Every time your heart beats, an electrical current has been sent from certain cells to the rest of the heart muscle tissue, triggering your heart to contract and push blood through your body. When these signals go awry, major health issues such as heart attacks can occur. Enter the pacemaker, a small implanted device that keeps your heart beating. Did you know, implantable pacemakers were invented by accident? This volume explores the history, struggles, and the accidental invention of the pacemaker, a device that beats hundreds of thousands of times each year to save people’s lives.