Definition
A.An infection involving the cardiac valves (native or prosthetic), mural endocardium, or intracardiac devices.
B.Termed a vegetation.
C.Acute endocarditis.
1.Rapid damage to cardiac structures with extracardiac seeding; fulminant illness can develop in days to 2 weeks.
2.If untreated, can lead to death within weeks.
D.Subacute endocarditis.
1.Indolent course.
2.Slow and progressive damage to cardiac structures.
3.Gradually progressive unless associated with embolic event or ruptured mycotic aneurysm.
E.Short incubation period (<6 weeks) and long incubation period (>6 weeks) are preferred classifications.
F.Heart side used for classification.
1.Right sided—generally from intravenous (IV) drug use.
2.Left sided—more common in IV drug use and nondrug users.
Incidence
A.Uncommon; 3 to 7 per 100,000 person-years.
B.Life-threatening infection; third to fourth most common after fatal infective (IE) process after sepsis, pneumonia, and intra-abdominal abscess.
C.5% to 15% of affected patients have negative blood cultures.
Pathogenesis
A.Endothelial injury allows either direct infection or the development of a platelet and fibrin thrombus that serves as a site of bacterial attachment.
B.Primary portals of entry include:
1.Oral cavity.
2.Skin.
3.Upper respiratory tract.
4.Sites of focal infection.
C.Microorganisms adhere to endothelium, which is often abnormal or damaged. Platelets aggregate at the site.
D.If the organism is resistant to normal bactericidal activity of serum and microbicidal peptides released by platelets, proliferation will occur with formation of microcolonies. Platelet deposition is induced.
E.Tissue factor is elicited from the endothelium and causes a localized procoagulant state.
F.Fibrin deposition occurs. This together with platelet aggregation and microorganism proliferation all generate a vegetation.
1.Organisms deep within vegetation are metabolically inactive and resistant to antimicrobials.
2.Surface microorganisms are shed into the bloodstream continuously.
G.Clinical manifestations of IE are a result of cytokine release.
H.Microorganisms associated with IE are dependent on classification (see Table 10.1).
Predisposing Factors
A.IV drug use predominantly.
B.Advanced age.
C.Degenerative valve disease.
D.Prosthetic valves or other cardiac devices.
E.Chronic rheumatic heart disease (especially in developing countries).
F.Impaired immune system.
G.Hemodialysis.
H.Unrepaired cyanotic congenital heart defect.
Subjective Data
A.Common complaints/symptoms.
1.Flu-like symptoms, including fever and chills.
2.Night sweats.
3.Anorexia and weight loss.
4.Chest pain with breathing.
5.Shortness of breath.
B.Common/typical scenario.
1.Depends on the type of IE, location, and patient risk factors.
2.Fever: Common in most types of IE.
3.Physical examination findings: Can vary based on location of lesion.
4.Need to identify if there has been a recent surgery or illness.
C.Family and social history.
1.IV drug use.
D.Review of systems.
1.General: Malaise, chills, or sweats.
2.Cardiovascular: Recent surgery, dyspnea, or chest pain or pressure.
3.Respiratory: Dyspnea or cough.
4.Skin: Discoloration of fingers and toes, pain in fingers and toes, or cutaneous lesions.
5.Musculoskeletal: Generalized musculoskeletal pain.
6.Neurological: Vision changes or headache.
7.With arterial emboli, review of systems (ROS) can include:
a.Flank pain.
b.Hematuria.
c.Abdominal pain.
Physical Examination
A.Cardiac manifestations.
1.New regurgitant cardiac murmurs (85% of cases): Indicates valve involvement.
2.S3 heart sound (with heart failure).
B.Noncardiac manifestations.
1.Janeway lesions: Red spots on palms of hands or soles of feet.
2.Osler’s nodes: Red tender spots under the skin of fingers or toes.
3.Subungual hemorrhage.
4.Discoloration of skin, distal phalanges, or extremities (especially with arterial occlusion from emboli).
5.Conjunctival hemorrhage.
6.Petechiae.
Diagnostic Tests
A.Blood cultures.
1.Three sets of blood cultures.
2.Peripheral venipuncture, different sites.
3.First and third sets drawn at least 1 hour apart.
B.Other cultures.
1.Serologic testing for organisms difficult to identify by blood culture alone (i.e., Bartonella, Legionella).
2.At time of surgery, detection of pathogens from valve tissue by polymerase chain reaction (PCR) is validated.
C.Other tests.
1.Complete blood count (CBC) with differential.
2.Complete metabolic panel.
3.Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), procalcitonin (PCT).
4.Chest radiograph.
5.EKG.
a.With abscess formation, progressive heart block can occur.
D.Echocardiogram.
1.Transthoracic echocardiogram (TTE) in all suspected cases less than 12 hours after initial evaluation.
2.Transesophageal echocardiogram (TEE) in the following circumstances.
a.Inability to assess valve adequately in TTE.
b.Suspected IE but negative TTE.
c.High likelihood for IE: TEE first.
d.For recurrent IE.
e.If vegetation is noted.
f.Clinical suspicion for 3 to 5 days after initial TEE.
E.Other imaging modalities.
1.Coronary CT angiography (chest CT angiography [CTA] coronary).
a.In those undergoing surgery for IE.
b.Preoperative screening: Evaluation for central nervous system (CNS) and intra-abdominal lesions.
c.Limitations.
i.Radiation exposure.
ii.Nephrotoxicity associated with contrast dye.
iii.Lack of sensitivity to evaluate valve lesions.
2.MRI.
a.Tool to detect cerebral embolic events (typically silent) and evaluate for mycotic aneurysms.
b.Not routinely used.
F.Modified Duke criteria for diagnosis.
1.Based on clinical, laboratory, and echocardiographic findings.
a.Definite IE.
i.Two major criteria or
ii.One major criterion and three minor criteria or
iii.Five minor criteria.
b.Possible IE.
i.One major criterion and one minor criterion or.
ii.Three minor criteria.
c.Rejected.
i.Firm alterative diagnosis.
ii.Resolution of IE syndrome with antibiotic therapy less than 4 days.
iii.No pathological evidence of IE at surgery/autopsy with antibiotics less than 4 days.
iv.Does not meet the previous criteria.
2.Major criteria.
a.Positive blood culture.
i.Typical microorganisms identified on two separate blood cultures.
1)Viridans streptococci, Streptococcus bovis, HACEK group (fastidious gram-negative coccobacillary organisms. HACEK stands for Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella species), Staphylococcus aureus.
2)Community-acquired enterococci in the absence of a primary focus.
ii.Persistently positive blood culture, consistent with IE.
1)At least two positive cultures of blood samples drawn greater than 12 hours apart or all of three cultures or,
2)A majority of four or more separate cultures of blood (with first and last sample drawn at least 1 hour apart).