The Thick of It (2005)

S2E26 Deterioration of the Fight or Flight Response

Denny is in desperate need of a heart, and Izzie and George are frantic in their efforts to find one. Meanwhile, Derek holds a friend's fate in his hands as he performs surgery on Burke, who has been shot. With Denny's heart having stopped, Burke is unable to operate on him, leaving Denny in a critical state. Cristina takes charge of the ER, but her concern for Burke weighs heavily on her.