LEUKOCYTE ACTIVATION FOLLOWING BOVINE VAD IMPLANTATION

Abstract

Purpose: It is unclear how ventricular assist device (VAD) implantation and operation activates inflammatory pathways due to the chronic inflammation associated with advanced cardiomyopathy. The healthy bovine model allows examination of inflammatory effects due only to VAD placement and operation. We have thus measured circulating monocytes expressing tissue factor (MTF), monocyte-platelet aggregates (MPA), and granulocyte-platelet aggregates (GPA) in rotary VAD implanted calves. Methods: To characterize new flow cytometric assays, blood from 4 normal calves was activated with 3 μM PMA+5 mM A23187 (MTF) or 5 μM thrombin receptor agonist peptide (MPA, GPA). Unactivated blood served as control. Calves implanted with an axial flow VAD (n=6) or centrifugal flow VAD (n=8), had MTF, MPA and GPA measured preoperatively and twice weekly post-operatively. Results: In vitro activation produced significant increases in the leukocyte assays (Table). In vivo studies showed pre-operative calves had low levels of MTF, MPA, and GPA. Levels rose dramatically after surgery, peaking on post-operative day (POD) 1, then declined, but remained significantly elevated versus control.TableConclusions: Inflammation as evidenced by circulating activated leukocytes and leukocyte-platelet aggregates can be attributed to VAD implantation and operation in healthy bovines. This activation wanes in the post-operative period, but remains markedly elevated over pre-implant levels.