Cardiac surgery with valve replacement temporarily disrupts the hippocampal memory network.

Background: Systemic inflammation after heart valve replacement surgery commonly results in complications including cognitive impairment. This study was designed to investigate whether valvular heart disease itself and inflammation after valve replacement surgery affects cognition and the related functional connectivity (FC) of the hippocampal memory network.

Methods: Forty-three patients with valvular heart disease were screened for recruitment and assessed with cognition function tests, blood inflammatory cytokine measurements, and functional magnetic resonance imaging scans before surgery and on postoperative day 7 and 30. Age- and sex-matched healthy controls (n=30) were recruited for comparison. The brain FC networks using the hippocampus as a seed were analysed. Bivariate correlation and structural equation model analyses were carried out to investigate the association between altered FC, memory, and inflammation.

Results: Thirty-five patients and 29 healthy controls completed the study, and their data were finally analysed and reported. Compared with healthy controls, the surgery group had increased FC in the bilateral precuneus and middle cingulate and paracingulate gyri before surgery. They exhibited impaired memory, increased plasma concentrations of proinflammatory cytokines, and decreased hippocampal FC at postoperative day 7. At 30 days after surgery, the FC abnormalities seen before surgery and at postoperative day 7 were restored to the level comparable with the healthy controls. High systemic inflammation was significantly associated with worse memory and lower FC in the hippocampal memory network.

Conclusions: Valve replacement surgery temporarily disrupts the hippocampal memory network with transient associated memory decline.

Clinical trial registration: ChiCTR2300069614.