Nursing home resident Mabel Taylor died of heart disease, but sudden exposure to cold and stress after she was locked outdoors contributed to her death, a forensic pathologist testified.

An autopsy on Mrs. Taylor showed a blood vessel in her heart was 75 percent blocked and another was 35 percent blocked, Dr. Shaun Ladham testified yesterday. The sudden onset of cold and stress after Mrs. Taylor was locked outside in a fenced nursing home courtyard caused a sudden arrhythmia in her diseased heart, he said.

Dr. Ladham, formerly of the Allegheny County coroner's office, said he did not believe Mrs. Taylor suffered the arrhythmia before she went outside. Her body temperature indicated she had been dead outdoors for at least two hours, he said.

His testimony came in the trial of former nursing home administrator Martha F. Bell, 60, of West Mifflin, and the facility she ran, Ronald Reagan Atrium I Nursing, Research and Rehabilitation Center in Robinson.

Mrs. Bell and Atrium are charged with neglect of a care-dependent person, involuntary manslaughter and reckless endangerment in the death of Mrs. Taylor, 88, on Oct. 26, 2001.