Inferior Vena Cava–Left Atrial Connection Hidden Beneath Large Secundum Defect. A Case Report

Inferior vena cava (IVC) drainage into left atrium is an exceptionally rare congenital anomaly and may remain unrecognized when associated with a large atrial septal defect (ASD). A 35-year-old-man presented with progressive exertional dyspnea and fatigue. Transthoracic echocardiography, transesophageal echocardiography, and cardiac catheterization demonstrated a large secundum ASD with severe septal malalignment, while systemic venous drainage was interpreted as normal. During surgical ASD repair, an unexpected IVC-to-left atrium connection was identified and redirected to right atrium. Careful assessment of IVC inflow is essential in patients with large malaligned ASD despite normal oxygen saturation.