INTRODUCTION OF STENT PROCEDURE
A stent is a small mesh tube that’s used to treat narrow or weak arteries. Arteries are blood vessels that carry blood away from your heart to other parts of your body.
A stent is placed in an artery as part of a procedure called percutaneous coronary intervention (PCI), also known as coronary angioplasty. PCI restores blood flow through narrow or blocked arteries. A stent helps support the inner wall of the artery in the months or years after PCI.
Doctors also may place stents in weak arteries to improve blood flow and help prevent the arteries from bursting.
Stents usually are made of metal mesh, but sometimes they’re made of fabric. Fabric stents, also called stent grafts, are used in larger arteries.
Some stents are coated with medicine that is slowly and continuously released into the artery. These stents are called drug-eluting stents. The medicine helps prevent the artery from becoming blocked again.
INDICATION OF STENT PROCEDURE
Stents are usually necessary when plaque blocks a blood vessel. Plaque is made of cholesterol and other substances that attach to the walls of a vessel.
You may need a stent during an emergency procedure. An emergency procedure is more common if an artery of the heart called a coronary artery is blocked. Your doctor will first place a catheter into the blocked coronary artery. This will allow them to do a balloon angioplasty to open the blockage. They’ll then place a stent in the artery to keep the vessel open.
Stents can also be useful when there’s an aneurysm in your brain.
TYPES OF STENT PROCEDURE
DUAL THERAPY STENT
Dual Therapy Stent (DTS) is the latest type of coronary stent. It is a first-of-its-kind stent therapy designed to not only reduce the likelihood of the re-narrowing of the artery or of having to undergo a repeat procedure, but also help the healing process of the artery. It combines the benefit of DES and bio-engineered stents and is the only stent to contain a drug with active healing technology.
The DTS has coating both inside and outside, which reduces the likelihood of blood clots, inflammation and helps the healing process of the artery.
The stent surface facing the artery wall contains a drug that is released to help stop the artery blocking again without the worry of swelling or an inflammatory response. The drug is delivered from a bioresorbable polymer that will degrade over time.
The side of the stent which faces blood flow is coated with antibodies, which promote natural healing and helps the healthy artery function properly.
Bio-engineered Stent is also known as antibody-coated stent. This type of stent differs from DES because it does not contain a polymer and does not use a drug. As a result, it helps to speed up the cell lining of the artery (endothelialization), promoting natural healing.
The antibody on the stent’s surface attracts circulating Endothelial Progenitor Cells (EPCs) which come from human bone marrow and help speed up the formation of healthy endothelium. This provides rapid coverage over the stent’s surface helping to reduce the risk of early and late thrombosis (blood clots).
DRUG ELUTING STENT
Drug Eluting Stents (DES) are coated with medication that is released (eluted) to help prevent the growth of scar tissue in the artery lining. This helps the artery remain smooth and open, ensuring good blood flow and reduces the chances of the artery re-narrowing or restenosis. However, it also leads to a higher chance of blood clots (stent thrombosis).
Due to a relatively slower healing process, patients implanted with DES must strictly follow their doctor’s recommendation on drug therapy (DAPT) to help reduce risk of stent thrombosis. Current American Heart Association recommendations are for a minimum DAPT therapy of at least 12 months after DES implantation.3
BARE METAL STENT
Bare metal stents are usually stainless steel and have no special coating. They act as scaffolding to prop open blood vessels after they are widened with angioplasty. As the artery heals, tissue grows around the stent, holding it in place. However, sometimes an overgrowth of scar tissue in the arterial lining increases the risk of re-blockage.
A urinary stent is used to hold the ureter open in cases where it has narrowed. Ureters are long tubes that carry urine from the kidneys to the urinary bladder where it is stored until the bladder is emptied. If a urinary stone forms in the ureter, the usual flow of urine from the kidney to the bladder may be obstructed which can cause damage to the kidney.
A urinary stent can be placed inside the ureter to allow the urine to flow out. Stents can be used in this way as a temporary measure to allow normal urinary function until surgery can be performed to remove the stone
ANESTHESIA FOR STENT PROCEDURE
To present the techniques of anesthesia management used during percutaneous carotid interventions involving balloon dilation and stent deployment.
METHODS AND RESULTS:
Two access routes may be used for carotid angioplasty, and the anesthesia techniques for each are different. In the conventional common femoral artery approach, the patient is sedated, heparinized, and ventilated by mask with 100% oxygen; the groin site is anesthetized locally with lidocaine. When the procedure reaches the point of balloon inflation, the patient is awakened, and atropine is administered to block the baroreceptor response. The heparin is not reversed after the procedure. General anesthesia with short-acting nonopioid intravenous anesthetics is preferred for patients undergoing direct puncture of the common carotid artery. The patient is intubated and ventilated with 100% oxygen. Here the patient is awakened after completion of the procedure, at which time protamine sulfate is used if needed to restore coagulation time to normal prior to sheath removal. The anesthesiologist must be vigilant in monitoring hemodynamic and neurological status throughout these carotid interventions, particularly during balloon inflations and after the sheath removal for the cervical approach.
Anesthesia for percutaneous carotid interventions differs from that used for carotid surgery. Protection of the brain from ischemic insult is paramount, and scrupulous attention to physiological factors influencing cerebral blood flow is mandatory. The anesthesiologist plays a crucial role in maintaining hemodynamic stability, adjusting anticoagulation, and monitoring neurological status.
PREOPERATIVE PROCEDURE OF STENT PROCEDURE
Before a scheduled angioplasty, your doctor will review your medical history and do a physical exam. You’ll also have an imaging test called a coronary angiogram to see if your blockages can be treated with angioplasty. A coronary angiogram helps doctors determine if the arteries to your heart are narrowed or blocked.
In a coronary angiogram, liquid dye is injected into the arteries of your heart through a catheter — a long, thin tube that’s fed through an artery from your groin, arm or wrist to arteries in your heart. As the dye fills your arteries, they become visible on X-ray and video, so your doctor can see where your arteries are blocked. If your doctor finds a blockage during your coronary angiogram, it’s possible he or she may decide to perform angioplasty and stenting immediately after the angiogram while your heart is still catheterized.
You’ll receive instructions about eating or drinking before angioplasty. Usually, you’ll need to stop eating or drinking six to eight hours before the procedure is scheduled. Your preparation may be different if you’re already staying at the hospital before your procedure.
Whether the angioplasty is pre-scheduled or done as an emergency, you’ll likely have some routine tests first, including a chest X-ray, electrocardiogram and blood tests.
The night before your procedure, you should:
- Follow your doctor’s instructions about adjusting your current medications before angioplasty. Your doctor may instruct you to stop taking certain medications before angioplasty, such as certain diabetes medications.
- Gather all of your medications to take to the hospital with you, including nitroglycerin, if you take it.
- Take approved medications with only small sips of water.
- Arrange for transportation home. Angioplasty usually requires an overnight hospital stay, and you won’t be able to drive yourself home the next day.
PROCEDURE OF STENT PROCEDURE
There are several ways to insert a stent.
Your doctor usually inserts a stent using a minimally invasive procedure. Your doctor will make a small incision and use a catheter to guide specialized tools through your blood vessels to reach the area that needs a stent. This incision is usually in the groin or arm. One of those tools may have a camera on the end to help your doctor guide the stent.
During the procedure, your doctor may also use an imaging technique called an angiogram to help guide the stent through the vessel.
Using the necessary tools, your doctor will locate the broken or blocked vessel and install the stent. They’ll then remove the instruments from your body and close the incision.
POSTOPERATIVE PROCEDURE OF STENT PROCEDURE
What happens after the procedure?
After you leave the hospital, you should drink plenty of fluids and avoid driving, bathing, and smoking for 1 or 2 days after the procedure. You should also avoid standing or walking for long periods for at least 2 days after the procedure. If you received a stent, you should avoid vigorous exercise for 30 days.
If you had angioplasty with or without stent placement, you will need to take aspirin every day for the rest of your life. If you had a stent placed, you will need to take a blood-thinning medicine or antiplatelet therapy for a year or longer. Your doctor will tell you how and when to take these medicines.
About 35% to 40% of patients who have balloon angioplasty are at risk of more blockages in the treated area. This is called restenosis. Restenosis usually happens within 6 months after balloon angioplasty. Arteries that have stents can re-close, as well. Restenosis occurs in about 20% of patients with stents. If restenosis occurs, patients may need to have another balloon angioplasty or stent procedure.
COMPLICATIONS OF STENT PROCEDURE
Angioplasty is generally safe, but ask your doctor about the possible complications. Risks of angioplasty and stent placement are:
- Allergic reaction to the drug used in a drug-eluting stent, the stent material, or the x-ray dye
- Bleeding or clotting in the area where the catheter was inserted
- Blood clot
- Clogging of the inside of the stent (in-stent restenosis)
- Damage to a heart valve or blood vessel
- Heart attack
- Kidney failure (higher risk in people who already have kidney problems)
- Irregular heartbeat (arrhythmias)
- Stroke (this is rare)