Cardiomegaly With an Absent Tricuspid Septal Leaflet: A Cadaveric Case Report.

The heart functions as a coordinated four-chambered pump, with four valves ensuring unidirectional blood flow. The tricuspid valve, located between the right atrium and right ventricle, consists of anterior, posterior, and septal leaflets that coapt during systole to prevent retrograde flow. Valvular disorders may result in stenosis or regurgitation, thereby increasing cardiac workload and predisposing to chamber dilation and heart failure. Congenital abnormalities, including partial or complete leaflet absence, are rare but can significantly disrupt normal hemodynamics. Reports of absent tricuspid valve leaflets are exceedingly uncommon and have primarily involved the anterior or posterior leaflet. During the thoracic dissection of a 41-year-old female body donor with a reported history of cardiovascular disease, cardiomegaly was identified. Gross examination revealed marked right atrial and ventricular enlargement. Internal inspection demonstrated a complete absence of the septal leaflet of the tricuspid valve, with intact anterior and posterior leaflets. Additional findings included dilation of the superior and inferior venae cavae, hypertrophied right atrial pectinate muscles, smooth and flattened right ventricular trabeculae carneae, and heterogeneous right ventricular myocardial thickness. The left heart structures were largely unremarkable aside from calcification of the mitral valve. Isolated absence of the septal tricuspid leaflet in adulthood has not been previously described. Loss of septal leaflet coaptation likely resulted in chronic tricuspid regurgitation, progressive right-sided volume overload, compensatory chamber dilation, and eventual cardiomegaly. Recognition of such rare structural variants is important for accurate imaging interpretation and surgical planning, particularly given potential distortion of critical landmarks such as the Triangle of Koch.