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Angiography | |
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ICD-9-CM | 88.40-88.68 |
MeSH | D000792 |
OPS-301 code | 3–60 |
Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is performed by injecting a radio-opaque contrast agent into the blood vessel and imaging using X-ray based techniques such as fluoroscopy.
The word itself comes from the Greek words ἀγγεῖον angeion 'vessel' and γράφειν graphein 'to write, record'. The film or image of the blood vessels is called an angiograph, or more commonly an angiogram. Though the word can describe both an arteriogram and a venogram, in everyday usage the terms angiogram and arteriogram are often used synonymously, whereas the term venogram is used more precisely. [1]
The term angiography has been applied to radionuclide angiography and newer vascular imaging techniques such as CO2 angiography, CT angiography and MR angiography. [2] The term isotope angiography has also been used, although this more correctly is referred to as isotope perfusion scanning.
The technique was first developed in 1927 by the Portuguese physician and neurologist Egas Moniz at the University of Lisbon to provide contrasted X-ray cerebral angiography in order to diagnose several kinds of nervous diseases, such as tumors, artery disease and arteriovenous malformations. Moniz is recognized as the pioneer in this field. [3] He performed the first cerebral angiogram in Lisbon in 1927, and Reynaldo dos Santos performed the first aortogram in the same city in 1929. In fact, many current angiography techniques were developed by the Portuguese at the University of Lisbon. For example, in 1932, Lopo de Carvalho performed the first pulmonary angiogram via venous puncture of the superior member. In 1948 the first cavogram was performed by Sousa Pereira. With the introduction of the Seldinger technique in 1953, the procedure became markedly safer as no sharp introductory devices needed to remain inside the vascular lumen. Radial access technique for angiography can be traced back to 1989, when Lucien Campeau first cannulated the radial artery to perform a coronary angiogram. [4]
Depending on the type of angiogram, access to the blood vessels is gained most commonly through the femoral artery, to look at the left side of the heart and at the arterial system; or the jugular or femoral vein, to look at the right side of the heart and at the venous system. Using a system of guide wires and catheters, a type of contrast agent (which shows up by absorbing the X-rays), is added to the blood to make it visible on the X-ray images.
The X-ray images taken may either be still, displayed on an image intensifier or film, or motion images. For all structures except the heart, the images are usually taken using a technique called digital subtraction angiography or DSA. Images in this case are usually taken at 2–3 frames per second, which allows the interventional radiologist to evaluate the flow of the blood through a vessel or vessels. This technique "subtracts" the bones and other organs so only the vessels filled with contrast agent can be seen. The heart images are taken at 15–30 frames per second, not using a subtraction technique. Because DSA requires the patient to remain motionless, it cannot be used on the heart. Both these techniques enable the interventional radiologist or cardiologist to see stenosis (blockages or narrowings) inside the vessel which may be inhibiting the flow of blood and causing pain.
After the procedure has been completed, if the femoral technique is applied, the site of arterial entry is either manually compressed, stapled shut, or sutured in order to prevent access-site complications. [5]
One of the most common angiograms performed is to visualize the coronary arteries. A long, thin, flexible tube called a catheter is used to administer the X-ray contrast agent at the desired area to be visualized. The catheter is threaded into an artery in the forearm, and the tip is advanced through the arterial system into the major coronary artery. X-ray images of the transient radiocontrast distribution within the blood flowing inside the coronary arteries allows visualization of the size of the artery openings. The presence or absence of atherosclerosis or atheroma within the walls of the arteries cannot be clearly determined.
Coronary angiography can visualize coronary artery stenosis, or narrowing of the blood vessel. The degree of stenosis can be determined by comparing the width of the lumen of narrowed segments of blood vessel with wider segments of adjacent vessel. [5]
Cerebral angiography provides images of blood vessels in and around the brain to detect abnormalities, including arteriovenous malformations and aneurysms. [6] One common cerebral angiographic procedure is neuro-vascular digital subtraction angiography. [7] [8]
Pulmonary angiography is used to visualise the anatomy of pulmonary vessels.
Angiography is also commonly performed to identify vessels narrowing in patients with leg claudication or cramps, caused by reduced blood flow down the legs and to the feet; in patients with renal stenosis (which commonly causes high blood pressure) and can be used in the head to find and repair stroke. These are all done routinely through the femoral artery, but can also be performed through the brachial or axillary (arm) artery. Any stenoses found may be treated by the use of balloon angioplasty, stenting, or atherectomy.
Fluorescein angiography is a medical procedure in which a fluorescent dye is injected into the bloodstream. The dye highlights the blood vessels in the back of the eye so they can be photographed. This test is often used to manage eye disorders. [9]
Optical coherence tomography (OCT) is a technology using near-infrared light to image the eye, in particular penetrate the retina to view the micro-structure behind the retinal surface. Ocular OCT angiography (OCTA) is a method leveraging OCT technology to assess the vascular health of the retina. [10]
Microangiography is commonly used to visualize tiny blood vessels.
Post mortem CT angiography for medicolegal cases is a method initially developed by the Virtopsy group. Originating from that project, both watery [11] and oily [12] solutions have been evaluated.
While oily solutions [12] require special deposition equipment to collect waste water, watery [11] solutions seem to be regarded as less problematic. Watery solutions also were documented to enhance post mortem CT tissue differentiation whereas oily solutions were not. Conversely, oily solutions seem to only minimally disturb ensuing toxicological analysis, while watery solutions may significantly impede toxicological analysis, thus requiring blood sample preservation before post mortem CT angiography. [13]
Angiography is a relatively safe procedure. But it does have some minor and very few major complications. After an angiogram, a sudden shock can cause a little pain at the surgery area, but heart attacks and strokes usually don't occur, as they may in bypass surgery.
Major complications in cerebral angiography such as in digital subtraction angiography or contrast MRI are also rare but include stroke, an allergic reaction to the anaesthetic other medication or the contrast medium, blockage or damage to one of the access veins in the leg, pseudoaneurysm at the puncture site; or thrombosis and embolism formation. Bleeding or bruising at the site where the contrast is injected are minor complications, delayed bleeding can also occur but is rare. [14]
The contrast medium that is used usually produces a sensation of warmth lasting only a few seconds, but may be felt in a greater degree in the area of injection. If the patient is allergic to the contrast medium, much more serious side effects are inevitable; however, with new contrast agents the risk of a severe reaction is less than one in 80,000 examinations. Additionally, damage to blood vessels can occur at the site of puncture/injection, and anywhere along the vessel during passage of the catheter. If digital subtraction angiography is used instead, the risks are considerably reduced because the catheter does not need to be passed as far into the blood vessels; thus lessening the chances of damage or blockage.
Antibiotic prophylaxis may be given in those procedures that are not clean, or clean procedures that results in generation of infarcted or necrotic tissues such as embolisation. Routine diagnostic angiography is often considered a clean procedure. Prophylaxis is also given to prevent infection from infected space into blood stream. [15]
There are six risk factors causing thrombosis after arterial puncture: low blood pressure, small arterial diameter, multiple puncture tries, long duration of cannulation, administration of vasopressor/inotropic agents, [16] and the usage of catheters with side holes. [17]
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. A deflated balloon attached to a catheter is passed over a guide-wire into the narrowed vessel and then inflated to a fixed size. The balloon forces expansion of the blood vessel and the surrounding muscular wall, allowing an improved blood flow. A stent may be inserted at the time of ballooning to ensure the vessel remains open, and the balloon is then deflated and withdrawn. Angioplasty has come to include all manner of vascular interventions that are typically performed percutaneously.
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.
A coronary catheterization is a minimally invasive procedure to access the coronary circulation and blood filled chambers of the heart using a catheter. It is performed for both diagnostic and interventional (treatment) purposes.
Intravascular ultrasound (IVUS) or intravascular echocardiography is a medical imaging methodology using a specially designed catheter with a miniaturized ultrasound probe attached to the distal end of the catheter. The proximal end of the catheter is attached to computerized ultrasound equipment. It allows the application of ultrasound technology, such as piezoelectric transducer or CMUT, to see from inside blood vessels out through the surrounding blood column, visualizing the endothelium of blood vessels.
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.
Cardiac catheterization is the insertion of a catheter into a chamber or vessel of the heart. This is done both for diagnostic and interventional purposes.
Embolization refers to the passage and lodging of an embolus within the bloodstream. It may be of natural origin (pathological), in which sense it is also called embolism, for example a pulmonary embolism; or it may be artificially induced (therapeutic), as a hemostatic treatment for bleeding or as a treatment for some types of cancer by deliberately blocking blood vessels to starve the tumor cells.
Pulmonary angiography is a medical fluoroscopic procedure used to visualize the pulmonary arteries and much less frequently, the pulmonary veins. It is a minimally invasive procedure performed most frequently by an interventional radiologist or interventional cardiologist to visualise the arteries of the lungs.
Transcatheter arterial chemoembolization (TACE) is a minimally invasive procedure performed in interventional radiology to restrict a tumor's blood supply. Small embolic particles coated with chemotherapeutic drugs are injected selectively through a catheter into an artery directly supplying the tumor. These particles both block the blood supply and induce cytotoxicity, attacking the tumor in several ways.
Magnetic resonance angiography (MRA) is a group of techniques based on magnetic resonance imaging (MRI) to image blood vessels. Magnetic resonance angiography is used to generate images of arteries in order to evaluate them for stenosis, occlusions, aneurysms or other abnormalities. MRA is often used to evaluate the arteries of the neck and brain, the thoracic and abdominal aorta, the renal arteries, and the legs.
Digital subtraction angiography (DSA) is a fluoroscopy technique used in interventional radiology to clearly visualize blood vessels in a bony or dense soft tissue environment. Images are produced using contrast medium by subtracting a "pre-contrast image" or mask from subsequent images, once the contrast medium has been introduced into a structure. Hence the term "digital subtraction angiography. Subtraction angiography was first described in 1935 and in English sources in 1962 as a manual technique. Digital technology made DSA practical starting in the 1970s.
Computed tomography angiography is a computed tomography technique used for angiography—the visualization of arteries and veins—throughout the human body. Using contrast injected into the blood vessels, images are created to look for blockages, aneurysms, dissections, and stenosis. CTA can be used to visualize the vessels of the heart, the aorta and other large blood vessels, the lungs, the kidneys, the head and neck, and the arms and legs. CTA can also be used to localise arterial or venous bleed of the gastrointestinal system.
Fractional flow reserve (FFR) is a diagnostic technique used in coronary catheterization. FFR measures pressure differences across a coronary artery stenosis to determine the likelihood that the stenosis impedes oxygen delivery to the heart muscle.
A coronary stent is a tube-shaped device placed in the coronary arteries that supply blood to the heart, to keep the arteries open in patients suffering from coronary heart disease. The vast majority of stents used in modern interventional cardiology are drug-eluting stents (DES) It is used in a medical procedure called percutaneous coronary intervention (PCI). Coronary stents are divided into two broad types - drug-eluting and bare metal stents, as of 2023 drug-eluting stents were used in more than 90% of all PCI procedures. Stents reduce angina and have been shown to improve survival and decrease adverse events after a patient has suffered a heart attack - medically termed an acute myocardial infarction.
Carotid ultrasonography is an ultrasound-based diagnostic imaging technique to evaluate structural details of the carotid arteries. Carotid ultrasound is used to diagnose carotid artery stenosis (CAS) and can assess atherosclerotic plaque morphology and characteristics. Carotid duplex and contrast-enhanced ultrasound are two of the most common imaging techniques used to evaluate carotid artery disease.
Cardiac imaging refers to minimally invasive imaging of the heart using ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), or nuclear medicine (NM) imaging with PET or SPECT. These cardiac techniques are otherwise referred to as echocardiography, Cardiac MRI, Cardiac CT, Cardiac PET and Cardiac SPECT including myocardial perfusion imaging.
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.
Transarterial bland embolization is a catheter-based tumor treatment of the liver. In this procedure, a variety of embolizing agents can be delivered through the tumor’s feeding artery in order to completely occlude the tumor’s blood supply. The anti-tumor effects are solely based on tumor ischemia and infarction of tumor tissue, as no chemotherapeutic agents are administered. The rationale for the use of bland embolization for hepatocellular carcinoma(HCC) and/or other hyper-vascular tumors is based on the fact that normal liver receives a dual blood supply from the hepatic artery (25%) and the portal vein (75%). As the tumor grows, it becomes increasingly dependent on the hepatic artery for blood supply. Once a tumor nodule reaches a diameter of 2 cm or more, most of the blood supply is derived from the hepatic artery. Therefore, bland embolization and transarterial chemoembolization (TACE) consist of the selective angiographic occlusion of the tumor arterial blood supply with a variety of embolizing agents, with or without the precedence of local chemotherapy infusion. The occlusion by embolic particles results in tumor hypoxia and necrosis, without affecting the normal hepatic parenchyma.
Carbon dioxide angiography is a diagnostic radiographic technique in which a carbon dioxide (CO2) based contrast medium is used - unlike traditional angiography where the contrast medium normally used is iodine based – to see and study the body vessels. Since CO2 is a non-radio-opaque contrast medium, angiographic procedures need to be performed in subtraction angiography (DSA).
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.
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