Pulmonary Valve Endocarditis With Mycotic Pulmonary Aneurysm Revealing a Previously Undiagnosed Perimembranous Ventricular Septal Defect in an Adult.

Infective endocarditis (IE) is a severe infection affecting the endocardial surfaces, including the heart valves and chordae tendineae. Ventricular septal defect (VSD), a common congenital heart defect, is associated with an elevated risk of developing IE. Pulmonary valve infective endocarditis (PVIE) is rare, especially in patients without typical risk factors, and is associated with high morbidity and mortality if not diagnosed and treated promptly. We present here a rare case of PVIE complicated by a pulmonary artery aneurysm, which led to the incidental discovery of a perimembranous VSD in a 33-year-old man. Transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) revealed the VSD with pulmonary valve (PV) vegetations, while CT imaging identified a mycotic aneurysm and splenic infarction. Blood cultures confirmed Streptococcus pharyngis as the causative pathogen. The patient received intravenous antibiotics, resulting in significant clinical improvement, with the resolution of fever and the normalization of laboratory parameters. This case underscores the importance of the early diagnosis and management of PVIE, as well as the need to consider underlying congenital heart defects.