An approach to the diagnostic use of echocardiography

Infective Endocarditis Darren DeWalt 1/00

Incidence

1.7-4 per 100,000 persons per year
15,000 to 20,000 new cases each year

Microbiology

Native valve endocarditis

Streptococci 50%
Viridans 35
S. bovis 15
Enterococci 10
Staphylococci 25
S. aureus 23
Coag neg 2
Diphtheroids --
Gram-negative bacilli 6
Fungi 1
Other and culture neg 8

HACEK organisms: Haemophilus sp., Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corodens, and Kingella sp. These are fastidious organisms which are part of the oropharyngeal flora. These organisms require prolonged incubation and appropriate subcultures.

Diagnostic Criteria

Duke criteria: definite IE clinical criteria (using special definitions). Patient must meet two major criteria, or one major and three minor criteria, or five minor criteria. The additional minor criteria are part of the "modified Duke criteria" by Lamas and Eykyn.

Major

Criteria

Positive blood culture for infective endocarditis Typical microorganism for infective endocarditis Viridans streptococci, S. bovis, HACEK group, or Community-acquired S. aureus or enterococci, in the absence of a primary focus, or Persistently positive blood culture, defined as microorganism consistent with infective endocarditis from Blood cultures drawn more than 12 hours apart, or

All of 3, or majority of 4 or more separate blood cultures,

With first and last drawn at least 1 hour apart

Evidence of Endocardial Involvement Positive echocardiogram for infective endocarditis Oscillating intracardiac mass on valve or supporting structures or in the path of regurgitant jets, or on iatrogenic devices, in the absence of an alternating explanation, or

Abscess, or

New partial dehiscence of prosthetic valve, or

New valvular regurgitation

Minor

Criteria

Predisposition:

Fever:

Vascular phenomenon:

Immunologic phenomenon:

Echocardiogram:

Microbiologic evidence:

Predisposing heart condition or IVDA

>= 38.0 C

Arterial embolism, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, Janeway lesions

Glomerulonephritis, Olser nodes, Roth spots, Rheumatoid factor

Consistent with infective endocarditis but not meeting major criteria

Positive blood culture but not meeting major criterion above, or serologic evidence of active infection with organism consistent with infective endocarditis

Additional

Minor

Criteria

Newly diagnosed splenomegaly

Newly diagnosed clubbing

Splinter hemorrhages

Petechiae

High erythrocyte sedimentation rate, defined as more than one and one-half times the upper limit of normal (ESR>30mm/hr for patients <60 yrs; ESR>50 for those >60 yrs) High C-reactive protein level, defined as >100 mg/l

Microscopic hematuria

Central nonfeeding venous lines

Peripheral venous lines

Possible IE:

Findings consistent with IE that fall short of "definite" but not "rejected".

Rejected:

Firm alternate diagnosis for manifestations of endocarditis, or

Resolution of manifestations of endocarditis with antibiotic therapy for <= 4 days, or no pathological evidence of IE at surgery or autopsy, after antibiotic therapy for <= 4 days

Physical Findings

Classic Syndrome: Fever, anemia, heart murmur, embolic phenomena (FAME)

1. Fever: 90% of patients will have fever

2. Heart Murmur: 85% will have a murmur at some point during the course. It may not be audible at the initial evaluation, which suggests the need for serial physical exams. 90% of patients with a new regurgitant murmur develop CHF.

3. Cutaneous:

· Petechaie are the most common finding—20-40% of patients.

· Osler’s nodes: erythematous, painful subcutaneous nodules in the finger and toe pads--10-25%. Immunologic phenomena. These are also found in SLE, marantic endocarditis, and disseminated gonococcal infection.

· Splinter hemorrhages: 15%

· Janeway’s lesions: nontender, hemorrhagic macules on palms and soles--<10%. These represent septic microemboli.

4. Ophthomologic: · Conjunctival petechaie—common.

· Roth spot: oval hemorrhage with a pale center on the fundus--<5%

5. Splenomegaly: 25-60% 6. Musculoskeletal:
· Back pain: the presenting complaint in 5-10% of cases.

· Arthritis: Can be both immunologic and septic.

Laboratory Tests/Imaging 1. Blood Cultures: Positive in >99% if prior to antibiotics. · Prior to starting antibiotics, get at least 2 blood cultures from different sites. If possible get 4 cultures with the first and last > 1 hour apart. · If you have a high suspicion for IE, have the lab check for HACEK organsims. 2. CBC: · Anemia: present in 50-80%--normochromic, normocytic.

· Leukocytosis: usually present, more frequent with staph or pneumococcal IE.

· Thrombocytopenia: unusual.

3. ESR: Almost always elevated but non-specific. 4. CRP: Commonly elevated, non-specific. 5. Urinalysis: microscopic hematuria and proteinuria are the most common findings and are secondary to immune complex injury. · May also see pyuria (metastatic infection), cellular casts (immune complex mediated glomerulonephritis), or gross hematuria (infarction). 6. Rheumatoid Factor: positive in 50%. Resolves after appropriate treatment.
7. CXR: Peripheral nodular densities represent metastatic lesions. Effusions are present in 75% of patients. May also see cavitation or atelectasis. 8. Echocardiogram: Necessary to look for vegetations, myocardial abscess, and valve competence and stability. May help assess risk for embolism. MV lesions are most likely to embolize and lesions >10mm are more likely to embolize.
· TTE: less sensitive (40-70%) for vegetations, but noninvasive.

· TEE: 90-95% sensitive for a vegetation.

See figure below for possible algorithm.

An approach to the diagnostic use of echocardiography. *High-risk echocardiographic features include large and/or mobile vegetations, valvular insufficiency, suggestion of perivalvular extension, or secondary ventricular dysfunction (see text). # For example, a patient with fever and a previously known heart murmur and no other stigmata of IE. + High initial patient risks include prosthetic heart valves, many congenital heart diseases, previous endocarditis, new murmur, heart failure, or other stigmata of endocarditis. Rx indicates antibiotic treatment for endocarditis.

Complications

1. Cardiac: · CHF: The most frequent complication. Usually secondary to valvular insufficiency, and if difficult to control and/or not responding to treatment, it is an indication for surgery. In one outcomes study, 1/3 of patients required valve replacement during the acute phase of IE and another 1/3 required replacement within 2 years of infection. · Valve ring abscess: 30% of patients, more common in aortic area and with prosthetic valves. · Myocardial abscess: occurs secondary to emboli in coronaries · Conduction abnormalities: usually secondary to paravalvular abscess. This is important to monitor for with serial EKG and telemetry. 2. Neurologic: 20-40% of patients with IE develops neurologic complications. Usually presents like stroke but may be personality changes, delerium or seizures. · Mycotic aneurysm: secondary to septic emboli—catastrophic if ruptures.
Some authors suggest that any patient with localized or severe headache, "sterile" meningitis, or focal neurologic signs get an arteriogram.
· Brain abscess: also secondary to septic emboli. · CSF findings: abnormal in 70% of patients with neurologic complaints. Most commonly has a mild pleocytosis suggesting aseptic meningitis. 3. Renal disease: · Embolism or infarction occurs in 2/3 of cases. · Glomerular disease secondary to immune complex deposition is common, but usually not serious · Tubular damage or interstitial nephritis may occur during antibiotic treatment with aminoglycosides or penicillins. 4. Persistent Fever:

Most patients defervesce within 7 days

If fever lasts >14 days, must search for other causes.

Myocardial abscess was present in 27% of patients with persistent fever.

Metastatic abscess: splenic and renal are the most common, but may have septic arthritis, brain abscess or pulmonary emboli.

Catheter infection

Drug fever

Interstitial nephritis

Indications for surgery

Severe refractory CHF
Recurrent systemic emboli
Large vegetations
Refractory infection
Progressive intracardiac infection
Prosthetic valve dehiscence
Persistent bacteremia
Heart block
Bundle branch block

References Bayer AS, Bolger AF, et al. Diagnosis and management of infective endocarditis and its complications. Circulation. 98: 2936-48, 1998.

Cobbs CG, Hoesley CJ. Endocarditis at the millennium. Journal of Infectious Diseases. 179(suppl 2): S360-5, 1999.

Cunha BA, Gill MV, Lazar JM. Acute infective endocarditis. Infectious Disease Clinics of North America. 10(4): 811-33, 1996.

Farmer JA, Torre G. Endocarditis. Current Opinion in Cardiology. 12: 123-30, 1997.

Harris PS, Cobbs CG. Cardiac, cerebral and vascular complications of infective endocarditis. Cardiology Clinics. 14(3): 437-50, 1996.

Kemp WE, Citrin B, Byrd BF. Echocardiography in infective endocarditis. Southern Medical Journal. 92(8): 744-54, 1999.

Saccente M, Cobbs CG. Clinical approach to infective endocarditis. Cardiology Clinics. 14(3): 351-62, 1996.

Stamboulian D, Carbone E. Recognition, management and prophylaxis of endocarditis. Drugs. 54(5): 730-44, 1997.