The Harvesters (2000)

Danielle Carver has inherited the same heart disease her mother died of at her birth and is in dire need for a donor heart. Luckily the organ is quickly available and Danielle undergoes surgery. One year later Danielle is completely restored and she and her father Jeff decide to visit Rachel Pearce, the mother of the boy who donated the heart, to thank her. But Rachel knows nothing of the donation. Rachel and Jeff decide to find out more about this weird case, but they dig too deep...