Isolated Native Pulmonary Valve Endocarditis on A Bicuspid Valve with Large Vegetation and Septic Pulmonary Emboli: A multimodality Imaging Case Report

Abstract Background Isolated pulmonary valve endocarditis (PVE) is a rare entity accounting for less than 2% of all cases of infective endocarditis (IE). Its nonspecific symptoms often mimic respiratory disease, leading to diagnostic delay. Echocardiography is the mainstay for diagnosis, but pulmonary valve visualization can be suboptimal in transthoracic studies, necessitating multimodality imaging. Case Presentation We report a 59-year-old woman with a history of colorectal cancer treated surgically with colostomy, who presented with one month of persistent fever and progressive dyspnea. Transthoracic and transesophageal echocardiography revealed a bicuspid pulmonary valve with two large, mobile vegetations (largest 3.0 × 0.9 cm) and mild-moderate pulmonary regurgitation. A small perimembranous ventricular septal defect with left-to-right shunt was also present. Chest CT demonstrated multiple bilateral cavitary nodules consistent with septic pulmonary emboli and features of right ventricular strain. Blood cultures grew a group D streptococcus belonging to the viridans group. The patient received six weeks of targeted intravenous antibiotics but developed right-sided heart failure with persistent large vegetations, prompting surgical intervention. She underwent pulmonary valve replacement with a 27-mm mechanical bileaflet prosthesis and concomitant repair of the ventricular septal defect and patent foramen ovale. Follow-up imaging confirmed a well-functioning prosthetic valve with improved hemodynamics. Discussion This case underscores the crucial role of multimodality imaging, particularly echocardiography and CT, in the early detection and comprehensive management of native PVE and its embolic complications. Integration of these modalities is indispensable for accurate diagnosis, surgical decision-making, and post-operative follow-up in this rare clinical entity.