The purpose of this study is to evaluate whether non-ischemic heart preservation (NIHP) of extended criteria donor hearts using the XVIVO Heart Preservation System (XHPS) is a safe and effective way to preserve and transport hearts for transplantation. Participants will be on the heart transplant waiting list. The XVIVO Heart Preservation System is an experimental device that keeps a donated heart preserved for longer periods than standard preservation before a transplant. It is used to keep donor hearts cold and oxygenated by pumping a solution through the heart to provide oxygen and nutrients. The study will only involve an available and matching donor heart that meets extended criteria. Extended criteria hearts come from donors where the heart may not meet the typical criteria for transplant. The typical criteria for hearts used for transplant are outside of the body usually no more than 4 hours and tend to be from younger donors with limited risk factors. Patients will retain the opportunity to accept a standard criteria donor heart outside of the study (i.e., remain on the waitlist). If an extended criteria donor heart becomes available and is matched, the patient may receive a transplant with a heart transported/preserved with the XVIVO Heart Preservation System (XHPS) if eligible for the study.