A Large Tricuspid Subvalvular Apparatus Infective Endocarditis Undetected by Transthoracic Echocardiography

A 39-year-old male with a history of intravenous drug use (IVDU) and no significant cardiovascular disease was admitted to the ICU for management of septic shock and acute hypoxic respiratory failure secondary to septic pulmonary emboli. Due to a high clinical suspicion for right-sided infective endocarditis (IE), he received a transthoracic echocardiogram (TTE), which did not reveal any vegetations. However, a transesophageal echocardiogram (TEE) was subsequently performed; this showed a large 2.4 cm vegetation in the septal aspect of the tricuspid valve (TV) subvalvular apparatus. He urgently underwent surgical removal of the vegetation and repair of the TV. Postoperatively, he clinically recovered with appropriate antibiotic therapy. TEE is the ideal imaging modality in evaluation for IE, but a minimally invasive TTE is often performed first. This case highlights a highly unusual anatomic location of IE, which harbored a large vegetation undetected by TTE. In patients without cardiac devices or non-native valves, an urgent TEE remains diagnostically essential if there is a high clinical suspicion for right-sided IE, even if a TTE shows no evidence of IE.