In the episode, Izzie's fiancé Denny, who also happens to be a patient, dies after receiving a heart transplant. To prepare for this emotional scene, Katherine says she sat alone on the set, listening to sad songs on her iPod.
Katherine also drew from personal experiences to make this moment as honest as possible. When Katherine was a child, she lost her brother in a tragic accident. She says she talked to her mother before the scene to get a sense of what it's like to lose a loved one.
"Pain is pain," Katherine says. "I wanted people who had had that kind of experience or who had lost someone suddenly that they loved to know that there are people who have felt this...there are people who are out there that you can identify with."
In real life, Katherine's love life isn't nearly as tragic. In fact, she's also engaged to be married to her boyfriend, musician Josh Kelley!