Overview of Percutaneous Coronary Intervention
Coronary artery disease (CAD), a condition where the heart’s major blood vessels are damaged, is one of the top causes of death. One way to treat CAD is through a procedure called Percutaneous Coronary Intervention (PCI). This is not a surgery, but it does involve applying tools to the body.
The goal of PCI is to address the issue of the narrowed or blocked coronary artery. The coronary artery is extremely important because it supplies blood to the heart. If it’s blocked, parts of the heart can’t get the oxygen-rich blood they need, a condition called ischemic tissue.
There are various ways to perform PCI, but the most common methods are balloon angioplasty and stent placement. Balloon angioplasty involves a small balloon, attached to a long, thin tube called a catheter, being inflated at the site of the blockage. This helps widen the narrowed artery. Stent placement, on the other hand, involves placing a small mesh tube within the artery to keep it open. This way, blood can flow freely to the heart again.
Anatomy and Physiology of Percutaneous Coronary Intervention
Access to the bloodstream is typically achieved through a major artery like the artery in the groin (femoral) or the artery in the wrist (radial). A real-time X-ray method called fluoroscopy is used to clearly see the catheter (a thin tube) and the tissues within the body. The catheter is carefully advanced to the aorta, which is the main blood vessel that supplies blood to the body.
Special catheters are then used to access the coronary arteries – these are the vessels that supply blood to the heart. A substance known as an IV contrast is then introduced into the coronary artery. This contrast acts like a dye, highlighting the structure of the coronary arteries and making them easy to see on an X-ray.
Pictures, or X-ray images, of these arteries are then taken from various angles. This helps the doctor understand the three-dimensional structure of any coronary artery narrowing, which can restrict blood flow to the heart.
Why do People Need Percutaneous Coronary Intervention
There are certain situations where the doctor might suggest undergoing a procedure known as percutaneous coronary intervention, or PCI. This procedure is often used to restore blood flow to the heart.
One such situation is if you have a medical condition called acute ST-elevation myocardial infarction, also known as STEMI. This is a severe type of heart attack in which a blood vessel in your heart is completely blocked. If you’re experiencing symptoms of a heart attack — such as intense chest pain — for less than 12 hours, your doctor may recommend you for a PCI. This procedure can be particularly beneficial if you have a blockage amounting to more than 50% in one of the blood vessels of your heart.
Another situation where doctors might perform a PCI is in cases of non-ST-elevation acute coronary syndrome (NSTE-ACS). This condition is a type of heart attack where the blood flow in your heart’s arteries is severely reduced, but not completely blocked. In such cases, an early intervention (within 2 hours of experiencing symptoms) is usually recommended by doctors. Some signs that might suggest you need early intervention include stubborn or recurring chest pain, symptoms of heart failure, new onset or worsening problems with your heart’s valves, or a drop in your blood pressure. If you have unstable levels of a heart protein called troponin, this could be another sign that you need early intervention (within 24 hours).
Unstable angina, a type of chest pain, is another condition that might call for a PCI. Additionally, if you have stable angina — a chest pain that occurs with exertion and goes away with rest — doctors may recommend this procedure. Sometimes, heart disease symptoms aren’t typical and you might experience shortness of breath, abnormal heart beats, dizziness, or fainting instead of chest pain, a situation known as anginal equivalent that may require PCI.
You might also be recommended for a PCI if you have unusually high-risk findings from a stress test, which measures how your heart works during physical activity. Finally, if you have a significant narrowing in one of your coronary arteries and aren’t eligible for a more invasive procedure called coronary artery bypass surgery (CABG), your doctor might suggest a PCI.
When a Person Should Avoid Percutaneous Coronary Intervention
There are some definite reasons why certain people should not have a certain procedure, including:
1. If someone is unable to follow the procedure or unable to take a combination of two medicines that prevent their blood from clotting (dual antiplatelet therapy).
2. If there’s a high chance of them bleeding during the procedure because of a lack of enough blood platelets (thrombocytopenia), stomach ulcers, or severe bleeding disorders (severe coagulopathy).
3. If the person has previously tried to open blocked arteries in the heart multiple times, but the procedure has been unsuccessful (multiple percutaneous coronary intervention restenosis).
These are the reasons why the procedure might be inadvisable but not completely ruled out:
1. If someone cannot take the oral antiplatelet medication for a long term.
2. If the surgical team that specializes in heart surgeries is not immediately available should there be any complications.
3. If the person has a higher than usual chance of blood clots forming in their body (hypercoagulable state).
4. If the person has severely damaged kidneys (high-grade chronic kidney disease).
5. If the person has a complete blockage of the vein that’s used as a graft during heart bypass surgery (chronic total occlusion of SVG).
6. if the artery is too small (less than 1.5 mm in diameter) for the procedure.
7. If only less than half of the artery is blocked (stenosis of less than 50%).
8. If the left main artery of the heart, which supplies most of the blood to the heart, is critically narrowed, with no alternative routes for blood to reach the heart, or a functioning bypass graft in place.
Equipment used for Percutaneous Coronary Intervention
Percutaneous coronary intervention is a nonsurgical procedure that is done during an angiogram to open blocked or narrowed coronary arteries. An angiogram is simply a special type of X-ray used to study the blood vessels. Depending on the particular needs, different equipment might be used including:
- Introducer needle: this is used to make an initial entry into the body.
- Sheath introducer: a device that helps to guide and support other tools like catheters.
- Guide catheters: these are used to reach the area in the body where treatment is required.
- Radioopaque dye (IV contrast): This is a special dye that helps the doctors to see the blood vessels more clearly.
- Guidewire: provides a pathway for other devices to follow.
- Balloon catheter: A small flexible tube that uses a balloon to open up blockages in the blood vessels.
- Stents: Small tubes used to support the blood vessels. They come in different types:
- Bare metal stents (BMS): Best for patients who cannot take blood thinning medicines for a long time. At least 1 month of these medicines is required after this type of stent.
- Drug-eluting stents (DES): These are better at reducing the chances of the blood vessels getting blocked again compared to BMS.
- Bioresorbable vascular scaffold (BVS) and Drug-eluting balloons (DEB) are other types of equipment which might be used.
- Thrombus aspiration: this is a technique used to remove clots but is not needed in all cases.
- Atherectomy devices like the rotational or laser, cutting balloons, and radiation beads lithoplasty/lithotripsy systems can also be used.
The time it takes from when a patient arrives at the hospital to when the balloon is inflated during the angiogram is known as ‘door-to-balloon time’ (D2B time). This measure is used to improve how soon a patient with a severe type of heart attack known as STEMI (ST-elevation myocardial infarction) can receive treatment. Studies have shown that the shorter this time, the better the patient’s chances of surviving while in hospital.
An angiogram can be performed through accessing the radial artery in the wrist, or the femoral artery in the thigh. Generally, the radial approach is preferred as the risk of bleeding from the site is lower. This is because the radial artery is closer to the surface and can be easily compressed against the bone. However, this requires more skills because the radial artery is small.
Before using the radial artery, the doctor must check if blood flow to the hand is good to avoid complications. A large study in 2016 showed that patients who had the procedure done through the radial approach had fewer complications including major bleeding, death, and significant heart-related events.
Preparing for Percutaneous Coronary Intervention
Patients undergoing a Percutaneous Coronary Intervention (PCI) – a non-surgical procedure used to treat narrowing of the coronary arteries – usually receive a set of drugs known as antiplatelet therapy. This therapy helps to prevent blood clots that may lead to heart attacks. Some of the medicines and dosages used in this treatment include:
1. Aspirin: Given in a dose of 162 to 325 mg on the day of the procedure.
2. Unfractionated heparin: Used at the time of the procedure.
3. Glycoprotein IIb/IIIa inhibitors: Medicines like abciximab, tirofiban, and eptifibatide, which have been shown to reduce complications during the procedure.
4. Dual antiplatelet therapy (DAPT): A combination of low dose aspirin (usually 81mg), and a P2Y12 inhibitor (like clopidogrel, prasugrel, or ticagrelor).
How long a patient needs to stay on the dual antiplatelet therapy after the procedure depends on the patient’s overall condition:
1. Acute Coronary Syndrome patients (heart conditions like heart attacks) who underwent PCI: They continue the therapy for a minimum of 1 year, regardless of the type of stent used.
2. Patients with stable ischemic heart disease (a condition where the heart muscle doesn’t get enough blood), who underwent PCI: The therapy is continued for
* At least 1 month if Bare Metal Stents (BMS) were used.
* At least 6 months if Drug-Eluting Stents (DES) were used.
The therapy may be interrupted earlier in patients with a high bleeding risk:
1. Patients with ACS who had PCI can reasonably stop after 6 months.
2. Patients with SIHD who had PCI with DES can reasonably stop after 3 months.
3. Patients with SIHD who had PCI with BMS can reasonably stop after 1 month.
However, any changes to your drug regimen should be discussed and performed under the supervision of your healthcare provider.
How is Percutaneous Coronary Intervention performed
Angiography is a procedure used to examine the blood vessels in your body, specifically to locate and gauge the severity of any blockages or narrowing segments, normally due to a buildup of fatty materials. It’s usually done by inserting a small tube or needle into an artery, commonly in the groin area. A special wire is then passed through this tube, which helps maintain an opening in the artery.
A sheath, which is a flexible hollow tube, is then inserted into the opening. This is used to guide different types of catheters (slender tubes) to different locations in the body. Using X-ray technology, a type of dye is then introduced to the artery which helps visualise its structure. If a blockage is found, the doctor can then guide a tiny wire all the way to the blockage in the artery.
This tiny wire is then used to guide a catheter with a small balloon or a stent (a small mesh tube) for the next step of the procedure, depending on what is needed. If a balloon is needed, the balloon is inflated at the blockage site to help widen the artery. If a stent is needed, once it’s in the right place, the tiny balloon is inflated and the stent expands over the balloon, then once the balloon is deflated and removed, the stent remains in place to help keep the artery open.
There are mainly two methods for placing the stent: direct stenting or pre-inflation followed by stenting. Direct stenting involves placing the stent directly into the narrowing segment of the artery without pre-inflation. The other method involves inflating a balloon in the narrowed segment at first, followed by the placement of the stent. Both techniques have been found to be effective in different situations.
There are other techniques doctors can use to clear arteries, such as atherectomy, where hard deposits in the arteries are cut away with a burr or crown. Similarly, brachytherapy involves the use of radiation to prevent an artery narrowing again and is specifically used for preventing a stented artery from clogging up again. These techniques show promise but are not routinely used for all patients.
Your doctor will decide what method is best for you depending on your specific condition and needs. It’s important to know that while these procedures are generally successful, complications can occur. However, these techniques have significantly improved the outcomes for patients with blocked blood vessels, offering a less invasive option than open surgery.
Possible Complications of Percutaneous Coronary Intervention
There are certain risks associated with heart-related procedures such as coronary artery procedures or aortic injuries. Here are some possible complications:
1. Dissection or Rupture: The lining of your artery could separate or your artery could break open.
2. Bleeding: You might bleed from the place where doctors inserted medical instruments. This could be in your groin (if they used the femoral approach) or your wrist (if they used the radial approach). The bleeding could be either outside your body or inside it.
3. Infection: There’s a chance of developing an infection at the site where doctors inserted medical instruments. There’s also a risk of a systemic infection, which means bacteria could get into your bloodstream after your procedure.
4. Renal Failure: The contrast (a type of dye) doctors use in some imaging tests might make kidney function worse, especially if you already have kidney problems.
5. Stroke: There’s a risk of stroke from blood clots that might form during the procedure.
6. Heart attack: You could have a heart attack from a dissection or a blockage. The blockage could occur within a stent (a small mesh tube that’s used to treat narrow or weak arteries) or lower down in the artery from plaque debris.
The risk of complications increases with certain factors such as being older than 65, being female, having kidney dysfunction, diabetes, systolic heart disease (a condition in which the heart doesn’t pump blood properly), extensive coronary artery disease, or a low body mass index (a measure that helps healthcare providers determine if a person’s weight could lead to health problems).
What Else Should I Know About Percutaneous Coronary Intervention?
Percutaneous coronary intervention (PCI) is a procedure used to open up blocked arteries in your heart. It has been widely used for several years now, and 80% of the time, it’s done with the help of tiny mesh tubes called stents. Over the last two decades, this procedure has greatly helped reduce the risk of death, heart attack, and the need for repeat procedures in patients.
When deciding the best treatment option for heart disease, we look at different clinical trials and use a tool called the SYNTAX score. This score indicates the seriousness of the blockages in the arteries and aids in choosing between treatments like PCI or Coronary Artery Bypass Grafting (CABG – a type of surgery that improves blood flow to the heart).
Now, let’s compare PCI and CABG:
– CABG is usually the better option for patients with high SYNTAX scores, meaning those with serious blockages in two or three heart arteries.
– CABG is also preferred if the main artery on the left side of the heart is diseased or if one or two arteries have blockages, and the SYNTAX score is low.
– CABG seems to work better compared to PCI in patients with diabetes who have blockages in multiple vessels.
– A particular type of CABG, where the surgeon uses a chest wall artery (Left Internal Mammary Artery or LIMA) to bypass the diseased portion of the most important artery of the heart (Left Anterior Descending artery or LAD) offers greater survival benefits.
Comparing PCI with regular medication:
– If a patient has mild chest pain (angina), high-dose statin medications might be a better choice than a procedure like balloon angioplasty (a technique used to widen the blocked artery).
– On the other hand, PCI is chosen over medications if the patient has severe symptoms, isn’t responding to medications, has serious blockages, or if the heart’s pumping ability (Left Ventricular or LV function) is declining rapidly.
