From Wikipedia

Chernobyl Heart

Chernobyl Heart is a 2003 documentary film by Maryann DeLeo. The film won the Best Documentary Short Subject award at the 2004 Academy Awards.

In the film, DeLeo travels through Ukraine and Belarus with Adi Roche, the Irish founder of the Chernobyl Children's Project International, observing the effects of the Chernobyl nuclear disaster on the health of children in the area. In addition to mutations and severe radiation poisoning, many children suffer from a previously unknown cardiac degradation condition, so common in the area it is known as "Chernobyl heart. DeLeo herself contracted caesium poisoning during the making of the film, although she was successfully treated and made a full recovery.