Right Sided Infective Endocarditis

Infection of the tricuspid valve (about 90% of right sided cases), the pulmonary valve or right sided endocardium or device leads. It accounts for about 5 to 10% of endocarditis.

• Causes: injection drug use (the majority), central venous catheters and haemodialysis lines, pacemaker or defibrillator leads, congenital heart disease, and immunosuppression. Staphylococcus aureus causes 60 to 90% (methicillin resistant in a large share in some regions); others are Pseudomonas aeruginosa, streptococci, enterococci, Candida and polymicrobial infections.
• Mechanism: the tricuspid valve is damaged by repeated injection of particulate matter or by catheter induced trauma; infected vegetations (often large, 10 to 20 mm or more) shed septic emboli to the lungs.
• In hospital mortality is lower than for left sided disease (about 5 to 10%), but relapse and reinfection from continued injection are common, and long term mortality is substantial in those who do not enter addiction treatment.

• Fever, chills, pleuritic chest pain, cough, haemoptysis, dyspnoea, and multifocal lung infiltrates or cavities from septic emboli; often confused with pneumonia.
• Tricuspid regurgitation murmur louder on inspiration, raised jugular venous pressure with prominent v waves, pulsatile liver. Right heart failure is uncommon. Peripheral stigmata (Osler nodes, Janeway lesions, splenomegaly) are rare unless left sided infection or right to left shunt (patent foramen ovale or septal defect) is present, in which case paradoxical embolism and stroke can occur.
• Differential diagnosis: community acquired or aspiration pneumonia, tuberculosis, non-infective pulmonary embolism, septic thrombophlebitis, lung abscess, granulomatosis with polyangiitis, HIV-related pneumonia, and infected device leads.
• Complications: septic pulmonary emboli with abscess and empyema, pneumothorax, haemoptysis from pulmonary artery mycotic aneurysm, severe tricuspid regurgitation and right heart failure, bacteraemic relapse, paradoxical systemic emboli, and spread to left sided valves.

• Blood cultures: three sets from separate sites before antibiotics; persistent bacteraemia for days is typical.
• The diagnosis uses major criteria (typical organism in two separate cultures, or imaging evidence of vegetation or abscess) and minor criteria (injection drug use or other predisposition, fever of 38.0 degrees Celsius or more, pulmonary emboli, culture not meeting major criteria).
• Transthoracic echocardiography is usually sufficient for tricuspid vegetations; transoesophageal echocardiography for lead or catheter infection and to look for left sided involvement and shunt.
• CT chest: multiple peripheral nodules, some with a feeding vessel sign and cavitation, and wedge shaped infarcts.
• HIV test, hepatitis B and C serology, urine toxicology, creatinine, full blood count, CRP and chest X-ray. Venous Doppler ultrasound for septic thrombophlebitis and device assessment for lead involvement.

• Antibiotic therapy:
  • Empirical: vancomycin 30 mg/kg/day IV in 2 doses (trough 15 to 20 mg/L), adding gentamicin 3 mg/kg/day or ceftazidime 2 g IV every 8 hours if Pseudomonas is likely.
  • Methicillin susceptible Staphylococcus aureus: cloxacillin or flucloxacillin 2 g IV every 4 hours. A 2-week course is enough when all of the following hold: methicillin susceptible organism, no renal failure, no empyema or extrapulmonary metastatic infection, no left sided involvement, vegetation less than 20 mm, no severe immunosuppression (CD4 count 200 or more if HIV-positive). Otherwise treat for 4 to 6 weeks.
  • Methicillin resistant Staphylococcus aureus: vancomycin 30 to 60 mg/kg/day (trough 15 to 20 mg/L) or daptomycin 8 to 10 mg/kg IV once daily (weekly creatine kinase), for 4 to 6 weeks.
  • Other organisms: streptococci (benzylpenicillin 12 to 18 million units/day or ceftriaxone 2 g daily for 4 weeks), enterococci (ampicillin 2 g every 4 hours plus ceftriaxone 2 g every 12 hours for 6 weeks), Pseudomonas (an antipseudomonal beta lactam plus ciprofloxacin or an aminoglycoside for 6 weeks), Candida (liposomal amphotericin B 3 to 5 mg/kg/day with surgery, then fluconazole 400 to 800 mg daily).
  • Patients who cannot remain in hospital: oral completion after at least 10 days of IV therapy with cleared bacteraemia (for example linezolid 600 mg twice daily, or dalbavancin 1500 mg IV on days 1 and 8); evidence is limited and relapse is a concern.
• Surgery for:
  • Right heart failure from severe tricuspid regurgitation that does not respond to diuretics.
  • Persistent bacteraemia after 7 days of effective antibiotics, or a vegetation greater than 20 mm with recurrent pulmonary emboli despite treatment.
  • Fungal or other hard-to-eradicate organisms, concomitant left sided infection, or lead infection that needs extraction.
  • Preferred procedures: valve repair, vegetation debulking by percutaneous aspiration, or bioprosthetic replacement. Avoid valvectomy without replacement because it causes right heart failure. Operative mortality about 5%.
  • Device or catheter infection: remove the catheter or extract all leads, give effective therapy for at least 2 weeks after clearance (4 to 6 weeks for valve involvement), reimplant a new device only after at least 72 hours of negative cultures (14 days for valve disease), and use a different site.
• Pulmonary complications: drain empyema; manage haemoptysis conservatively, with bronchial or pulmonary artery embolisation for massive bleeding; avoid anticoagulation. Septic emboli usually resolve on antibiotics.
• Addiction treatment (essential to prevent recurrence): opioid agonist therapy (methadone starting at 20 to 30 mg daily with specialist titration, or buprenorphine sublingual 2 to 4 mg initially titrated to 8 to 16 mg daily), a naloxone supply (400 micrograms IM or 2 mg intranasal, given for emergencies), needle exchange, counselling and social support. Offer vaccination (hepatitis A and B, tetanus, pneumococcus). If HIV-positive, start antiretroviral therapy; test for and treat hepatitis C.
• Pregnancy: avoid gentamicin where possible; use ampicillin, cloxacillin or vancomycin; offer opioid agonist therapy and obstetric support.
• Renal impairment: adjust vancomycin by trough; avoid aminoglycosides.
• Children: vancomycin 40 mg/kg/day in 3 to 4 doses; flucloxacillin 200 mg/kg/day in 4 to 6 doses (maximum 12 g).
• Prevention: avoid unnecessary central lines, remove lines promptly, and use aseptic technique; amoxicillin 2 g orally (50 mg/kg in children) 30 to 60 minutes before dental procedures only for high risk patients (prosthetic valve, previous endocarditis, unrepaired cyanotic congenital heart disease).
• Red flags: haemoptysis, hypotension, new neurological deficit, persistent fever after 7 days, right heart failure, new left sided murmur.
• Follow up: echocardiography at completion, 1, 3 and 6 months; weekly blood cultures until negative then at 2 and 4 weeks after therapy; chest X-ray or CT at 6 weeks; addiction clinic follow up.