Supernatural: 1x12

Faith

While battling a demon, Dean is electrocuted, resulting in permanent damage to his heart and leaving him with only a couple of months to live. A despondent Sam searches desperately for a way to save his brother and believes he may have found an answer through a preacher who claims to heal the incurable. However, Dean and Sam discover that the preacher is getting help from the Grim Reaper who is trading one life for another he feels is less worthy.