Overview of Thrombectomy
A thrombectomy is a procedure where doctors use medical tools to carefully remove a blood clot. This is done under the guide of images or scans. Thrombectomy is often used in emergency situations where there’s a stroke caused by a blockage in the brain. But it can also be used when there’s a clot in the heart (a condition called acute myocardial infarction) or the lungs (known as pulmonary embolism).
This procedure uses multiple techniques and special tubes called catheters. Different methods of removing the clot are used which could include a stent-retrieval (a process where a small tube known as a stent is used to capture the clot), direct aspiration (a process where the clot is sucked out), or a combination of both.
Why do People Need Thrombectomy
If someone has a stroke that is caused by a blockage in an artery in their brain (also known as an ischemic stroke), a procedure called a mechanical thrombectomy can be used to remove the blockage. The main goal of this procedure is to save the brain tissue at risk of dying from the blockage. Scientific research has shown that this procedure works better than clot-busting drugs that are given through a vein. The overall effectiveness of mechanical thrombectomy has prompted the rules for deciding when to use it to change. For example, it can still be beneficial up to 24 hours after the stroke happened.
A set of criteria helps doctors to decide when to use the procedure. These include things like the person’s overall level of disability before they had the stroke should be low, the severity of the stroke symptoms which should be moderate or severe, and the procedure should start within 6 hours of the start of stroke symptoms. Ideally, brain scans show that the blockage is in a major artery in the brain. The patient also needs to be 18 years or older.
In contrast, using mechanical thrombectomy in a heart attack situation is not so clear cut. Early research suggested that using the procedure to remove a clot that is causing a heart attack could help improve blood flow and survival rates. But, more recent studies showed that the procedure did not really improve patient outcomes. In fact, it might even increase the risk of stroke in the 30 days following the heart attack. This has led the American Heart Association to downgrade its recommendation for using mechanical thrombectomy in heart attacks.
Regarding using mechanical thrombectomy in cases of pulmonary embolism, a condition where a blood clot blocks one of the arteries in the lungs, research is still ongoing. Early clinical trials suggest that the procedure can be safe and effective in certain people with acute moderate-risk pulmonary embolism. It might be a good option for people who can’t be given clot-busting drugs because of a high risk of bleeding or limited time.
When a Person Should Avoid Thrombectomy
There are several reasons why a person might not be able to undergo specific medical procedures. For instance:
If a person has bleeding inside their skull (intracranial hemorrhage), that could make any intervention very risky.
If a person has had a large stroke (large infarct core) with only a little bit of brain tissue that might recover (minimal penumbra), this can be a roadblock to several treatments.
Small blood vessels can sometimes get blocked (small vessel occlusion). When this happens, certain procedures might not work or could be too dangerous.
If a person has a problem that affects their blood’s ability to clot (coagulopathies), and it can’t be corrected, this can make some treatments too risky.
High blood pressure, specifically when the pressure when the heart is at rest (diastolic pressure) is over 110 mmHg or the pressure when the heart is contracting (systolic pressure) is over 185 mmHg, can also prevent some treatments if it can’t be brought under control.
Equipment used for Thrombectomy
Thrombectomy, or the removal of a blood clot from a blood vessel, involves the use of several specialized devices. These include guide catheters, stent-retrievers, tiny catheters called microcatheters, suction tubes called aspiration catheters, and aspiration pump systems.
Aspiration Catheters
Large-bore catheters are used to suck the blood clot out using a vacuum-like effect. There are numerous aspiration catheters available from various manufacturers. The choice of which one to use depends on the patient’s body and where the clot is located. For heart attacks (MI), it’s not clear if one type of aspiration catheter is significantly better than another.
Aspiration Pump
This machine, or a large syringe ranging from 16 to 20 mL, is used to create a vacuum (negative pressure) that helps to suck out the clot.
Microcatheters/ Guidewires
These small catheters are moved into a larger guide catheter with the help of a wire. They’re especially useful for tackling intricate and completely blocked blood vessels in the heart and limbs.
Stent Retrieval Tool
The Solitaire device uses a stent retrieval tool. This expandable mesh tube attaches itself to the clot and then helps to pull it out. Studies have shown that there’s no significant difference in effectiveness or safety between two different types of these tools. Another type of stent retriever can be used in patients showing symptoms for up to 24 hours.
Other Devices Used
There are also other innovative blood clot removal devices that work by suctioning out clots in large vessels or using self-expanding mesh discs. One such device can be used in the peripheral blood vessels and lung arteries. The FLARE study showed that these devices are safe and effective in treating acute, intermediate-risk patients with a lung embolism (PE).
Also used are “over the wire systems,” which can remove a significant amount of clot from large diameter vessels. They work by carving out the clot from the vein walls. These systems include a catheter and a sheath. The catheter has a coring element to release the clot and a collecting bag to ensure no pieces of the clot spread elsewhere in the body.
Who is needed to perform Thrombectomy?
These are all medical professionals who have specialized skills related to different types of surgeries and procedures. An interventional radiologist, for example, uses imaging techniques like X-rays to see inside our body and treat conditions. An interventional neurosurgeon is a specialized surgeon who operates on the brain and nervous system, while an interventional cardiologist focuses on the heart and blood vessels.
There are also endovascular nurses and technicians who play a crucial role in your treatment. They assist with procedures that involve your blood vessels. Anesthesia personnel, which include anesthesiologists (doctors specialized in providing anesthesia) or anesthetists, are responsible for any medicines that are needed during the procedure to keep you asleep and without pain. Each of these professionals will work together to ensure your procedure goes as smoothly and safely as possible.
How is Thrombectomy performed
Mechanical thrombectomy is a procedure used to remove a blood clot from the body, and the way it’s done can slightly differ based on the specifics of each case. Generally, it starts with the doctor inserting a type of tube called a balloon-guided catheter, usually, this is done through a small puncture in the groin. They then guide this catheter through the body until it reaches the blood clot.
Next, a thin wire called a guidewire is pushed through the blood clot, and a thin tube called a microcatheter is slid over the guidewire. After this, the guidewire is taken out and a stent, which is a small mesh tube, is put in place. This stent opens up and grips the blood clot, holding it securely to the stent. From there, a special dye is injected to allow doctors to check the flow of blood past the clot.
Once it’s confirmed that blood is flowing correctly, the balloon is inflated temporarily to stop the blood flow. Simultaneously, the stent and microcatheter, together with the clot, are slowly pulled out through the catheter while suction is applied. Finally, a second check is done using an image to make sure the clot has been entirely removed.
There’s also a different method called ADAPT (A Direct Aspiration First Pass Technique), which instead of using a stent to grip the clot, uses suction. In this technique, a large tube is advanced to the clot level, utilizing a fine wire and small tube. Then, suction is applied using a pump or syringe. If the suction meets resistance, that means the tube has reached the clot.
The tube is then advanced slightly to surround the clot, and suction is applied again. The success of the clot retrieval is tested by watching for a stop in suction resistance. If the clot isn’t retrieved, further attempts and other tools such as a stent retriever are quickly used to remove the clot.
Possible Complications of Thrombectomy
When a doctor performs a procedure called a mechanical thrombectomy to treat a stroke, there can be some risks involved. One of these risks includes symptomatic intracerebral hemorrhage, which is when bleeding happens inside the brain. This can occur as a result of the instruments used during the surgery. However, it’s important to note that this risk is not higher than the normal medical treatment for stroke.
Some other issues that could arise during this procedure are dislodging of a clot, which could travel from the original blockage point to other parts of the body. The place where the clot was removed may become narrow again, which could lead to more complications. Sometimes, the blood vessel being treated may get punctured or torn.
At the site where the doctor made a small cut to access your blood vessels, which is usually in the groin, there could be pooling of blood, known as hematomas. The treated blood vessel could become blocked again due to a high number of platelets – the blood cells that help with clotting – a pre-existing narrowing of the blood vessel, or particles left behind from the clot.
Even though these complications don’t happen often, if they do, they can lead to worse health outcomes. However, it’s important to remember that all medical procedures come with certain risks, and your doctor will always weigh the benefits of the treatment against these risks.
What Else Should I Know About Thrombectomy?
One of the ways to treat a large blockage in a blood vessel is through a procedure called mechanical thrombectomy. It’s a common procedure often used for serious cases. In a scientific study done in the Netherlands, named the ‘MR CLEAN trial,’ researchers looked at the differences in recovery between patients who had this treatment alongside regular care and those who only had standard medical treatment.
The procedure involves reopening the blocked vessel using a small device, which leads to improved blood flow. The study found that, after suffering a stroke, 13.5% more patients who underwent this treatment were able to live independently compared to those who had standard care, showing that this procedure is both safe and effective.
However, more research has shown that there can be a risk of internal bleeding due to complications during the procedure, which is something that doctors need to consider. Those who received this treatment also showed improvements in terms of their quality of life and mental abilities in the long run.
