As vascular experts, interventional radiologists treat atherosclerosis, "hardening of the arteries," throughout the body.
Atherosclerosis, specifically in the carotid artery in the neck, can lead to ischemic stroke in some patients. Plaque in the carotid artery may result in a stroke by either decreasing blood flow to the brain or by breaking loose and floating into a smaller vessel, depriving a portion of the brain from blood flow.
In patients at high risk of having a stroke, the narrowed section of artery may be re-opened by an interventional radiologist through angioplasty and reinforced with a stent, thereby preventing the stroke from occurring. Vascular stents are typically made of woven, laser-cut or welded metal that permits the device to be compressed onto a catheter and delivered directly into the hardened artery. In addition to diagnosing and treating those at risk for stroke, interventional radiologists use their expertise in imaging, angioplasty and stenting to treat those having an acute stroke.
Patients can also take action to prevent strokes by:
- Stopping smoking
- Controlling high blood pressure
- Lowering cholesterol levels
- Maintaining healthy weight
- Utilizing appropriate medications like aspirin and prescription drugs like anticoagulants
- Treating carotid artery disease
- Treating unruptured cerebral aneurysm or arteriovenous malformations
Interventional radiologists are a critical part of the stroke team in hospitals and are actively involved in creating more stroke teams across the country. Stroke teams generally consist of emergency room physicians, neurologists and interventional radiologists.
For those having a stroke, it must first be determined which kind of a stroke the patient is having so the proper treatment can be given. The interventional radiologist interprets the non-contrast CT imaging to determine if acute stroke patients are candidates for clot-busting drugs. CT is quick, inexpensive and readily available.
If the stroke is determined to be ischemic (due to a blood clot), the interventional radiologist will assess what caused the clot, such as a clogged carotid or other artery, and can correct the underlying problem to prevent future strokes from occurring.
Treatment to Dissolve Blood Clots
If the stroke is due to a blood clot, a clot-busting drug, tPA (tissue plasminogen activator) can be given intravenously to break up or reduce the size of blood clots to the brain. This technique must be performed within three hours from the onset of symptoms.
When therapy cannot be initiated within three hours or when treatment with tPA during the first three hours is not sufficient to dissolve the blood clot, interventional radiologists who specialize in neurological procedures can provide intra-arterial thrombolysis treatment.
Using X-ray guidance, an interventional radiologist will insert a catheter through a nick in the skin at the groin and advance it through the femoral artery in the leg all they way to the tiny arteries in the brain where the interventional radiologist will place the clot-busting drug directly on the clot or break up the clot mechanically.
When given locally this way, the tPA can be administered up to six hours after the onset of stroke symptoms. In many cases, the ambulance drivers will take a stroke victim past the three-hour window directly to the interventional radiology suite for assessment for this direct thrombolytic therapy. Often, a significantly disabled stroke patient who receives this treatment can return to normal life with minimal or no aftereffects from the stroke.
Treatments to Open Narrowed Carotid Arteries
If a stroke is the result of narrowing of the carotid arteries, follow-up treatment may be needed to open the narrowing and prevent another stroke. These treatments also are used to prevent stroke in people who have been diagnosed with significant blockage in the carotid artery, usually as a result of atherosclerosis.
- Carotid endarterectomy surgery. The most common treatment for narrowing of the carotid arteries involves a surgeon making an incision in the neck, opening the carotid artery and scraping out the built-up plaque.
- Carotid artery angioplasty and stenting. More recently, an interventional radiology procedure called carotid artery angioplasty and stenting that does not require open surgery has been developed. In this technique, a catheter is inserted through a nick in the skin, usually in the groin, and threaded under X-ray guidance to the carotid artery. A balloon is inflated to compress the plaque against the wall of the blood vessel and open up the artery. Usually, a tiny wire cylinder called a stent is inserted and acts like a scaffold to keep the artery open. There are a number of potential advantages to carotid artery angioplasty and stenting, primarily because it is less invasive than surgery.
Interventional Radiology Advantages
- Can be performed with local anesthesia. Avoidance of general anesthesia may decrease some of the postoperative complications of surgery.
- Avoids surgical complications such as cranial nerve injury, hematoma (bruising) and wound infection.
- Takes less time.
- Can treat narrowed arteries that are hard to reach or difficult to treat with surgery.
- Is less painful for patients and may reduce hospital stays and shorten recovery times.
- May be safer for patients who are at high risk for surgery.
Treatments for Ruptured Blood Vessels in the Brain
When a stroke is caused by bleeding into the brain (hemorrhagic stroke), the treatment is different from that used to treat strokes caused by blood clots.
The major causes of hemorrhagic stroke are:
- A ruptured aneurysm. An aneurysm develops when a weakened area of a blood vessel fills with blood and bulges or balloons out. Sometimes aneurysms cause headaches or other symptoms, but unfortunately, most patients do not realize that they have an aneurysm until it ruptures. Aneurysms can usually be diagnosed before they rupture with computed tomography angiography and magnetic resonance angiography.
- A ruptured arteriovenous malformation. AVMs are abnormal tangles of blood vessels in the brain that can rupture and cause life-threatening bleeding.
Treatments for Hemorrhagic Stroke
Interventional neuroradiologists can also treat ruptured aneurysms inside the brain causing hemorrhage into the subarachnoid space, which can cause stroke or death. One recent study in the Lancet showed that the minimally invasive interventional technique substantially reduced the relative and absolute risk of subsequent severe disability or death compared to surgical repair in those patients who were candidates for both procedures.
During the embolization technique, an interventional neuroradiologist inserts a catheter through a nick in the skin of the groin and advances it to the site of the ruptured blood vessel. An embolic agent (a substance that clots or closes off the bleeding blood vessel) is injected under X-ray guidance. Most commonly, tiny metal coils are used to embolize and block the abnormal blood vessel or aneurysm. The catheter is withdrawn and the coils remain to provide the occlusion. The same technique can be used to treat aneurysms and AVMs before they rupture. Surgery had been the primary treatment available until the platinum coil device was approved by the FDA in 1995.
Reprinted with permission of the Society of Interventional Radiology © 2004, www.SIRweb.org. All rights reserved.