Heart transplantation is the gold standard treatment for advanced heart failure, a major cause of premature death. The critical organ shortage however limits this therapeutic approach with a ratio of two recipient candidates for one allograft nowadays. The allocation of a growing number of marginal grafts increases the risk of primary graft failure and early death after transplant. All the most, conventional static cold storage allows for only 4 hours of ischemia. This time limitation induces a geographic restriction between donor and recipient. Ex vivo heart perfusion (EVHP) has been applied to expand the duration of organ preservation. This method provides continuous perfusion of the donor heart using oxygenated blood at 34°C. However no clearance of deleterious molecules for the heart (e.g. pro-inflammatory cytokines, oxygen radicals) is provided by commercially available machines for EVHP. Prolonged EVHP is therefore limited to a maximum duration of 10 hours. There is therefore a need for a portable blood filter connected to EVHP platform. Since there is no commercially available approach to achieve our clinical need, we aim at developing an optimal blood filtration device to ensure the homeostasis of the perfusate during prolonged EVHP. Our study aims to apply microfluidic technology for blood filtration during EVHP. We trust this approach would rapidly increase the chance for heart transplantation: 1) By increasing the duration for organ preservation, we could remove geographic restrictions for organ allocation; 2) By applying cardiovascular imaging using contrast agents, we could diagnose coronary artery disease in cardiac allografts from high-risk donors (age>55 years, cardiovascular risk factors); 3) By improving the quality of organ preservation, we could apply pharmacological intervention for organ repair and rehabilitation of marginal grafts before transplantation.