National award-winning South Indian actress Kalpana Ranjani died on Monday in Hyderabad, at the age of 51 years, due to a heart attack. Kalpana bagged the National Award in 2012 for the best-supporting actress for her role in the Malayalam movie 'Thanichala Njan'. In her lifetime, Kalpana acted in about 300 films and is best known for films like 'Kaliveedu'.