The HELICOPTER-1 Trial is a single centre, randomized trial evaluating the feasibility of administration of Heliox for prevention of myocardial ischemia in patients undergoing cardiac surgery. Half of the study population will be randomly assigned to the receive cardioplegia enriched with a 70:30 (Helium:Oxygen) Heliox mixture, while the other half will be randomized to receive the current clinical standard of care (nitrogen and oxygen in cardioplegia).