Final answer:
The method used to introduce a catheter into a blood vessel for treatment purposes is called angioplasty, which involves inflating a balloon to widen the vessel and often includes inserting a stent to keep it open.
Step-by-step explanation:
The method used to introduce a catheter and guide wire into a blood vessel safely is known as angioplasty. During this procedure, a specialized catheter with an expandable balloon tip is carefully inserted through the skin into a superficial blood vessel, usually in the leg. It is then navigated to the site of occlusion within the bloodstream. Once positioned correctly, the balloon on the catheter is inflated, compressing the plaque against the vessel wall, which widens the vessel to increase blood flow. After deflation, the balloon and catheter are retracted. Often, a stent is inserted to keep the vessel open and prevent it from collapsing.