Markers for endothelial activation during open heart surgery

Reliable markers for endothelial activation are needed when studying biocompatibility of cardiopulmonary bypass.

Blood samples from 21 patients undergoing combined valve and coronary artery bypass surgery were collected before anesthesia (T1), after re-transfusion of blood from the heart-lung machine (T2), and on the first postoperative morning (T3). Concentrations of soluble markers were determined using sandwich enzyme-linked immunoadsorbent assay for sICAM-1, sVCAM-1, and sE-selectin. The sera were also used to stimulate human umbilical vein endothelial cells (HUVEC) in culture for 6 hours, in which activation was measured using cell enzyme immunoassay for mICAM-1 and mVCAM-1.

The concentrations of sICAM-1 and sVCAM-1 increased during both measurement intervals (p < 0.05). The sICAM-1 T1 was 311.0 ng/mL (range, 271.0 to 350.7 ng/mL); the sICAM-1 T2 was 341.6 ng/mL (range, 322.0 to 422.0 ng/mL), and the sICAM-1 T3 was 400.2 ng/mL (range, 348.0 to 556.4 ng/mL; the sVCAM-1 T1 was 607.5 ng/mL (range, 497.8 to 813.8 ng/mL), the sVCAM-1 T2 was 755.3 ng/mL (range, 660.6 to 834.4 ng/mL), and the sVCAM-1 T3 was 1149.0 ng/mL (946.0 to 1406.0 ng/mL); whereas the sE-selectin increased from T1 to T3 (p < 0.01). Both the mICAM-1 (p < 0.002) and the mVCAM-1 (p < 0.005) increased on the human umbilical vein endothelial cells in culture after stimulation with the patient sera. The amounts of soluble markers in vivo were not correlated with the degree of endothelial activation in vitro, but were correlated with various operative variables including age, medication, and time of aortic cross-clamping.

Endothelial cells were activated during cardiopulmonary bypass. The soluble adhesion molecules sICAM-1, sVCAM-1, and sE-selectin displayed different kinetics, rendering it difficult to determine a simple expression for the degree of endothelial cell activation. Clinically, sVCAM-1 seemed to be the best-suited marker for endothelial cell activation, because it was only associated with aortic cross-clamping and heparin and protamine doses, and it also showed the largest numerical changes.