Heche, 53, also had a fractured sternum caused by “blunt trauma,” according to information on the website of the Los Angeles County Medical Examiner-Coroner.
A full autopsy report was still being completed, the coroner’s office said.
The Emmy-winning film and television actor was removed from life support Sunday at a burn center. She was injured when her car jumped a curb and smashed into a West Los Angeles home on Aug. 5. The car and the home burst into flames. Only Heche was injured.
Heche suffered a “severe anoxic brain injury” caused by a lack of oxygen, according to a statement released last week on behalf of her family and friends.
She was declared brain-dead but was kept on life support until her organs could be donated.
Detectives looking into the crash had said narcotics were found in a blood sample taken from Heche. However, police ended their investigation after she was declared brain-dead.
The coroner’s office listed Aug. 11 as her date of death.
Heche first came to prominence on the NBC soap opera “Another World” in the late 1980s before becoming one of the hottest stars in Hollywood in the late 1990s. She was a constant on magazine covers and in big-budget films opposite actors including Johnny Depp and Harrison Ford.