It’s an endovascular procedure to widen narrowed or obstructed arteries to the veins, typically to treat arterial artherosclerosis. An empty, collapsed balloon, known as a balloon catheter, is passed over a wire into the narrowed locations and then inflated to affixed size.
The balloon forces expansion of the stenosis (narrowing) within the vessel and the surrounding muscular wall, opening up the blood vessel for improved flow, and the balloon is then deflated and withdrawn.
A stent may or not be inserted at the time for ensure the vessel remains open.