Surgical Management of a Rare Ascending Aortic Mural Thrombus Using a Modified Brain Isolation Strategy: A Case Report

INTRODUCTION: Ascending aortic mural thrombus (AMT) is an exceptionally rare condition. Diagnosis is often difficult because non-ECG-gated contrast-enhanced CT is susceptible to motion artifacts, and the distal ascending aorta can sometimes be challenging to evaluate using transesophageal echocardiography. A standardized surgical strategy for ascending AMT has not been established. CASE PRESENTATION: A 61-year-old man presented with transient left hemiplegia caused by embolic stroke. A non-ECG-gated contrast-enhanced CT scan revealed a thrombus-like structure in the ascending aorta; however, ECG-gated contrast-enhanced CT clearly demonstrated a thin-stalked and mobile thrombus, prompting urgent surgery. Cardiopulmonary bypass (CPB) was established using bilateral axillary artery cannulation and bicaval venous drainage. To minimize the risk of cerebral embolization during CPB initiation, the left common carotid artery (LCCA) was temporarily clamped under near-infrared spectroscopy monitoring. After cooling to 26°C, circulatory arrest with brachiocephalic artery and LCCA clamping and unilateral selective cerebral perfusion (uSCP) was performed. A highly mobile thrombus-like mass located just proximal to the brachiocephalic artery was excised with an adequate margin, followed by partial arch replacement with reconstruction of two arch branches. The postoperative course was uneventful, and pathology confirmed atherosclerosis with fresh thrombi and early organization. CONCLUSIONS: ECG-gated contrast enhanced CT is essential for accurate diagnosis of ascending AMT, particularly when small lesions mimic motion artifacts. The combination of bilateral axillary cannulation, LCCA occlusion, and a modified brain isolation strategy using uSCP may provide a safe and effective approach for surgical treatment of ascending AMT without neurological complications.