Endocarditis

Epidemiology/Pathophysiology

• Endocarditis is an infection of the heart valves which can present either acutely or as a chronic disease. It is a life threatening infectious disease that is difficult to diagnose with certainty in the Emergency Department.
• Intravenous drug abusers, immunocompromised patients, patients with a history of rheumatic heart disease, and patients who have undergone valve replacement are at heightened risk for developing endocarditis. Other patients at risk include those with intracardiac devices (pacemakers, defibrillators), those with a history of endocarditis, those with mitral valve prolapse and regurgitation, and patients with certain congenital heart defects.
• Streptococci are the most common cause of native valve endocarditis.
• Staph species are responsible for the majority of IVDU-related endocarditis and coagulase negative Staph is responsible for the majority of prosthetic valve endocarditis.
• Other etiologic agents include Enterococcus, Gram-negative bacteria, the HACEK organisms (Haemophilus, Acetinobacillus, Cardiobacterium, Eikenella, and Kingella species), Candida and Aspergillus.

Diagnosis and Evaluation
• Diagnosis of endocarditis has traditionally been based on clinical findings and bacteriologic criteria from blood cultures. The development and increased utilization of echocardiography has provided increased ability to diagnose endocarditis. The Duke criteria describes clinical, bacteriological and echocardiographic diagnostic criteria for endocarditis.

  History and Physical Exam
  

• Endocarditis presents with a variety of clinical complaints. The triad of fever, anemia, and a heart murmur is highly suggestive of endocarditis but is not routinely present.
• Fever, malaise and altered mental status are common historical features.
• Patients may also present with embolic sequelae, which occur in approximately 25-50% of patients with endocarditis. 65% of emboli involve the central nervous system, usually in a MCA distribution.
• Physical findings include heart murmurs, most commonly of the mitral and aortic valves. However, less than one-third of IVDU patients with endocarditis will have murmurs.
• Osler’s nodes, painful erythematous nodules found on the palmar fingertips, are rarely found. Janeway lesions, flat nontender macular areas on the palms are also rarely seen.

  Laboratory and Studies
  

• Laboratory findings include positive blood cultures as discussed above and a mild anemia. Most patients have microscopic hematuria as well.
• Echocardiography is a powerful tool to aid in the diagnosis of endocarditis.
• Transthoracic echo has a poor sensitivity (approximately 60%) but excellent specificity if vegetations are seen.
• Transesophageal echocardiography is more sensitive (>85% sensitivity) for visualization of vegetations.

  ED Management

• Blood culture results are often unavailable to the Emergency Physician and thus empiric antibiotic coverage is required. Blood cultures should be drawn before beginning antibiotics as antibiotics reduce the bacterial recovery rate of cultures by approximately one-third.
• Patients with an acute presentation of endocarditis, a history of IVDU or a prosthetic heart valve should receive vancomycin, an aminoglycoside (gentamycin), and rifampin.
  Patients with a subacute course and native heart valves should receive either penicillin and an aminoglycoside or a penicillinase-resistant penicillin (nafcillin) and an aminoglycoside.
• Occasionally, patients may require surgical therapy. Indications for surgery include severe congestive heart failure, recurrent emboli, fungal endocarditis, and failure of IV antibiotic therapy.

Table The Duke criteria for the diagnosis of endocarditis

Major Criteria

Positive blood cultures with typical microorganisms consistent with endocarditis Evidence of endocardial involvement with a positive echocardiogram or new valvular regurgitant murmur

Minor Criteria

Predisposing heart condition or IVDU Fever Vascular phenomena including emboli, Janeway lesions, pulmonary infarctions, mycotic aneurysms, or, splinter hemorrhages Immunologic phenomena including Osler’s nodes, Roth spots, glomerulonephritis Blood cultures suggestive of endocarditis but not meeting the major criteria Echocardiographic evidence suggestive of endocarditis but not meeting major criteria

The presence of 2 major criteria, 1 major criterion and 3 minor criteria, or 5 minor criteria establishes a diagnosis of endocarditis.

• Patients with conditions predisposing them to endocarditis should receive antibiotic prophylaxis prior to dental, GI, or GU procedures. Amoxicillin or erythromycin should be given 1 h before the procedure for proper prophylaxis.