What is angioplasty?
Angioplasty is in simple terms, the removal of a block in a blood vessel. Most familiar form of angioplasty is coronary angioplasty – removal of blocks in the blood vessels of the heart.
How is angioplasty done?
Angioplasty is done using small tubes with balloons attached at the tip known as ‘balloon catheters‘. These catheters are introduced through the blood vessels in the wrist (radial artery) or the groin (femoral artery) and moved under X-ray cine imaging (fluoroscopy) to reach the destination vessel. Before passing the balloon catheter, it is usual to pass another wider catheter known as ‘guide catheter‘ and a ‘guidewire‘ through it to cross the blocked segment. The balloon catheter is then threaded on the guidewire to push it across the block. Once the balloon is across the block, it is inflated using a syringe like mechanism (indeflator – inflation deflation device). The balloon is filled with dilute X-ray contrast (iodinated dye) prior to insertion so that it can be visualized by fluoroscopy. The inflating device has a pressure gauge attached to it so that the inflation pressure can be monitored. Undue pressure within the balloon has to be avoided to prevent damage and sometimes rupture of the blood vessel.
What is done to prevent recoil of the vessel after angioplasty?
The recoil of a blood vessel after angioplasty can be prevented by implanting metallic stents within the segment from which the block was removed by angioplasty. Stents are tiny spring like structures kept in folded position like a folded umbrella and expanded using a balloon while inside the blood vessel in the desired position. Stents are mounted on balloon catheters for introduction into the blood vessel and passed through the guide catheter over the guidewire which was positioned during angioplasty.
What are the broad types of stents used?
Stents could be bare metal stents (BMS) made of nitinol, cobalt-chromium, stainless steel or platinum based alloys. For better efficacy, they can be coated with special medications which prevent recurrence of blocks at the implantation sites due to cell overgrowth. These are known as medicated stents or drug eluting stents (DES).