Endothelial glycocalyx during early reperfusion in patients undergoing cardiac surgery

Abstract

Background: Experimental cardiac ischemia-reperfusion injury causes degradation of the glycocalyx and coronary washout of its components syndecan-1 and heparan sulfate. Systemic elevation of syndecan-1 and heparan sulfate is well described in cardiac surgery. Still, the events during immediate reperfusion after aortic declamping are unknown both in the systemic and in the coronary circulation.

Methods: In thirty patients undergoing aortic valve replacement, arterial concentrations of syndecan-1 and heparan sulfate were measured immediately before and at one, five and ten minutes after aortic declamping (reperfusion). Parallel blood samples were drawn from the coronary sinus to calculate trans-coronary gradients (coronary sinus-artery).

Results: Compared with immediately before aortic declamping, arterial syndecan-1 increased by 18% [253.8 (151.6-372.0) ng/ml vs. 299.1 (172.0-713.7) ng/ml, p < 0.001] but arterial heparan sulfate decreased by 14% [148.1 (135.7-161.7) ng/ml vs. 128.0 (119.0-138.2) ng/ml, p < 0.001] at one minute after aortic declamping. There was no coronary washout of syndecan-1 or heparan sulfate during reperfusion. On the contrary, trans-coronary sequestration of syndecan-1 occurred at five [-12.96 ng/ml (-36.38-5.15), p = 0.007] and at ten minutes [-12.37 ng/ml (-31.80-6.62), p = 0.049] after reperfusion.

Conclusions: Aortic declamping resulted in extracardiac syndecan-1 release and extracardiac heparan sulfate sequestration. Syndecan-1 was sequestered in the coronary circulation during early reperfusion. Glycocalyx has been shown to degrade during cardiac surgery. Besides degradation, glycocalyx has propensity for regeneration. The present results of syndecan-1 and heparan sulfate sequestration may reflect endogenous restoration of the damaged glycocalyx in open heart surgery.

Fig 1. Systemic arterial concentrations of heart-type fatty-acid binding protein, syndecan-1 and heparan sulfate immediately before and at one minute after aortic declamping.

Individual values of heart-type fatty-acid binding protein, syndecan-1 and heparan sulfate concentrations in arterial blood immediately before (Before) and at one minute after (1 min after) aortic declapmping. ^#p < 0.05, ^##p < 0.001 for Wilcoxon signed rank test (immediately before aortic declamping vs. one minute after aortic declamping).

Fig 2. Trans-coronary concentration gradients of heart-type fatty-acid binding protein, syndecan-1 and heparan sulfate during early reperfusion.

The median and interquartile range values of trans-coronary concentration gradients of heart-type fatty-acid binding protein, syndecan-1 and heparan sulfate. T2—immediately before aortic cross clamping (i.e. immediately before ischaemia); T4—one minute after aortic declamping; T5—five minutes after aortic declamping; T6—ten minutes after aortic declamping. ^##p < 0.001 and ^#p < 0.05 [Wilcoxon signed rank test (coronary effluent blood vs arterial blood)].