The moment between one heartbeat and another, that's all the time she had left. In the end that's all the time any of them had left.

One heartbeat and her hands were slipping from the lever, falling, falling. The next beat came in another universe.

One heartbeat, the look on the face of a young woman who had a year of hell, saying goodbye. The next beat came from beyond the TARDIS door as she walked away without a glance back.

One heartbeat, she's begging, pleading for him not to, as his fingers press against her temples. The next beat and The Doctor Donna is no more.

One heartbeat, a sob is ripped from her chest "Raggedy Man, goodbye," The next beat matches up with her love's, who she gave everything to be with forevermore.

One heartbeat, she walks so slowly down a cobblestone road, "Let me be brave, let me be brave," and… One day we all must face The Raven.