Thrombectomy

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Mechanical thrombectomy, or simply thrombectomy, is the removal of a blood clot (thrombus) from a blood vessel, often and especially endovascularly as an interventional radiology procedure called endovascular thrombectomy (EVT). It thus contrasts with thrombolysis (clot dissolution) by thrombolytic medications (e.g., alteplase, reteplase), as either alternative or complement thereto. It is commonly performed in the cerebral arteries (interventional neuroradiology) as treatment to reverse the ischemia in some ischemic strokes (i.e., those in which the blockage is a suitable candidate for such retrieval). Open vascular surgery versions of thrombectomy also exist. The effectiveness of thrombectomy for strokes was confirmed in several randomised clinical trials conducted at various medical centers throughout the United States, as reported in a seminal multistudy report in 2015. [1]

Contents

Applications in brain

Ischemic stroke represents the fifth most common cause of death in the western world and the number one cause of long-term disability. Until recent times, systemic intravenous fibrinolysis was the only evidence-based therapy for patients with acute onset of stroke due to large vessel occlusion.

In 2015, the results of five trials from different countries were published in the New England Journal of Medicine , demonstrating the safety and efficacy of mechanical thrombectomy with stent-retrievers in improving outcomes and reducing mortality for patients who present within six hours from their time last known well. It is now a widespread procedure performed in many hospitals around the globe, especially comprehensive stroke centers, although many other hospitals are not yet able to supply the service enough to meet the need. [2] Large obstacles to making EVT more widely available are both systematic hurdles at the prehospital stages [2] and the intrahospital barrier of a scarcity of interventional neuroradiologists. [2] [3] They concern TTR (time to reperfusion), which is the same underlying problem as the golden hour in general, albeit several hours in the case of TTR: that is, EVT performed within 2 or 3 hours can help vastly, whereas EVT performed after 6 to 12 hours is often (although not always) too late to prevent the permanent sequelae of the ischemia. [2] In this respect, the dissemination of EVT into clinical practice shows how translational medicine has various layers, some easier to solve and some harder: it was in some respects straightforward to develop the technology of EVT in the 2000s and 2010s (that is, the catheter tips and procedures), [2] but it is not easy to revamp the standard of care in prehospital settings (such as awareness among family members and bystanders, optimal techniques for emergency medical services, and so on), [2] which deployment of timely EVT requires. [2]

In 2018 the DAWN and DEFUSE-3 trials were published. These trials showed that mechanical thrombectomy is a safe and effective treatment for individuals who have an acute ischemic stroke, even (in some cases) out to 24 hours after symptom onset. [4] [5] Most studies, however, have focused on thrombectomies in anterior circulation strokes. In recent years, increasing evidence on the efficacy of mechanical thrombectomy in posterior circulation strokes has been published. [6]

Stent-retriever thrombectomy

The procedure can be performed with general anesthesia or under conscious sedation in an angiographic room. A system of coaxial catheters is pushed inside the arterial circulation, usually through a percutaneous access to the right femoral artery. A microcatheter is finally positioned beyond the occluded segment and a stent-retriever is deployed to catch the thrombus; finally, the stent is pulled out from the artery, usually under continuous aspiration in the larger catheters.[ citation needed ]

Direct aspiration

A different technique for mechanical thrombectomy in the brain is direct aspiration. It is performed by pushing a large soft aspiration catheter into the occluded vessel and applying direct aspiration to retrieve the thrombus; it can be combined with the stent-retriever technique to achieve higher recanalization rates, but the complexity of the procedure increases.[ citation needed ]

Direct aspiration has not been studied as thoroughly as stent-retriever thrombectomy, but it is still widely performed because of its relative simplicity and low cost.[ citation needed ]

Delivery

Patients in London who suffered stroke were found to be much more likely to get thrombectomy in 2022 than those in other parts of England. 42% of thrombectomy units only operated during office hours and Monday to Friday, largely due to a shortage of neurointerventionalists. [3]

See also

Related Research Articles

<span class="mw-page-title-main">Angioplasty</span> Procedure to widen narrow arteries or veins

Angioplasty, also known as balloon angioplasty and percutaneous transluminal angioplasty (PTA), is a minimally invasive endovascular procedure used to widen narrowed or obstructed arteries or veins, typically to treat arterial atherosclerosis.

<span class="mw-page-title-main">Thrombosis</span> Formation of blood clots inside the blood vessels

Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets (thrombocytes) and fibrin to form a blood clot to prevent blood loss. Even when a blood vessel is not injured, blood clots may form in the body under certain conditions. A clot, or a piece of the clot, that breaks free and begins to travel around the body is known as an embolus.

<span class="mw-page-title-main">Interventional radiology</span> Medical subspecialty

Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs both diagnostic and therapeutic procedures through very small incisions or body orifices. Diagnostic IR procedures are those intended to help make a diagnosis or guide further medical treatment, and include image-guided biopsy of a tumor or injection of an imaging contrast agent into a hollow structure, such as a blood vessel or a duct. By contrast, therapeutic IR procedures provide direct treatment—they include catheter-based medicine delivery, medical device placement, and angioplasty of narrowed structures.

<span class="mw-page-title-main">Thrombolysis</span> Breakdown (lysis) of blood clots formed in blood vessels, using medication

Thrombolysis, also called fibrinolytic therapy, is the breakdown (lysis) of blood clots formed in blood vessels, using medication. It is used in ST elevation myocardial infarction, stroke, and in cases of severe venous thromboembolism.

<span class="mw-page-title-main">Vascular surgery</span> Medical specialty, operative procedures for the treatment of vascular disorders

Vascular surgery is a surgical subspecialty in which vascular diseases involving the arteries, veins, or lymphatic vessels, are managed by medical therapy, minimally-invasive catheter procedures and surgical reconstruction. The specialty evolved from general and cardiovascular surgery where it refined the management of just the vessels, no longer treating the heart or other organs. Modern vascular surgery includes open surgery techniques, endovascular techniques and medical management of vascular diseases - unlike the parent specialities. The vascular surgeon is trained in the diagnosis and management of diseases affecting all parts of the vascular system excluding the coronaries and intracranial vasculature. Vascular surgeons also are called to assist other physicians to carry out surgery near vessels, or to salvage vascular injuries that include hemorrhage control, dissection, occlusion or simply for safe exposure of vascular structures.

<span class="mw-page-title-main">Interventional cardiology</span> Catheter-based treatment of structural heart diseases

Interventional cardiology is a branch of cardiology that deals specifically with the catheter based treatment of structural heart diseases. Andreas Gruentzig is considered the father of interventional cardiology after the development of angioplasty by interventional radiologist Charles Dotter.

<span class="mw-page-title-main">Cerebral angiography</span> Angiography that produces images of blood vessels in and around the brain

Cerebral angiography is a form of angiography which provides images of blood vessels in and around the brain, thereby allowing detection of abnormalities such as arteriovenous malformations and aneurysms. It was pioneered in 1927 by the Portuguese neurologist Egas Moniz at the University of Lisbon, who also helped develop thorotrast for use in the procedure.

<span class="mw-page-title-main">Cerebral infarction</span> Stroke resulting from lack of blood flow

Cerebral infarction, also known as an ischemic stroke, is the pathologic process that results in an area of necrotic tissue in the brain. In mid to high income countries, a stroke is the main reason for disability among people and the 2nd cause of death. It is caused by disrupted blood supply (ischemia) and restricted oxygen supply (hypoxia). This is most commonly due to a thrombotic occlusion, or an embolic occlusion of major vessels which leads to a cerebral infarct. In response to ischemia, the brain degenerates by the process of liquefactive necrosis.

<span class="mw-page-title-main">Percutaneous coronary intervention</span> Medical techniques used to manage coronary occlusion

Percutaneous coronary intervention (PCI) is a minimally invasive non-surgical procedure used to treat narrowing of the coronary arteries of the heart found in coronary artery disease. The procedure is used to place and deploy coronary stents, a permanent wire-meshed tube, to open narrowed coronary arteries. PCI is considered 'non-surgical' as it uses a small hole in a peripheral artery (leg/arm) to gain access to the arterial system, an equivalent surgical procedure would involve the opening of the chest wall to gain access to the heart area. The term 'coronary angioplasty with stent' is synonymous with PCI. The procedure visualises the blood vessels via fluoroscopic imaging and contrast dyes. PCI is performed by an interventional cardiologists in a catheterization laboratory setting.

Animal models of ischemic stroke are procedures inducing cerebral ischemia. The aim is the study of basic processes or potential therapeutic interventions in this disease, and the extension of the pathophysiological knowledge on and/or the improvement of medical treatment of human ischemic stroke. Ischemic stroke has a complex pathophysiology involving the interplay of many different cells and tissues such as neurons, glia, endothelium, and the immune system. These events cannot be mimicked satisfactorily in vitro yet. Thus a large portion of stroke research is conducted on animals.

<span class="mw-page-title-main">Carotid stenting</span>

Carotid artery stenting is an endovascular procedure where a stent is deployed within the lumen of the carotid artery to treat narrowing of the carotid artery and decrease the risk of stroke. It is used to treat narrowing of the carotid artery in high-risk patients, when carotid endarterectomy is considered too risky.

Embolectomy is the emergency interventional or surgical removal of emboli which are blocking blood circulation. It usually involves removal of thrombi, and is then referred to as thromboembolectomy or thrombectomy. Embolectomy is an emergency procedure often as the last resort because permanent occlusion of a significant blood flow to an organ leads to necrosis. Other involved therapeutic options are anticoagulation and thrombolysis.

<span class="mw-page-title-main">Left atrial appendage occlusion</span> Medical treatment

Left atrial appendage occlusion (LAAO), also referred to as left atrial appendage closure (LAAC), is a procedure used to reduce the risk of blood clots from the left atrial appendage entering the bloodstream and causing a stroke in those with non-valvular atrial fibrillation.

<span class="mw-page-title-main">Acute limb ischaemia</span> Occurs when there is a sudden lack of blood flow to a limb

Acute limb ischaemia (ALI) occurs when there is a sudden lack of blood flow to a limb, within 14 days of symptoms onset. It is different from another condition which is more chronic called critical limb ischemia (CLD). CLD is the end stage of peripheral vascular disease where there is still some collateral circulation (alternate circulation pathways} that bring some blood to the distal parts of the limbs. While limbs in both acute and chronic limb ischemia may be pulseless, a chronically ischemic limb is typically warm and pink due to a well-developed collateral artery network and does not need emergency intervention to avoid limb loss.

<span class="mw-page-title-main">Endovascular coiling</span> Medical treatment for aneurysm

Endovascular coiling is an endovascular treatment for intracranial aneurysms and bleeding throughout the body. The procedure reduces blood circulation to the aneurysm through the use of microsurgical detachable platinum wires, with the clinician inserting one or more into the aneurysm until it is determined that blood flow is no longer occurring within the space. It is one of two main treatments for cerebral aneurysms, the other being surgical clipping. Clipping is an alternative to stenting for bleeding.

Interventional neuroradiology (INR) also known as neurointerventional surgery (NIS), endovascular therapy (EVT), endovascular neurosurgery, and interventional neurology is a medical subspecialty of neurosurgery, neuroradiology, intervention radiology and neurology specializing in minimally invasive image-based technologies and procedures used in diagnosis and treatment of diseases of the head, neck, and spine.

<span class="mw-page-title-main">Demetrius Klee Lopes</span> American neurosurgeon

Demetrius Klee Lopes is a cerebrovascular neurosurgeon specializing in neuroendovascular therapy. At Advocate Health, he serves as medical director of the cerebrovascular and neuroendovascular program and is co-director of their stroke program.

Thrombus perviousness is an imaging biomarker which is used to estimate clot permeability from CT imaging. It reflects the ability of artery-occluding thrombi to let fluid seep into and through them. The more pervious a thrombus, the more fluid it lets through. Thrombus perviousness can be measured using radiological imaging routinely performed in the clinical management of acute ischemic stroke: CT scans without intravenous contrast combined with CT scans after intravenously administered contrast fluid. Pervious thrombi may let more blood pass through to the ischemic brain tissue, and/or have a larger contact surface and histopathology more sensitive for thrombolytic medication. Thus, patients with pervious thrombi may have less brain tissue damage by stroke. The value of thrombus perviousness in acute ischemic stroke treatment is currently being researched.

Elad I. Levy is an American neurosurgeon, researcher, and innovator who played a major role in the development and testing of thrombectomy, which improved quality of life and survival of stroke patients. He has focused his career and research on developing evidence based medicine and literature showing the benefits of thrombectomy for the treatment of stroke. He is currently Professor of Neurosurgery and Radiology, and the L. Nelson Hopkins, MD Professor Endowed Chair of the Department of Neurosurgery at the State University of New York at Buffalo (SUNY).

<span class="mw-page-title-main">Arterial occlusion</span>

Arterial occlusion is a condition involving partial or complete blockage of blood flow through an artery. Arteries are blood vessels that carry oxygenated blood to body tissues. An occlusion of arteries disrupts oxygen and blood supply to tissues, leading to ischemia. Depending on the extent of ischemia, symptoms of arterial occlusion range from simple soreness and pain that can be relieved with rest, to a lack of sensation or paralysis that could require amputation.

References

  1. ↑ Saver JL, Goyal M, Bonafe A, et al. (June 11, 2015). "Stent-Retriever Thrombectomy after Intravenous t-PA vs. t-PA Alone in Stroke" (PDF). New England Journal of Medicine. 372 (24): 2285–2295. doi:10.1056/NEJMoa1415061. PMID   25882376.
  2. 1 2 3 4 5 6 7 Holland E (March 1, 2023). "This Revolutionary Stroke Treatment Will Save Millions of Lives. Eventually". The New York Times. Retrieved March 1, 2023.
  3. 1 2 Moore A (July 27, 2022). "Londoners several times more likely to get life-saving treatment". Health Service Journal. Retrieved September 28, 2022.
  4. ↑ Albers GW, Marks MP, Kemp S, et al. (February 22, 2018). "Thrombectomy for Stroke at 6 to 16 Hours with Selection by Perfusion Imaging". New England Journal of Medicine . 378 (8): 708–718. doi:10.1056/NEJMoa1713973. PMC   6590673 . PMID   29364767.
  5. ↑ Nogueira RG, Jadhav AP, Haussen DC, et al. (January 4, 2018). "Thrombectomy 6 to 24 Hours after Stroke with a Mismatch between Deficit and Infarct". New England Journal of Medicine . 378 (1): 11–21. doi: 10.1056/NEJMoa1706442 . PMID   29129157.
  6. ↑ Klail T, Piechowiak EI, Krug N, et al. (April 2024). "Endovascular revascularization of vertebrobasilar tandem occlusions in comparison to isolated basilar artery occlusions: A multi-center experience". Interventional Neuroradiology. doi:10.1177/15910199241240045. PMID   38576395.
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