Angiography
Angiography or tomography is called in medicine, the visualization of vessels, mostly blood vessels by means of diagnostic imaging procedures, such as X-ray or magnetic resonance imaging ( MRI). For this purpose, a contrast medium is often injected into the blood vessel. In the picture of the body recorded then the filled with the contrast medium vessel interior is emerging. The resulting image is called angiogram. Take the MRT and angiography without contrast agents are possible, which saves you the invasive puncture of the vessel. However, can not be answered satisfactorily with MRI angiography all questions.
Procedures and designations
Depending on the underlying imaging methods, various angiography can be distinguished:
- Digital subtraction angiography ( DSA)
- CT angiography (CTA )
- Magnetresonanzangiografie (MRA )
- Indocyanine green angiography of the retina
- The visualization of vessels with ultrasonography is strictly speaking also undergo angiography, but the term is not as common. Here bring the Doppler and duplex sonography additional information about blood flow.
In addition to arterial and venous ( venography ) blood vessels can also lymphatic vessels ( Lymphografie ) and not anatomical vessels such as vascular grafts or dialysis shunts are presented. The representation of the coronary arteries is called coronary angiography, angiography of a varicose vein by direct puncture varicography.
The short form angio for angiography is commonly used in the medical environment.
Indications
Angiography are mainly used to diagnose major diseases.
- Diseases of arteries: Atherosclerosis and its sequelae Vasoconstriction, for example, Coronary heart disease, carotid artery disease, peripheral arterial occlusive disease
- Acute vascular occlusion, such as during a heart attack
- Thrombosis
- Varicose veins
You also need occasionally undergo angiography to have clarity on the progress of key arteries for planning an operation.
Digital Substraktionsangiografie
Examination process
First, a catheter or an injection needle is introduced into the vascular system and positioned at or in front of the outlet of the blood vessel of interest. Before administration of the contrast agent, a normal image ( plain film ) can be made of the region examined. Then, the contrast agent injected through the catheter or needle into the vessel, of which recordings are made in quick succession. If these images are stored in digital form, it can be subtracted from the Angiografiebildern the empty receptacle. Disturbing image elements that are present on both images (eg, bone ) are thereby hidden, which facilitates the evaluation of the exposures. (Digital subtraction angiography ).
Whichever vessel has been punctured, a specific treatment ( for example, a pressure dressing ) is required.
Risks and benefits
The risks arise on the one hand from the puncture of blood vessels, especially when arteries are punctured. Hematoma, postoperative hemorrhage, aneurysms and fistulas may result. With the use of catheter and guide wire, it can also lead to vascular lesions removed the puncture site. By thrombus formation on the introduced into the vessel materials (eg the guide wire ) can cause embolisms with the result of vessel occlusion. On the other hand, the administration of the contrast agent cause allergic reactions, kidney damage ( Kontrastmittelnephropathie ) or - in the case of a pre-existing hyperthyroidism ( sneigung ) - an acute overactive thyroid ( hyperthyroidism) lead. Note also that in the case of X-ray imaging - especially at longer interventions - not low radiation exposure.
The angiography shows the contrast of the examined vessels with blood flow, and thus offers the combination of morphological information about the filling image and functional information about on and off behavior of the contrast as an expression of hemodynamics. The biggest and most unique advantage of angiography is that even procedures can be performed in the vessel during the investigation. Constricted vessels can be turned off distended ( angioplasty ) dissolved blood clots and aneurysms. Also shifted catheter can be aligned correctly again under certain circumstances.
Angiocardiography
In the heart angiocardiography the inner spaces ( courtyards, chambers ) can be represented in order to assess the size and function. Furthermore, large vessels, any existing shunts and also the coronary arteries that supply the heart, be accurately represented.
Access is either venous ( right heart catheterization ) or an artery ( cardiac catheterization ). The left ventricular catheter is inserted either through the femoral artery in the groin or the brachial artery in the cubital fossa, which is advanced into the left ventricle or the disposal of the coronary arteries ( coronary angiography ). The right heart catheter is introduced via the femoral vein in the groin or the brachial vein in the crook of the arm. After the catheter is inserted, a contrast agent is injected, the distribution can then be recorded with a Cinematographiefilm.
Some issues at the same time can also tissue samples are taken or current pulses are delivered to check the conduction system. In addition, therapeutic interventions can be made (eg, balloon dilation, stent system), especially in the coronary arteries.
Contraindications to catheterization are allergic to the contrast agent, hyperthyroidism, congestive heart failure and coagulation disorders.