CNN  —  Kyiv was burning as Dr. Borys Todurov sped through the city in an ambulance, undeterred by the deep thuds of explosions and the terrifying sounds of Russian drones flying overhead. He was determined to deliver his precious cargo: a human heart. Todurov’s patient – a child – was seriously ill in a hospital. He had hours to act. The child has been living with a heart disease for several years, but her condition deteriorated earlier this week and Todurov knew a new heart was her only