Angiography is a radiological procedure for imaging the vessels of the human organism. During an angiographic examination, the venous and arterial blood vessels, as well as the lymphatic vessels, can be imaged using X-rays, magnetic resonance imaging or computed tomography.
What is angiography?
Angiography is the imaging of vessels, usually blood vessels using diagnostic imaging techniques, such as X-ray or magnetic resonance imaging (MRI). For this purpose, a contrast agent is often injected into the blood vessel. Angiography is a minimally invasive imaging procedure used to visualize human blood vessels and their changes (including narrowing) using catheters and/or contrast agents. Standard angiography is performed as so-called digital subtraction angiography. In addition, CT angiography, magnetic resonance angiography or indocyanine angiography are available for imaging the ocular fundus. As part of the various angiographic examination procedures, the venous and arterial blood vessels (phlebography), lymphatic vessels (lymphography), coronary vessels (coronary angiography), varicose veins (varicography), and vascular prostheses can be imaged.
Function, effect, and goals
To image the vessels, conventional angiography uses an X-ray tube with an image intensifier, usually placed in a C-arm arrangement. During angiography, the C-arm is guided on or around the patient to ensure imaging of the vessels from different perspectives. Prior to the examination, the patient is administered a local anesthetic so that a puncture needle can then be inserted painlessly into the artery or vein to be examined. A flexible, narrow guide wire with a soft tip is first inserted via the puncture needle, and then a catheter is placed in the vessel at the site to be examined with the help of the wire. A contrast agent injected through the catheter is used to visualize and assess the blood vessel. During the injection of the contrast medium, electronic images of the region to be assessed are taken with the X-ray tube at short intervals, which are then post-processed with the computer so that only the blood vessels of interest are shown (digital subtraction angiography). In contrast, in a CT angiography, the contrast agent is not injected directly into the vascular area to be examined, but into the arm vein. Angiography is a radiological procedure for imaging the vessels of the human organism. MR angiography provides three-dimensional images and can be performed with or without contrast medium. One advantage over conventional radiographic vascular imaging is that it does not require catheters. Angiography serves as an important tool for confirming the diagnosis of vascular diseases. Angiography is used for changes in arterial vessels such as arteriosclerosis and its secondary diseases (stenoses, peripheral arterial occlusive disease), acute occlusions (including myocardial infarction), aneurysms (vascular outpouching), malformations and injuries to vessels. Thromboses and varicose veins are typical changes in the venous vessels and can also be visualized angiographically. In addition, angiography can be performed prior to surgical interventions in peripheral vascular occlusive diseases, especially in cases of severely restricted walking distance (less than 200 meters), in cases of pronounced stenosis of the vessels supplying the brain, or to image the vessels of the organ to be operated on (including the liver). In addition, angiography can be used to exclude or detect renal artery stenosis (narrowing of the renal artery) in uncontrollable hypertension (high blood pressure).
Risks and hazards
Because angiography is a minimally invasive procedure, complications are generally not expected if performed properly. Following the examination, in rare cases, a hematoma may manifest at the puncture site. Impairments of the vessel walls (including aneurysm) also occur very rarely. Extremely rarely, in case of pronounced changes and/or calcifications in combination with stenoses, blood clots or occlusions and injuries of the vessels by the catheter or guide wire can be observed.In addition, if sensitivity to iodine has not been determined in advance, sneezing, pruritus (itching), skin rash or nausea and, in the worst case, severe reactions of the cardiovascular system (anaphylactic shock) may occur as a reaction to the contrast medium. Furthermore, angiography should not be used in the presence of a hemorrhagic diathesis (increased bleeding tendency) or generalized inflammation (including sepsis). While angiography with iodine-containing contrast media is contraindicated in cases of pronounced hypersensitivity due to the increased risk of anaphylactic shock, contrast media reactions of mild severity can be counteracted with medication to ensure angiography without side effects. In the case of thyroid dysfunction, the metabolic status of the organ should be checked prior to angiographic examination to prevent derailment. If renal dysfunction with elevated creatinine is present, alternative examination procedures such as Doppler ultrasonography or magnetic resonance imaging should be weighed against angiography to reduce the risk of additional functional impairment (contrast nephropathy).
