Acute histopathological and biochemical changes in saphenous vein grafts during coronary artery bypass grafting: A closer look at mTOR signaling.

Background: This study aims to investigate whether acute surgical manipulation of great saphenous vein grafts during coronary artery bypass grafting alters mammalian target of rapamycin (mTOR) activation and induces early histopathological damage. Methods: Between September 2022 and September 2023, a total of 44 elective coronary artery bypass grafting patients (38 males, 6 females; mean age: 60.8±8.3 years; range, 36 to 70 years) were included in this prospective study. Saphenous vein segments were collected pre- and post-preparation. Light microscopy and enzyme-linked immunosorbent assay were used to assess structural changes and mTOR levels. Results: Histopathological analyses revealed endothelial disruption and subendothelial inflammatory infiltration in post-preparation samples. However, mTOR protein levels showed no significant difference between pre- and post-manipulation tissues (p=0.41). Conclusion: Mechanical stress during great saphenous vein graft preparation causes notable endothelial injury, but does not acutely activate the mTOR pathway. These findings suggest that mTOR may not participate in early responses, but could be implicated in long-term vascular remodeling.