150. Infective Endocarditis


Mitral valve MC valve. Then aortic > tricupsid > pulmonic. Occurs due to either cardiac structural abnormality (congenital or acquired) or other risk factor (IVDA, indwelling catheter, poor dental hygiene, HIV). Other RF: renal disease, DM, lower SES, age > 60, male.

Native valves: MC structural abnormality: mitral valve prolapse. Others: bicuspid aortic valve, aortic stenosis, rheumatic heart disease (leading cause in developing world). IVDA: usually tricuspid valve or right sided heart valves. Increased rate of reoccurrence. Risk 2-5% every year. Cocaine in particular increases risk. Staph aureus MCC (30% in non-IVDA, >50% in IVDA), then strep (non-viridans and viridans) and enterococci. IVDA can also have gram-negative bacilli.

Prosthetic valves: no difference in mechanical vs bioprosthetic. Early valve endocarditis in first 60 days after surgery (higher mortality, usually coag neg staph) vs late valve endocarditis (usually staph aureus). Staph epidermis MCC; Aspergillus and Candida also involved.


Fever > 38C in 90% overall, >98% in IVDA. Other nonspecific symptoms: N/V, fatigue, malaise.

Regurgitation murmur: reported in > 85% of cases. 70% have acute or progressive CHF.

Embolization (22-50%): stroke (MCA distribution MC), retinal artery embolism (monocular blindness), pulmonary emboli, splenic / renal infarction (microscopic hematuria seen in 50% due to glumerulonephritis), mesenteric ischemia, acute limb ischemia.

Skin findings: Osler nodes (small, tender subq nodules on pads of fingers or toes), Janeway lesions (painless hemorrhagic plaques on palms or soles), petechiae, splinter or sublingual hemorrhages.

Roth Spots – retinal hemorrhages: pale with red halo.

If suspicious, will have to admit for culture, echocardiogram, and clinical observation. No clinical prediction rules.

Duke Criteria: Two major or 1 major + 3 minor or 5 minor. MDCalc Link.

Major: Positive blood culture (Strep bovid, Viridans, HACEK (H.aphrophilus, Actinobacillus, Cardiobacterium, Eikenlla, Kingella) ; Staph aureus/enterococci without other source; Coxiella burnetti or anti phase I immunoglobulin G antibody >1:800); Positive echocardiogram (intracardiac mass on valve or supporting structure; abscess; new partial dehiscence of prosthetic valve); New valvular regugitation

Minor: Predisposition; Fever > 38C; Vascular phenomena (arterial emboli, septic pumonary conjunctival hemorrhages, Janeway lesions); Immunologic phenomena (glomerulonephritis, Osler nodes, Roth spots, Rheumatoid fever); Microbiologic evidence (positive BC that does meet major criteria).


3 sets of blood cultures needed; ideally 1 hr between first and last one.

Lab: Anemia present in 70-90% of cases, elevated ESR in 90%. Also hematuria, CRP, and procalcitonin.

TEE > TTE. TTE 88-94% in IVDA, more sensitive in large lesions, right sided lesions and favorable patient habitus. TEE always recommended in prosthetic valves, intermediate/high clinical suspicion.


No anticoagulation for native valves. Maintain anticoagulation for prosthetic valves.

Usually penillinase-resistant PCN or cephalosporin (Ceftriaxone, Nafcillin, Oxacillin, or Vancomycin) + aminoglycoside (Gentamicin, Tobramycin). Vancomycin added for IVDA, congenital heart dx, pts currently on oral abx, nosocomial, suspected MRSA – basically everyone). Just think Vancomycin + Gentamicin. Start immediately after cultures obtained if high clinical suspicion. New articles on oral cipro + rifampin for IVDA so that they don’t need PICC line.

Most require 4-6 weeks of tx. Some require valve replacement.


Not routine: mitral valve prolapse, HCOM, physiologic murmurs, prior CABG, previous surgical repair of atrial septal defect, VSD, PDA.

High risk: prosthetic valves, hx/o previous infective endocarditis, unprepared cyanotic congenital heart dx, repaired congenital defect with prosthetic material, cardiac transplants recipients who develop valve regurg due to structurally abnormal valve, repaired congenital heart defects with residual abnormality.

Recommended procedures: dental procedures involving gingival, periodical tooth, or oral mucosa manipulation. Lower recommendation (IIb) for infected skin, skin structure or musculoskeletal tissue. Low risk of bacteremia with abscess I&D. For other procedures, several organizations (AHA included )have stated no prophylaxis needed (GU, respiratory, GI). Still reasonable for tonsillectomy/adenoidectomy.

Treatment: IV: Vancomycin or Clindamycin if MRSA suspected with infected skin. Dental procedures: amoxicillin, cephalexin, clindamycin, or azithromycin. IV ampicillin, cefazolin, ceftriaxone, or clindamycin. Oral given 1 hour prior to procedure.

Clinical Cases


Tintinalli, Seventh Edition, Chapter 150: Infective Endocarditis

Crashing Patient, Scott Weingart, Endocarditis and Valvular Heart Disease

Circulation, 2007, Prevention of Infective Endocarditis: Guidelines from the American Heart Association

Circulation, 2000, Risk Factors for Infective Endocarditis

Life in the Fast Lane, Critical Care Compendium, Infective Endocarditis, Reviewed 3/5/14

150. Infective Endocarditis

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