Among 20 coronary artery bypass grafting (CABG) patients, saphenous vein segments stored in autologous heparinized arterial blood (AHB) or histidine-tryptophan-ketoglutarate (HTK) solution preserved endothelial coverage at roughly 89% versus only 78% with standard normal saline (NS). Immunofluorescence confirmed all three hydrogen sulfide (H₂S)-synthesizing enzymes — CSE, CBS, and 3-MPST — are present in saphenous vein endothelium, with CSE the dominant isoform. NS caused marked depletion of these enzymes alongside significantly lower eNOS and CD31 expression, while AHB and HTK maintained substantially higher levels (p < 0.001).
This preprint, not yet peer-reviewed, addresses a clinically consequential but underappreciated variable: what surgeons soak vein grafts in during the minutes before implantation. Normal saline remains the default in many centers despite longstanding evidence of its hypertonicity-related endothelial toxicity. The H₂S angle is genuinely novel — prior CABG preservation research focused on nitric oxide signaling and mechanical distension injury rather than gasotransmitter enzyme preservation. CSE-derived H₂S has well-documented vasodilatory, anti-inflammatory, and anti-apoptotic roles in vascular biology, making its depletion mechanistically plausible as a contributor to early graft failure. Limitations are notable: the sample is small (n=20), the model is ex vivo with short exposure windows, and long-term patency outcomes were not tracked. Whether enzymatic preservation translates into measurable graft survival differences in clinical follow-up remains unproven. Still, the finding is directionally important — surgeons using NS by habit may be inadvertently sabotaging graft endothelium before the operation even concludes.
