Dr. Walter Graf died this October. He was 98. By the time of his death, he had helped save more lives than anyone can count. How did he do it? He used the Heart Car!

What would you do if you needed urgent medical help? You’d probably dial 9-1-1. Then what would come speeding your way? That’s easy: an ambulance! And what would be inside? Medical equipment and staff, right? These would help keep you alive on the way to the hospital.

But things weren’t like that before Mr. Graf came along. Before him, ambulances didn’t have medical equipment. No Emergency Medical Technicians (EMTs) or paramedics rode onboard. In fact, an ambulance ride worked more like hopping into a taxi. The ambulance took you to the hospital. But it didn’t do much else.

At first, Dr. Graf served as an Army physician in Europe and North Africa. Later, he became an important doctor in California. He took care of people with heart problems.

Dr. Graf noticed something. Because ambulances worked like taxis, people having heart attacks often died on the way to the hospital. What if they had the help of proper equipment and staff just a little sooner? Dr. Graf believed they could easily survive.

He was right. In 1969, he changed a white Chevy van into a “mobile critical care unit.” People called it the Heart Car. It had a nurse inside. It also had a defibrillator. You may have seen someone use a defibrillator in the movies—or maybe even in real life. Medical staff use them to restart a person’s heart. When a person is not breathing, they attach electrodes to his or her chest. Then they yell, “clear!” That means, “Everyone stand back!” Then they use electricity to shock the patient’s heart back into its regular rhythm.

Not everyone thought the Heart Car was a good idea at first. But it started something very big and very good: today’s Emergency Medical Services (EMS). EMS comes to rescue you when you need help. For that, we owe Mr. Graf a big “thank you!”