Isolated pulmonary valve endocarditis in a pediatric patient with down syndrome.

Background: Isolated pulmonary valve endocarditis (IPE) accounts for less than 2% of all infective endocarditis patients. It is commonly associated with several predisposing factors, including intravenous drug use (IVDU) and congenital heart disease. The most common causative pathogens of IPE are Staphylococcus aureus and Streptococcus viridans. We report a Down's syndrome patient with IPE and with no standard risk factors caused by the rare pathogen Acinetobacter spp. This led to respiratory failure and systemic infection due to septic pulmonary emboli. Early elective surgery was decided upon as the patient was no longer responding to medical therapy, and his clinical condition was worsening over time.

Case Presentation: A 15-year-old male with Down syndrome and no underlying heart defect presented with a 3-month history of episodic fever, nausea, vomiting, and diarrhea. Transthoracic echocardiography (TTE) revealed large vegetation on the pulmonary valve leaflet, another mobile mass at the pulmonary artery bifurcation, and severe pulmonary regurgitation. Serial blood cultures isolated Acinetobacter spp. Despite initial antibiotic therapy, the patient continued to have sepsis, unresolved vegetations, and developed life-threatening complications and respiratory distress, which convinced us to perform a pulmonary valve replacement surgery with a homograft. After surgery, the patient recovered and was discharged on the ninth postoperative day (POD).

Conclusion: This report highlights IPE's diagnostic and therapeutic challenges, alongside the importance of a comprehensive cardiopulmonary workup in patients with unexplained fever, sepsis, and pulmonary symptoms, even without typical risk factors. Based on the patient's aggravating condition despite medical treatment, early surgical intervention and pulmonary valve replacement were deemed crucial. However, there still needs to be a definitive guideline on when and how surgery should be performed in patients with complicated IPE, especially in pediatric patients.