Overview of Thrombectomy
A thrombectomy is a type of medical procedure that is used to remove a blood clot. This process is guided by medical images and uses special tools that can go inside blood vessels.
The procedure is most commonly used in cases of acute cerebral ischemic stroke, which is a type of stroke that happens when blood flow to the brain is blocked. However, it’s also used for removing blood clots in acute myocardial infarction – a medical term for what most people know as a heart attack – and pulmonary embolism, a condition where one or more arteries in the lungs become blocked by a blood clot.
During a mechanical thrombectomy, various methods may be employed. Most commonly, it makes use of therapies that involve a catheter, which is a long, thin tube that doctors can use to treat diseases or perform surgeries without needing to make large incisions. These therapies may include the use of a stent retrieval system which is a small, metal mesh tube used to open up blocked passageways, or direct aspiration, suction of the clot itself. Sometimes, a combined approach is used.
Why do People Need Thrombectomy
A stroke occurs when blood flow to the brain is cut off, which damages the brain cells. In the event of a stroke caused by a clot (ischemic stroke), one of the important treatments we use is called mechanical thrombectomy. This treatment involves physically removing the blood clot that is blocking the blood supply to your brain.
There is a good amount of medical research affirming the effectiveness of mechanical thrombectomy for ischemic stroke. Doctors look at the scales and guidelines to determine if this treatment is suitable for a patient. The guidelines suggest that this treatment should be initiated within 6 hours of the stroke symptoms starting. These guidelines also talk about the patient’s overall health prior to the stroke, the severity of the stroke, and age among other things. However, in specific cases, the treatment can be done up to 24 hours after stroke symptoms started. These guidelines have shown that doing a mechanical thrombectomy can lead to better health outcomes for patients.
Heart attack treatment is different from a stroke. A heart attack occurs when a blood clot blocks blood flow to the heart. However, studies have mixed results on the use of mechanical thrombectomy for treating heart attacks. Earlier studies suggested that mechanical thrombectomy can improve the blood flow and patient outcomes compared to the standard heart attack treatment. But more recent studies did not find any significant improvements in patient health. In addition, one study found an increased risk of stroke when mechanical thrombectomy was used. Because of these latter studies, heart health experts do not usually recommend mechanical thrombectomy as the routine treatment for heart attack patients.
Mechanical thrombectomy can also be considered to treat pulmonary embolism, which is a blood clot in the lungs. The procedure is currently being tested and initial studies suggest it could be a safe and effective treatment for people who are at an intermediate risk from pulmonary embolism. If a patient cannot take or has not responded to other treatments that dissolve the blood clot, or if there is not enough time for these treatments to work, mechanical thrombectomy may be an option.
When a Person Should Avoid Thrombectomy
There several conditions that can prevent the possibility of certain medical procedures. These may include:
An intracranial hemorrhage, which is a bleeding inside the brain.
A large infarct core with minimal penumbra. This in simpler words is a large damaged area in the brain with very little surrounding tissue that could potentially be saved.
A small vessel occlusion, which means a blockage in the tiny vessels that carry blood around the body.
Coagulopathies that can’t be corrected. Coagulopathies are disorders that affect the blood’s ability to clot, which could make a procedure too risky if these can’t be corrected before the procedure.
Elevated blood pressure that cannot be managed. If a person’s systolic (the top number in blood pressure reading) is above 185 mmHg or the diastolic pressure (the bottom number) is above 110 mmHg and it can’t be lowered, this could make a procedure potentially risky.
Equipment used for Thrombectomy
Thrombectomy is a medical procedure which involves removing a blood clot from a vessel. Many types of tools are involved in performing thrombectomy. They include: guide catheters, stent-retrievers, tiny catheters called microcatheters, special catheters designed for suction (aspiration catheters), and equipment for creating suction, known as aspiration pump systems.
Aspiration Catheters
These large, special catheters are used to suction out the blood clot. There are many types from different suppliers. The type of catheter used depends on the patient’s body and where the clot is located. In the case of heart attacks, no one type of aspiration catheter has been found to be strikingly better than the others.
Aspiration Pump
This can be a machine or a large syringe (16 to 20 mL in volume). This device is used to create suction which helps to remove the clot.
Microcatheters/Guidewires
This procedure uses smaller catheters that are passed through the guiding catheter over a wire. This procedure is helpful when dealing with more complex conditions and blockages in the heart and other blood vessels of the body.
Stent Retrieval Tool
Solitaire, a device used in the procedure, uses a stent retriever – a device that places a stent (a tiny tube), attaches it to the clot, and then extracts the blood clot. Studies have shown no significant differences between two types of stent retrievers. Another retriever can be used up to 24 hours after symptoms begin.
Other Devices Used
Some advanced thrombectomy devices remove clots from larger vessels using high-volume suction and self-opening mesh discs. They are recommended for use in blood vessels away from the heart (peripheral vasculature) and in lung arteries. Research has shown that this type of device is safe and effective for certain types of patients with pulmonary embolism (a clot in the lung).
Some systems are designed for removing a significant amount of clot from large vessels. They may use methods like coring, which involves removing the clot from the vein wall. These systems include a catheter and a cover, a coring element, and a bag to collect the clot. The catheter is put forward to the clot, pushed through it, and unsheathed and enlarged. As the catheter is retracted, the coring tool frees the clot from the vessel walls, and the bag at the top of the catheter prevents any parts of the clot from spreading.
Who is needed to perform Thrombectomy?
These are a few of the healthcare professionals that might be involved in your treatment. An interventional radiologist is a doctor who specializes in diagnosing and treating various problems using imaging technology. An interventional neurosurgeon is a doctor who performs complex surgeries on the nervous system with the help of advanced imaging techniques. An interventional cardiologist, on the other hand, focuses on treating heart-related problems using similar methods.
The endovascular nurse and technician, meanwhile, are trained in the process of treating problems inside your blood vessels. Your nurse will provide care and support throughout your entire treatment. Lastly, an anesthesiologist and anesthetist are doctors who use medicines to ensure you don’t feel pain during your procedure. They monitor your vital signs and adjust the medications as needed to keep you comfortable.
How is Thrombectomy performed
When someone has a blood clot, or a thrombus, a doctor may perform a procedure called mechanical thrombectomy to remove it. The steps can vary a bit depending on the specifics of the procedure, but there are common steps. You can think of this procedure like a journey through a pipe to remove a blockage. The starting point is usually a small hole in the groin. First, the doctor puts in something called a balloon-guided catheter. This is a sort of flexible tube that the doctor feeds through the body until it reaches the clot.
Next, the doctor pushes a thin metal wire (guidewire) through the clot and slides a smaller tube (microcatheter) along the wire until it also passes through the clot. After this, the guidewire is removed and a special type of stent, which can be retrieved later, is put in place. This stent opens up and grips onto the clot, a bit like an anchor. To double-check their work, doctors then inject some contrast dye through the initial balloon catheter to see the blood flow past the clot under X-ray. Then, they inflate the balloon to temporarily stop the blood flow while they pull out the stent, clot, and microcatheter slowly.
There’s also an alternate method to remove the clot, called the ADAPT technique. This method uses suction from a pump or a big syringe applied through a large catheter to try and pull the clot out directly. If the doctors aren’t able to get the clot out this way, they may attempt this several times or use other methods, like a stent retriever. This just shows how doctors are always finding innovative ways to make these procedures safer and more effective.
Possible Complications of Thrombectomy
When you have surgery to remove a blood clot in your brain, known as a mechanical thrombectomy, there are certain risks involved. One such risk is a condition called symptomatic intracerebral hemorrhage, which is a type of bleeding in the brain that can happen due to the instruments used during the surgery. However, it’s worth noting that the chance of this kind of bleeding isn’t really higher than it is with other standard medical treatments.
Other complications can also arise from a thrombectomy. For example, a clot could move and get stuck somewhere else in your brain. The area where the clot was removed could become narrow or blocked again. The blood vessels could get damaged or torn during the procedure. You might also get a bruise or collection of blood in areas like the groin or behind the belly where the puncture for the operation was made. The clot might return due to a high number of platelets (blood cells that help your body form clots) when you are admitted, a previously existing narrowing of the blood vessel, or leftover clot around the site where it was removed.
While these complications don’t happen often, if they do, they can indicate that the patient’s health may not improve well after surgery.
What Else Should I Know About Thrombectomy?
Removing a blood clot lodged in a large blood vessel (termed a ‘mechanical thrombectomy’) is often the main treatment for large vessel occlusions. There was a significant study in 2015 called the MR CLEAN trial, which took place in the Netherlands and involved many different medical centers. The study aimed to compare stroke patients who received regular care and a special blood vessel treatment to those who only received standard care.
The blood vessel treatment, which involved mechanical thrombectomy, helped more patients recover and live independently after a severe stroke. A total of 13.5% more patients who had this treatment became functionally independent compared to those who didn’t. This suggests that such blood vessel treatments are safe and effective. Nonetheless, additional studies have found that there may be a risk of bleeding in the brain (intracranial hemorrhage) due to complications during the procedure, which remains a concern.
Other benefits of this treatment include improvements in the quality of life and thinking skills in long-term follow-ups after a stroke. Hence, this treatment is an essential option to consider for individuals experiencing a severe type of stroke called ischemic stroke.