When the Heart Interferes with the Brain: Effects of Cardiac Surgery on Higher Cognitive Functions

Objective: This study aims to investigate the patterns of disrupted structural connectivity in brain lesions following complex cardiac surgery, assess their localization relative to major functional brain networks, and explore potential mechanisms underlying postoperative cognitive and neurological dysfunction. Materials: A systematic literature review identified 20 adult patients with brain lesions following cardiac surgery from 19 studies. Inclusion criteria required MRI or CT imaging suitable for lesion mapping. Imaging data were manually traced onto the MNI152 standard brain space. Two control datasets were used: a resting-state fMRI database of 110 healthy subjects and the ATLAS stroke lesion dataset with 304 ischemic lesions. Methods: Lesions were manually delineated using FSLeyes and mapped to MNI152 space. Lesions were compared with control stroke lesions matched by hemispheric lateralization. Statistical analyses, including non-parametric permutation testing (5,000 permutations), were performed with the Randomise tool. Disconnection patterns were estimated with the Disconnectome tool, and lesion volume was included in regression models. Results: The median age of the 20 patients was 59.2 years. Surgeries included coronary artery bypass grafting (n=10), valve surgery (n=4), repair of type-A aortic dissection (n=2), atrial myxoma resection (n=1), and multiple procedures (n=3). Neuroimaging included 12 MRI and 8 CT scans, all showing ischemic lesions. No neuropsychological data were reported. Lesion analysis showed no significant results; however, functional connectivity analysis revealed significant disconnection patterns. Post-surgery lesions were associated with increased disconnection in the occipital lobe, pulvinar, and medial frontal regions. Lesion volume did not significantly affect outcomes. Discussion: Our analysis revealed consistent functional disconnection patterns, primarily in the occipital lobe, pulvinar, and medial frontal cortex, in patients with ischemic lesions after cardiac surgery. While no direct correlation was found between lesion location and cognitive symptoms, the disruption of these regions suggests vulnerability in networks related to attention, visuospatial processing, executive functions, and emotional regulation. These findings support the hypothesis that postoperative cognitive dysfunction (POCD) is due to network disconnection rather than focal damage. Functional connectivity analysis is critical for detecting these alterations, emphasizing the need for integrating structural and functional imaging in understanding cognitive outcomes. Conclusion: Cardiac surgery may disrupt functional connectivity in regions essential for higher-order cognitive functions, including the occipital lobe, pulvinar, and medial frontal cortex. These disruptions likely contribute to postoperative cognitive deficits, such as attention, memory, and behavioral changes. Identifying at-risk areas may guide targeted rehabilitation strategies and early interventions to improve patient outcomes.