Abstract A 59-year-old male with severe biventricular heart failure presented with worsening dyspnea and angina. Following left ventricular assist device insertion, an Amplatzer Septal Occluder (ASO) was required as the patient's patent foramen ovale reopened. Seven months later, the patient underwent heart transplantation. The excised ASO was covered with a thick layer of host tissue on both right and left atrial sides, and organized thrombus was found between the metal wires. The foreign materials, the Nitinol wire and the synthetic (Dacron) fabric, showed a reactive infiltrate of macrophages, multinucleate giant cells, and scattered mononuclear cells.