" She had never paid much attention to the heart beating in her own chest. As she watched the pattern traced by Korsak's, she became aware of her own pulse. She had always taken her heartbeat for granted, and she wondered what it would be like, to hang on every beat, fearful that the next might not come. That the throb of life in her chest would suddenly go still. "

― Tess Gerritsen , The Apprentice (Rizzoli & Isles, #2)