Background

Deep hypothermic circulatory arrest (DHCA) is widely used in proximal thoracic aortic surgery; however, its association with subclinical cerebral ischemic changes remains poorly understood. Diffusion-weighted magnetic resonance imaging (DW-MRI) enables sensitive detection of silent cerebral infarction (SCI), which may occur in the absence of overt neurological deficits.

Methods

This prospective observational study included 35 consecutive adult patients undergoing proximal thoracic aortic surgery under DHCA at 18 °C without selective cerebral perfusion. Preoperative and postoperative DW-MRI scans were obtained in all patients. Silent cerebral infarction (SCI) was defined as the presence of at least one new ischemic lesion on postoperative DW-MRI not present preoperatively. Perioperative neuron-specific enolase (NSE) levels and intraoperative near-infrared spectroscopy (NIRS) measurements were recorded. Factors associated with SCI were explored using univariable and multivariable logistic regression analysis.

Results

Postoperative silent cerebral infarction was detected in 19 patients (54.3%), whereas no ischemic lesions were observed on preoperative DW-MRI.

In univariable analysis, increasing age (OR 1.06, 95% CI 1.01–1.13; p = 0.021), Cardiopulmonary bypass time (CPB time) (OR 1.01, 95% CI 1.00–1.03; p = 0.024), and aortic cross-clamp time (CC time) (OR 1.04, 95% CI 1.01–1.07; p = 0.006) were associated with SCI. In age-adjusted multivariable models constructed separately for operative time variables, CC time remained independently associated with SCI (OR 1.03, 95% CI 1.01–1.06; p = 0.015), whereas CPB time did not retain statistical significance (OR 1.02, 95% CI 0.99–1.03; p = 0.089). Additional collinearity assessment showed a strong correlation between CPB time and CC time, and sensitivity analyses supported the persistence of the association between CC time and SCI. DHCA time, NIRS parameters, and NSE changes were not significantly associated with SCI. Although postoperative NSE levels increased compared with preoperative values, the change in NSE did not predict the occurrence of SCI.

Conclusions

Silent cerebral infarction was frequently detected on postoperative DW-MRI following proximal thoracic aortic surgery performed under DHCA. Aortic cross-clamp time was associated with SCI development; however, this association should be interpreted cautiously, as it may reflect procedural complexity, cumulative aortic manipulation, and embolic burden rather than the isolated effect of circulatory arrest time.