18.4 Cardiovascular Infections: Infective Endocarditis, Rheumatic Fever & Rheumatic Heart Disease, Myocarditis, Pericarditis and Septic Thrombophlebitis

Why this area matters

The TOS cardiovascular area lists:

• carditis;
• endocarditis;
• pericarditis;
• thrombophlebitis;
• rheumatic heart disease.

Rheumatic heart disease remains an important cause of valvular heart disease in young Filipinos, which is why secondary prophylaxis with benzathine penicillin is a recurring public health topic. Endocarditis items test the organism that fits the host and the valve, the correct way to take blood cultures, and which patients need prophylaxis before dental work.

Infective endocarditis

• Clinical clues:
  • fever with a new regurgitant murmur;
  • splinter hemorrhages;
  • Janeway lesions, which are painless palmar or plantar macules caused by septic emboli;
  • Osler nodes, which are painful nodules on the finger pads caused by immune complexes;
  • Roth spots, which are retinal hemorrhages with pale centers;
  • splenomegaly and glomerulonephritis;
  • embolic stroke or mycotic aneurysm.
• Blood cultures: collect at least three sets from separate venipunctures before antibiotics. Persistent bacteremia is characteristic.
• Echocardiography: transthoracic echo first, and transesophageal echo for prosthetic valves or abscess.
• Modified Duke criteria:
  • Major criteria are typical organisms in two separate blood cultures and evidence of endocardial involvement on echo.
  • Minor criteria are a predisposing condition, fever of 38°C or more, vascular phenomena, immunologic phenomena and microbiologic evidence that falls short of a major criterion.
• Prophylaxis before dental procedures that manipulate the gingiva is limited to the highest-risk patients: those with prosthetic valves, previous endocarditis, certain congenital heart diseases and cardiac transplant valvulopathy. The usual regimen is amoxicillin 2 g orally 30 to 60 minutes before the procedure.

Acute rheumatic fever and rheumatic heart disease

• Cause: acute rheumatic fever follows group A streptococcal pharyngitis, but not streptococcal skin infection, usually 2 to 4 weeks later and mainly in children aged 5 to 15.
• Mechanism: antibodies against the streptococcal M protein cross-react with cardiac myosin and valve tissue. This is molecular mimicry, a type II hypersensitivity reaction.
• Pathology: Aschoff bodies (granulomas with fibrinoid necrosis) and Anitschkow (caterpillar) cells. Pancarditis is typical, and the mitral valve is affected most often.
• Jones criteria: evidence of preceding group A streptococcal infection (raised ASO or anti-DNase B titer, or a positive throat culture or antigen test), plus either two major criteria or one major and two minor criteria.

• Course: acute disease causes mitral regurgitation. Repeated attacks cause rheumatic heart disease with mitral stenosis, often with atrial fibrillation, stroke and pulmonary hypertension; the risk is higher in pregnancy.
• Primary prevention is treatment of streptococcal pharyngitis with penicillin or amoxicillin for 10 days.
• Secondary prophylaxis is benzathine penicillin G 1.2 million units IM every 3 to 4 weeks. Its duration depends on carditis and residual valve disease:
  • no carditis: at least 5 years or until age 21, whichever is longer;
  • carditis without residual valve disease: at least 10 years or until age 21;
  • persistent valve disease: at least 10 years or until age 40, sometimes for life.

Myocarditis

• Viral causes: most cases follow viral infection, classically Coxsackie B virus. Adenovirus, parvovirus B19, HHV-6, influenza, SARS-CoV-2 and dengue are other causes.
• Toxic causes: diphtheria toxin causes myocarditis and conduction block 1 to 2 weeks after the throat infection.
• Parasitic causes elsewhere include Trypanosoma cruzi (Chagas disease in Latin America) and Trichinella.
• Presentation: heart failure, arrhythmias or chest pain after a viral prodrome, with raised troponin.
• Diagnosis: cardiac MRI or endomyocardial biopsy, which shows lymphocytic infiltrates with myocyte necrosis.

Pericarditis

Septic thrombophlebitis

• Catheter-related suppurative thrombophlebitis: usually S. aureus. Remove the line.
• Lemierre syndrome: after pharyngitis, Fusobacterium necrophorum causes septic thrombophlebitis of the internal jugular vein, with septic emboli to the lungs.
• Pylephlebitis: septic thrombosis of the portal vein after appendicitis or diverticulitis, causing liver abscesses.
• Septic pelvic thrombophlebitis: fever after cesarean delivery that persists despite antibiotics.
• Cavernous sinus thrombosis: usually S. aureus spreading from the "danger triangle" of the face.