The Impact of Transient Control Performance of Pulsatile Flow on Hemolysis and Coagulation in Ex Vivo Heart Perfusion.

Background: Ex vivo heart perfusion (EVHP) is a promising approach for preserving donor hearts in a near-physiological state. However, the perfusion pressure and flow require adjustment to meet the requirements of aerobic metabolism, which may cause hemolysis and coagulation, consequently impairing myocardial function. The aim of this study is to investigate the impact of transient control performance of pulsatile flow on hemolysis and coagulation in EVHP.

Methods: Fresh porcine blood was circulated for 4 h in a mock loop equipped with a pulsatile pump and a self-designed compliant chamber, operating under conditions of a mean flow rate of 1 L/min and a mean pressure of 75 mmHg. Two typical proportional-integral-derivative (PID) control responses (underdamped response and overdamped response) were implemented to compare the impact of transient performance on hemolysis and coagulation. Blood samples were collected from the in vitro loop and analyzed for plasma free hemoglobin (PfHb), thrombin-antithrombin complex (TAT) and P-selectin levels.

Results: The experimental results demonstrated that the transient control performance of pulsatile flow had a significant impact on hemolysis and coagulation as circulation time increased. Compared to the overdamped response, the underdamped response resulted in more hemolysis and a higher risk of thrombosis. However, both the overdamped response and the underdamped response exhibited comparable levels of platelet activation.

Conclusion: During the control process of EVHP, frequent adjustments of perfusion pressure and flow should be minimized. Additionally, oscillations and overshoots in transient responses should be avoided to reduce hemolysis and thrombosis.