. It is more sensitive for detecting vegetations (85%–90%), compared with transthoracic echocardiography (58%–75%).
The Modified Duke criteria, encompassing major findings of persistent bacteremia and echocardiographic findings and other minor findings, are used to categorize ...
Pop-up div Successfully Displayed
This div only appears when the trigger link is hovered over.
Otherwise it is hidden from view.