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Coronary Stents: A Basic Guide to Angioplasty

What is a stent?

A coronary artery stent is a metallic mesh tube that expands inside the coronary artery. A stent is inserted during or immediately after the angioplasty procedure. Angioplasty is a procedure to open a narrowed and blocked blood vessel, (the blood vessel that provides blood to the heart).

A stent prevents the artery from closing up again and treats the blocked or narrowed coronary artery. A Drug-Eluting Stent (DES) has a drug inserted in the stent, which gets released slowly and prevents the artery from closing in the long run1. The device is designed in such a way to keep the artery open, support the wall of the artery, and improve the flow of blood and oxygen in the blood vessel2.

Types of coronary stents

  1. Bare metal stents (BMS)4The development of bare-metal stents (BMS) was a major advance relative to balloon angioplasty in managing symptomatic coronary artery disease and prevents restenosis. E.g. Stainless steel, Cobalt-chromium alloy, Platinum chromium alloy.
  2. Drug-eluting stents (DES)4Drug-eluting stents (DES) have an antiproliferative drug and a polymer which serves as a vehicle for the drug and controls the drug release rate. The drug inhibits excessive growth of neointima, a major cause of restenosis. Since each DES is unique, differences may be observed concerning deliverability (ease of placement), efficacy (prevention of restenosis), and safety (rates of stent thrombosis). First-generation DES includes sirolimus-eluting stents (SES; 2003) and paclitaxel-eluting stents (PES; 2004), Second-generation DES, including zotarolimus- and everolimus-eluting stents
  3. Bioresorbable scaffold system (BRS)5Bioresorbable scaffolds (BRS) were developed as an alternative to drug-eluting stents (DES) to facilitate vessel restoration and reduce future adverse events. However, problems regarding the safety and effectiveness of first-generation BRS have restricted their clinical use. The newer type of stents, called bioresorbable scaffolds provides a temporary scaffold to the lesion to restore the blood flow. Once the vessel blockage is treated and healed, BRS dissolves fully, leaving the artery in its natural state with no foreign residue6.
  4. Drug-eluting balloons (DEB)7DEB (e.g. PACT Falcon) includes-
  • homogenous drug transfer to the entire vessel wall.
  • rapid release of high concentrations of the drug sustained in the vessel wall no longer than a week, with little impact on long-term healing.
  • absence of polymer to decrease chronic inflammation and the trigger for late thrombosis.
  • absence of a stent allows the artery’s original anatomy to remain intact, notably in cases of bifurcation or small vessels, thereby diminishing abnormal flow patterns.
  • local drug delivery which can help curtail overdependence on antiplatelet therapy

How is a stent inserted?

  1. Coronary angioplasty usually takes place in a room called a catheterization laboratory, rather than in an operating theatre.
  2. The room is fitted with X-ray equipment to allow the doctor to monitor the procedure on a screen.
  3. The cardiologist then makes a small incision in the skin of your groin, wrist, or arm, over an artery where your pulse can be felt.
  4. A small tube called a sheath is inserted into the artery to keep it open during the procedure.
  5. A catheter is passed through the sheath and guided along the artery into the opening of your left or right coronary artery.
  6. Then, a thin, flexible wire is then passed down the inside of the catheter to beyond the narrowed area. A small, sausage-shaped balloon is passed over the wire to the narrowed area and inflated for about 20 to 30 seconds. This squashes the fatty material on the inside walls of the artery to widen it. This may be done several times.
  7. While the balloon is inflated, the artery will be completely blocked and the person may have some chest pain. However, this is normal. The pain should go away when the balloon is deflated.
  8. If the catheter moves through the artery, you may feel an occasional missed or extra heartbeat which is also completely normal.
  9. If you’re having a stent inserted, it will be already fitted onto a balloon and opens up as the balloon is inflated. The stent will be left inside your artery after the balloon is deflated and removed.
  10. When the operation is finished, the cardiologist will check that artery is wide enough to allow blood to flow through more easily. This is done by monitoring a small amount of contrast dye as it flows through the artery.
  11. The balloon, wire, catheter, and sheath are then removed and any bleeding is stopped with a dissolvable plug or firm pressure. In some cases, the sheath is left in place for a few hours or overnight before being removed.

Risk Associated with Angioplasty

Angioplasty may provide a less durable treatment for atherosclerosis and can be more prone to restenosis compared to vascular bypass or coronary artery bypass grafting. Drug-eluting balloon angioplasty has significantly less restenosis, late lumen loss, and target lesion revascularization at both short-term and midterm follow-up compared to uncoated balloon angioplasty for femoropopliteal arterial occlusive disease. Angiography is a complicated procedure and before undergoing the person must understand all terms and conditions associated with it and should also go through the doctor’s advice.

Author: 

Ritika Gupta

Ritika Gupta is an MPharm. graduate who is keen on spreading awareness about various unexplored medical fields through her writings.

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