A stent is a corrugated metal tube used to open narrowed heart arteries to improve blood flow and reduce anginal (chest pain) symptoms.
You will undergo a coronary angiogram in the usual fashion usually through the wrist artery under local anaesthetic. A wire will be passed through the heart artery and narrowing, a balloon used to expand the artery which then allows a stent to be implanted and relieve the narrowing.
https://jshearthealth.ie/treatment/coronary-stent-insertion-pci/