Orlando, Fla. ? A Kentucky boy who died after riding Walt Disney World’s Rock ‘n’ Roller Coaster had heart defects, a preliminary autopsy released Friday showed.

Dr. Sara H. Irrgang, associate medical examiner for Orange and Osceola counties, also found no evidence of injuries. Her findings do not necessarily mean that 12-year-old Michael Russell died because of congenital heart abnormalities. Irrgang will look further and issue a final report in a few weeks.

Disney safety officials, accompanied by a state ride inspector, examined the indoor coaster at Disney-MGM Studios Thursday night and concluded it was safe. The ride reopened at 8 a.m. Friday.

Michael, who was vacationing with his family from Fort Campbell, Ky., boarded the short ride with his mother, father and younger brother late Thursday morning but was found limp as the ride finished. His father, Byron Russell, an Army Green Beret, immediately began CPR. Paramedics who arrived six minutes later took over and shocked Michael with a defibrillator. But the boy never revived and was pronounced dead at Celebration Hospital.

Michael’s parents told Orange County deputies on Thursday that he had annual physicals and was in good physical health.

His death is the seventh in 18 months involving people stricken at Walt Disney World attractions. In at least four of the other cases, autopsies blamed cardiovascular problems, including the most recent, Hiltrud Blumel, a 49-year-old German woman who died after riding Mission: Space on April 11 at Epcot.

The Medical Examiner’s Office also released a final autopsy report Friday on Blumel’s death, saying she died of a stroke caused by high blood pressure.

Regarding Michael’s autopsy, the Medical Examiner’s Office offered no details about what sorts of abnormalities were discovered, how serious they could have been or whether they might have been difficult to detect in routine physicals. Congenital heart abnormalities involve structural problems with the heart that are present at birth.