In 1939, he developed the first practical ballistocardiograph, an instrument used to measure cardiac output. The device enabled Dr. Starr to diagnose and treat heart abnormalities in patients earlier and more accurately than previous methods allowed.
"Dr. Starr was truly one of the great figures in American medicine," Edward J. Stemmler, dean emeritus of Penn's School of Medicine, said yesterday. "He was more than a Philadelphian. He was an international figure."
A quiet, unassuming man devoted to his work, Dr. Starr continued his research into his 90s.
"Up until a year and a half ago, he came to his office every day," Stemmler said. "I used to think he produced more science after his retirement than most investigators do during their active careers. He was a remarkable gentleman, a man of unflagging interest and curiosity."
Dr. Starr chose medicine and the study of the heart as his life's work in part because his mother, Mary Barclay Starr, had been a victim of heart disease, said his son Harold.
Active and outgoing in her youth, Mary Starr became a near-invalid as an adult. "He always felt that his mother had been badly treated by her doctor," his son recalled.
A 1912 graduate of Chestnut Hill Academy, Dr. Starr went on to graduate
from Princeton University in 1916 and Penn's medical school in 1920.
After an internship at Massachusetts General Hospital, he returned to Penn as an instructor in pharmacology at the invitation of famed chemist Alfred Newton Richards.
In 1933, he was appointed the first Hartzell Professor of Research Therapeutics. He occupied the chair until his retirement in 1961, except for three years after World War II when he served as dean of the School of Medicine.
During the 1930s, Dr. Starr's research contributed to significant advances in the study of the heart and heart disease. He became internationally known for the development of the ballistocardiograph.
"He contributed greatly to the understanding of the heart as a pump and its operation," Stemmler said. "His use of physics and mathematics to measure the efficiency of the heart was a dramatic innovation at the time. With the ballistocardiograph, he could detect abnormalities much earlier. It opened up a whole new avenue of research."
In recognition of his achievements, Dr. Starr was honored with the Albert Lasker Award of the American Heart Association in 1957, the Kober Medal of the Association of American Physicians in 1967 and the Burger Medal of the Free University of Amsterdam in 1977. The University of Pennsylvania held a three- day symposium in his honor in 1977. In 1983, the university awarded him an honorary doctor of science degree.
Although his work occupied a great deal of his time, Dr. Starr took pleasure in, among other things, classical music and fly fishing.
"He felt, as I do, that one of the great natural treats of this world is to be on a trout stream by oneself," Stemmler said.
A fan of Bach, Dr. Starr for years spent his Sundays at the home of Henry Drinker, another prominent Philadelphia physician, where those in attendance would sing Bach's chorales, Starr said.
"He was a delightful man of great wit who was admired by his peers and students," Stemmler said.
Dr. Starr is survived by his sons, Harold and Isaac Jr.; daughters, Vidal S. Clay and Lynford Lardner; 12 grandchildren, and 11 great-grandchildren.
A memorial service will be held at 11 a.m. July 8 at St. Paul's Church, 22 E. Chestnut Hill Ave.
Gifts in Dr. Starr's memory may be made to St. Paul's Church.