Isolated native pulmonary valve endocarditis on a bicuspid valve with large vegetation and septic pulmonary emboli: a multimodality imaging case report

Background: Isolated pulmonary valve endocarditis (PVE) is a rare form of infective endocarditis (IE), accounting for fewer than 2% of all cases. Its presentation often mimics primary respiratory disease, and visualization of the pulmonary valve may be challenging, leading to diagnostic delay. Multimodality imaging is therefore essential for early recognition and treatment planning. Case summary: We report a 59-year-old woman with a history of colorectal cancer treated with surgery and colostomy who presented with 1 month of fever and progressive dyspnoea. Transthoracic and transoesophageal echocardiography demonstrated a bicuspid pulmonary valve with two large, highly mobile vegetations (largest 3.0 × 0.9 cm), mild-to-moderate pulmonary regurgitation, and a small perimembranous ventricular septal defect with left-to-right shunt. Chest computed tomography (CT) showed multiple segmental and subsegmental filling defects compatible with septic pulmonary emboli and signs of right ventricular strain. Blood cultures grew group D viridans streptococci. Despite 6 weeks of targeted intravenous antibiotics, she developed right-sided heart failure with persistent large vegetations. She underwent pulmonary valve replacement with a 27-mm mechanical bileaflet prosthesis and concomitant repair of the ventricular septal defect and closure of the patent foramen ovale. Follow-up imaging confirmed a well-functioning prosthetic valve with improved haemodynamics. Discussion: This case highlights the diagnostic and therapeutic value of combining echocardiography and CT in native PVE. Multimodality imaging allowed timely identification of the underlying congenital substrate, precise characterization of vegetation burden, recognition of septic pulmonary emboli, and informed surgical decision-making in accordance with current guideline-based indications for right-sided IE surgery.