As a cardiologist in Los Angeles during the 1960s, Dr. Walter S. Graf became alarmed by the number of heart attack sufferers who died while en route to hospitals.

Inspired by an Irish physician who sent hospital doctors and nurses out into Belfast to treat cardiac patients, Graf in 1969 converted a white Chevy van into a "mobile critical care unit." He went on to outfit ambulances with defibrillators and technicians who knew how to use them, becoming one of a handful of doctors who created the modern paramedic emergency system.

Graf died Oct. 18 while under home hospice care in Los Angeles, according to Dr. Baxter Larmon, a professor at the David Geffen School of Medicine at University of California, Los Angeles. He was 98.

"He was a pioneer," said Larmon, who knew Graf for 40 years and delivered a eulogy at a memorial last week. "Today ambulances do trauma care, they do respiratory care, they provide all kinds of care. And it's all based on Graf's original model."

A procession of ambulances and fire trucks were driven to Graf's memorial, which was attended by 100 firefighters, Larmon said Thursday.

Graf was chief of staff for Daniel Freeman Hospital when he founded his pioneering paramedic training program. It was later expanded to include firefighters and emergency medical technicians, who Graf found performed just as well as nurses at treating cardiac patients. In 1999, the hospital merged with the UCLA Center for Prehospital Care.

"It's easy to take for granted the incredibly elaborate, sophisticated EMS system that we have today, but just 50 years ago, it did not exist," Dr. Clayton Kazan, the medical director for the Los Angeles County Fire Department, said in a statement. "While ambulance transportation existed, virtually no medical care was provided until the patient arrived at the hospital."

Graf's so-called "Heart Car" helped jump start "a movement that has been responsible for saving innumerable lives worldwide," Kazan said.

In 2010, Graf and three other physicians were honored by the County of Los Angeles Fire Museum as "pioneers in paramedicine." The others were J. Michael Criley, Eugene Nagel and Leonard Cobb.

Graf was born in New York City and received his medical degree from UC San Francisco in 1942. During World War II, he served as an Army physician in Europe and North Africa.

Graf's survivors include his wife, Joan; nine children and stepchildren; 19 grandchildren; and 22 great-grandchildren, Larmon said. He had three previous marriages.