25-year-old student Thorsten Siess invented the Impella medical device for heart support.

25-year-old Thorsten Siess, a mechanical engineering student, invented a successful medical device to help keep hearts pumping blood during surgery or heart attacks. The device, called Impella, can be inserted without major surgery. Siess, who is now CTO at Abiomed (part of Johnson & Johnson), offers this advice to new grads: meet inspiring professors, write grants for your education, and don't be afraid to start a company.