As suggested by the novel’s title, heartbeats are a significant recurring motif in Annie’s narration. The book opens with a heartbeat rhythm: “thump-thump, thump-thump” (9) that is used as onomatopoeia for the sound of running feet. This rhythm is a repeated refrain throughout the book, used when Annie runs. An important moment in Annie’s understanding of a new life growing inside her mother occurs when she hears the fetus’ heartbeat, which makes a “a-woosh a-woosh a-woosh” sound (75). It is this sound that prompts Annie to imagine herself, her parents, her grandfather, and the baby as a team. When Annie’s grandfather and the newborn baby fall asleep, Annie checks both of their heartbeats to make sure that they are still alive, indicating her anxiety and need to protect them both. The central theme of the rhythms and cycles of life is represented by the beating of a heart, a highly recognizable symbol of life itself.

Annie’s assignment to draw apples becomes a way of measuring the passage of time in the story, along with her mother’s pregnancy. Just as the novel begins with the family preparing for a baby and ends with its arrival, Heartbeat is similarly bookended by the introduction and completion of the apple drawings.