Background: Postoperative organ dysfunction in conventional surgery for abdominal aortic aneurysm (AAA) is associated with a complex inflammatory reaction, with activation of coagulation and fibrinolysis. A prospective,observational study was performed to define the complex plasma proteomic changes after AAA repair and to identify factor(s) that may affect myocardial function in uncomplicated procedures.
Methods: Ten patients undergoing infrarenal AAA repair were investigated. Eight subjects subjected to major abdominal surgery served as controls. Hemodynamic changes were continuously monitored by using the pressure recording analytical method technique. The time course of plasma proteins was investigated after induction of anesthesia and at different times after surgery (6 h, 12 h, 24 h, 36 h) by using two-dimensional difference gel electrophoresis, matrix-assisted laser desorption/ionization-time of flight mass spectrometry, and Western blot. The effects of plasma on the functional properties of isolated rat ventricular myocytes were also investigated.
Results: In AAA patients alone, 18 spots were found to change more than two-fold in expression level, spot identification revealing an increased thrombin generation 6 h after surgery. At the same time cardiac cycle efficiency significantly reduced versus baseline (-0.5 +/- 0.9 vs. 0.18 +/- 0.3 in AAA patients, P < 0.01; 0.4 +/- 0.1 vs. 0.2 +/- 0.3 in control surgery, not significant; P < 0.01 group x time interaction at ANOVA). Plasma obtained 6 h after AAA surgery dose-dependently inhibited contractile function of control rat myocytes (percent shortening fell by 51% with 10% of AAA plasma and was abolished with 20% of AAA plasma, P < 0.001 for both). The inhibitory response was abolished by thrombin antagonism.
Conclusions: These findings show for the first time the possible role of thrombin generation within the complex activation of inflammatory response in causing hemodynamic instability in the early postoperative period after AAA surgery.