Undetected intracardiac thrombus and subsequent embolism following cardiopulmonary bypass: a case report

Heparin is commonly administered to prevent thrombosis during cardiopulmonary bypass (CPB). However, the development of intracardiac thrombi under CPB has still been reported. 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. After aortic declamping, the arterial waveform in the right radial arterial line disappeared abruptly, and emergent thrombectomy was performed for thrombotic occlusion of the right radial artery. On the following day in the intensive care unit, the patient developed acute left-sided paralysis without any documented episode of atrial fibrillation. Computed tomography confirmed occlusion of the right internal carotid artery, prompting a second emergent thrombectomy. 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 transesophageal echocardiography (TEE) is the gold standard for detecting intracardiac thrombi, it can yield false negatives. 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.