He is taken prisoner by communist guerillas led by physically strong
Wong-Chu. Wong-Chu wants Stark to build him a powerful weapon, with the unwilling help of Chinese
Professor Yinsen, in return for a promise to have a surgeon remove the shrapnel. Instead they build an iron suit, with extensive use of transistors. The suit includes a pacemaker to keep Stark's heart going after the shrapnel reaches it.
The suit is ready just as Stark's heart is about to give out. Yinsen gives his life to buy time for the suit to power up.
The original suit is a clunky grey affair, controlled by Stark's brain. It has air-pressure boot jets, and various attachments such as suction cups and powerful transistor-powered magnets. And of course it is strong and bullet-proof.
Calling himself
Iron Man, Stark scatters the guerillas, blows up the base and Wong-Chu, and heads back to civilisation.
He already knows he won't be able to take the pacemaker breastplate off. In fact at this point he thinks he will have to keep the whole armour on forever.
Give that special marvelite a timely gift