Endothelial dysfunction in the early postoperative period after major colon cancer surgery

<span class="paragraphSection"><strong>Background.</strong> Evidence suggests that endothelial dysfunction in the early postoperative period promotes myocardial injury after non-cardiac surgery. The aim of this study was to investigate the impact of colon cancer surgery on endothelial function and the association with the l-arginine-nitric oxide pathway postoperatively.<strong>Methods.</strong> Patients undergoing elective colon cancer surgery (n = 31) were included in this prospective observational cohort study. Endothelial function, as measured using the reactive hyperaemia index (RHI), was assessed non-invasively using digital pulse tonometry. RHI and plasma concentrations of L-arginine, asymmetric dimethylarginine (ADMA), dihydrobiopterin and biopterin metabolites, tetrahydrobiopterin (BH4) and total biopterin were measured before surgery, at four h after surgery and at postoperative day one and two. Cardiac troponin I was measured before surgery and once daily on postoperative days one to four.<strong>Results.</strong> Preoperative RHI was 1.86 (1.64 – 2.11) and decreased significantly during the observation period (linear mixed effects model of serial measurements, <span style="font-style:italic;">P = </span>0.015). Both L-arginine (<span style="font-style:italic;">P</span> < 0.001) and ADMA (<span style="font-style:italic;">P = </span>0.024) decreased during the postoperative period. All biopterin metabolites were significantly decreased after surgery. A significant positive correlation was found between logAUC(l-arginine/ADMA) and logAUC(RHI) (<span style="font-style:italic;">P = </span>0.015) and between logAUC(L-arginine/ADMA) and logAUC(BH4) (<span style="font-style:italic;">P = </span>0.015). None of the patients had cardiac troponin I elevations.<strong>Conclusions.</strong> RHI was attenuated in the first days after colon cancer surgery indicating acute endothelial dysfunction. Endothelial dysfunction correlated with disturbances in the L-arginine – nitric oxide pathway. Our findings provide a rationale for investigating the hypothesized association between acute endothelial dysfunction and cardiovascular complications after non-cardiac surgery.<strong>Clinical trial registration.</strong> NCT02344771.</span>

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