Heart conditions kill 3 out of 10 people every year. Heart attacks and failures, hypertension, strokes… However, you may not be aware that the space industry has given Humanity a kind of patch for it all: heart valves.
It may sound like science fiction, but this contraption was designed for spaceship engines and ended up within the chest of human beings. Their mission was originally to channel the fuel and to calibrate how much of it gets into the engine, and how fast. Just as the heart keeps the blood flowing around the body (although blood flows at a constant rate).
Sometimes a valve is enough, but often it just provides extra time while a live organ arrives to be transplanted.