Postoperative prosthetic mitral valve occlusion due to left atrial thrombus during veno-arterial extracorporeal membrane oxygenation: a case report

Background: Anticoagulation using heparin is generally used to prevent thrombus formation during mechanical circulatory support, such as veno-arterial extracorporeal membrane oxygenation (VA-ECMO). However, during the early period following cardiac surgery, anticoagulation becomes more difficult due to the greater risk of critical bleeding complications. Case presentation: A 71-year-old man presented with acute prosthetic valve occlusion caused by left atrial thrombus formation and bioprosthetic valve thrombosis during peripheral VA-ECMO following mitral valve replacement (MVR) despite continuous heparin administration and loading of antiplatelet agents. The VA-ECMO flow rate decreased 10 h after the intensive care unit (ICU) admission after MVR. Exploratory transesophageal echocardiography (TEE) examination revealed a left atrial thrombus, prosthetic valve obstruction by the thrombus, and an intrapericardial hematoma. Conclusions: Intracardiac thrombus formation might occur during VA-ECMO despite appropriate anticoagulation and loading of antiplatelet agents. Exploratory TEE examination was helpful in the detection of intra-atrial thrombus formation after cardiac surgery and surgical decision-making.