Undetected Intracardiac Thrombus and Subsequent Embolism Following Cardiopulmonary Bypass: a case report

Background: Heparin is commonly administered to prevent thrombosis during cardiopulmonary bypass (CPB). However, the development of intracardiac thrombi under CPB has still been reported. Case Summary: A 79-year-old man with three-vessel coronary artery disease and a history of bladder cancer underwent on-pump coronary artery bypass grafting. His cardiac function was compromised by a low ejection fraction and a left ventricular aneurysm. After aortic declamping, the arterial waveform in the right radial artery line suddenly disappeared. Emergency thrombectomy was performed, and a thrombus was confirmed. On the following day in the intensive care unit, the patient suddenly developed left-sided paralysis without any episode of atrial fibrillation. Computed tomography demonstrated occlusion of the right internal carotid artery, and an emergency thrombus removal was carried out. Discussion: Despite full heparinization, intracardiac thrombus formation can still occur during CPB due to patient- and surgery-related factors such as cancer, coronary artery disease, low ejection fraction, and cardiac arrest. While transesopageal echocardiography (TEE) is the gold standard for detecting intracardiac thrombi, it can yield false negatives. Conclusion This highlights the importance of thorough TEE screening just before aortic declamping in patients at high risk for intracardiac thrombus, and possibly the need for additional imaging modalities to improve thrombus detection.