Infective endocarditis resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Farman Khan, MD, MRCP [2]; Mohamed Moubarak, M.D. [3]

Definition

Infection of the endothelium of the heart including but not limited to the valves. It can be either acute or subacute. Acute bacterial endocarditis is defined as Infection of normal heart valves with a virulent organism like S. aureus, Group A or other beta-hemolytic streptococci, Streptococcus pneumoniae. Subacute bacterial endocarditis is an indolent infection of abnormal valves with less virulent organism like Streptococcus viridans.

Criteria	Definite Infective Endocarditis According to Modified Duke Criteria
Pathological Criteria	Microorganisms demonstrated by culture or histological examination of a vegetation Pathological lesions; vegetation or intracardiac abscess confirmed by histological examination showing active endocarditis
Clinical Criteria	2 major criteria; or 1 major criterion and 3 minor criteria; or 5 minor criteria
Possible IE	1 major criterion and 1 minor criterion; or 3 minor criteria
Rejected	Firm alternative diagnosis explaining evidence of IE; or Resolution of IE syndrome with antibiotic therapy for 4 days; or No pathological evidence of IE at surgery or autopsy, with antibiotic therapy for 4 days; or Does not meet criteria for possible IE as above

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Endocarditis can be a life-threatening condition if it is left untreated, and it must be treated as such irrespective of the causes.

Common Causes

• Streptococcus viridans
• Staphylococci
• Enterococcus

Management

Diagnostic approach

Shown below is an algorithm summarizing the approach to infective endocarditis.

Characterize the symptoms: ❑ Onset of the symptoms ❑ Acute ❑ Subacute ❑ Fever ❑ Chills ❑ Rigors ❑ Sweats ❑ Weakness ❑ Myalgias ❑ Arthralgias ❑ Anorexia ❑ Fatigue ❑ Shortness of breath ❑ Hemoptysis ❑ Sputum ❑ Cough ❑ Pleuritic chest pain ❑ Seizures ❑ Symptoms suggestive of stroke ❑ Symptoms suggestive of transient ischemic attack

Identify existing risk factors: ❑ History of rheumatic heart disease ❑ Prosthetic valves patients ❑ Intravenous drug users ❑ Previous infective endocarditis ❑ Cardiac transplant recipients with valves abnormality ❑ Congenital heart diseases ❑ Unrepaired cyanotic congenital heart diseases ❑ Completely repaired defect with prosthetic material or device ❑ Repaired with residual defects at the site or adjacent to the site of a prosthetic material

Examine the patient: Vital signs ❑ Temperature ❑ Fever ❑ Blood pressure ❑ Wide pulse pressure (sign of aortic insufficiency) ❑ Narrow pulse pressure (sign of left ventricular failure) Skin ❑ Petechiae ❑ Splinter hemorrhages ❑ Osler's nodes ❑ Janeway lesions Eyes ❑ Conjunctival hemorrhage ❑ Roth's spots in the retina Heart ❑ Heart murmur ❑ Aortic insufficiency ❑ Tricuspid regurgitation ❑ Mitral regurgitation Lungs ❑ Rales as a sign of heart failure Abdomen ❑ Reduced bowel sounds (sign of mesenteric embolization or ileus) ❑ Abdominal pain ❑ Flank pain (sign of embolus to the kidney) ❑ Left upper quadrant pain (sign of splenic infarct) ❑ Splenomegaly Extremities ❑ Janeway lesions (painless hemorrhagic cutaneous lesions on the palms and soles) ❑ Gangrene of fingers ❑ Splinter haemorrhages ❑ Osler's nodes (painful subcutaneous lesions in the distal fingers) Neurologic ❑ Full neurological exam ❑ Focal deficits (suggestive of stroke or brain abscess)

Does the patient have any of the following: ❑ Unexplained fever for more than 48 hours and high risk for infective endocarditis ❑ Congenital or acquired valvular heart disease ❑ Previous infective endocarditis ❑ Prosthetic heart valve ❑ Congenital heart malformation ❑ Immunodeficiency ❑ History of drug injection ❑ Newly diagnosed valve regurgitation

Order laboratory tests: ❑ Blood culture (at least two sets) ❑ WBC ❑ Marked leukocytosis is present ❑ Erythrocyte sedimentation rate ❑ Markedly elevated ❑ Rheumatoid factor ❑ A positive serum rheumatoid factor in 50% of patients with subacute disease ❑ BUN ❑ Cr ❑ Urinalysis ❑ EKG

❑ Order a TTE ❑ Order a TEE if one or more of the following is present ❑ Non diagnostic TTE in a suspected infective endocarditis (Class I, level of evidence B) ❑ Clinical complications (Class I, level of evidence B) ❑ Intracardiac device leads (Class I, level of evidence B) ❑ Staphylococcus aureus bacteremia without a known cause (Class IIa, level of evidence B) ❑ Prosthetic valve with persistent fever without bacteremia (Class IIa, level of evidence B) ❑ Prosthetic valve with a new murmur (Class IIa, level of evidence B) ❑ Nosocomial Staphylococcus aureus bacteremia with known extra-cardiac port of entry (Class IIb, level of evidence B)

Evaluate the Modified Duke Criteria for infective endocarditis: ❑ Two major criteria, OR ❑ One major and three minor criteria, OR ❑ Five minor criteria

❑ Consult an infectious disease specialist ❑ Consult a cardiologist ❑ Consult a cardiac surgeon

Reevaluate the patient with TTE and/or TEE ❑ Change in clinical signs and symptoms ❑ New murmur ❑ Embolism ❑ Persistent fever ❑ Heart failure ❑ Abscess ❑ Atrioventricular heart block ❑ High risk of complications ❑ Large vegetations on echocardiogram ❑ Staphylococcus, enterecoccal, or fungal infections

Modified Duke Criteria

Shown below is a table summarizing the major and minor Modified Duke Criteria.

Major criteria

Minor criteria

1- Positive Blood Culture for Infective Endocarditis ❑ Typical microorganism consistent with infective endocarditis from 2 separate blood cultures, in the absence of a primary focus: ❑ Viridans streptococci, streptococcus bovis ❑ HACEK group ❑ Community-acquired staphylococcus aureus ❑Enterococci OR ❑ Microorganisms consistent with infective endocarditis from persistently positive blood cultures defined as: ❑ At least 2 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) OR ❑ Single positive blood culture for Coxiella burnetii or anti–phase 1 IgG antibody titer >1:800|| style="font-size: 90%; padding: 0 5px; background: #DCDCDC" align=left 2-Echocardiographic evidence of endocardial involvement ❑ Oscillating intracardiac mass on valve or supporting structures, in the path of regurgitant jets, or on implanted material in the absence of an alternative anatomic explanation, or ❑ Abscess, or ❑ New partial dehiscence of prosthetic valve, or ❑ New valvular regurgitation

1- Predisposition ❑ Predisposing heart condition or intravenous drug use 2- Fever ❑ Temperature > 38.0° C (100.4° F) 3- Vascular phenomena ❑ Major arterial emboli ❑ Septic pulmonary infarcts ❑ Mycotic aneurysm ❑ Intracranial hemorrhage ❑ Conjunctival hemorrhage ❑ Janeway lesions 4- Immunologic phenomena ❑ Glomerulonephritis ❑ Osler's nodes ❑ Roth spots ❑ Rheumatoid factor 5- Microbiological evidence ❑ Positive blood culture but does not meet a major criterion as noted above OR ❑ Serological evidence of active infection with organism consistent with infectious endocarditis

Prophylactic Approach

Shown below an algorithm depicting the general prophylactic approaches of infective endocarditis based on 2014 AHA/ACC Guideline for the management of patients with valvular heart disease.

Identify high risk patients: (Class IIa, Level of evidence B) ❑ Prosthetic valves patients ❑ Previous infective endocarditis ❑ Cardiac transplant recipients with valves regurgitation due to structurally abnormal valve ❑ Congenital heart diseases ❑ Unrepaired cyanotic congenital heart diseases ❑ Completely repaired defect with prosthetic material or device ❑ Repaired with residual defects

Identify high risk procedures: ❑ Procedures on infected skin or musculoskeletal tissue ❑ Respiratory tract procedures ❑ Gastrointestinal and genitourinary procedures ❑ Patients undergoing cardiac surgery ❑ Dental procedures

❑ Decide if the patient needs prophylaxis

❑ Choose a prophylaxis regimen

❑ Infective endocarditis prophylaxis regimens

❑ Prophylaxis regimens if the patient is penicillin or pmpicillin allergic

❑ Prophylaxis regimens if the patient is penicillin or ampicillin allergic and cannot take oral medications

Do's

• Elicit a full medical history to help detecting the minor Duke criteria for the diagnosis.
• Initiate antibiotic therapy after withdrawing blood for culture (Class I, level of evidence B).
• Do a TEE intraoperatively among patients scheduled for valve surgery for infective endocarditis (Class I, level of evidence B).
• Consider ordering a cardiac CT scan when echocardiography does not provide clear details about the cardiac anatomy in the context of suspected paravalvular infections (Class IIa, level of evidence B).

Dont's

• Don`t wait for blood culture results in acute cases, or hemodynamically unstable patients, and start empirical antibiotic therapy.
• Don't administer prophylaxis for infective endocarditis in patients with valvular heart disease who are at risk infective endocarditis for procedures such as TEE, cystoscopy, esophagogastroduodenoscopy or colonoscopy without any evidence of active infection (Class III; level of evidence B).

References

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