Angiographies are generally an invasive diagnostic procedure. This means that the skin barrier is broken in order to enter the inside of the body. The complications are nevertheless manageable.
The most frequent undesirable complications are related to the puncture. Since the contrast medium has to be injected into the blood vessels, a vessel is injured by a catheter, which is usually very thin. This involves greater risks with arterial vessels than with venous vessels, as the blood pressure in the artery is significantly higher.
If the bleeding is not stopped sufficiently after the procedure, bleeding will occur into the surrounding tissue of the injection site. In rare cases, aneurysms or fistulas can also develop in the vessel. Depending on the site of the operation, for example the heart, a slight feeling of tension may occur shortly after the examination.
During the examination itself, one normally does not feel much. Any part of the vessels and organs that the catheter passes through can theoretically be injured by the plastic. Thanks to the particularly soft and flexible material of the catheter, these risks have now been largely eliminated. The contrast medium can cause allergic reactions in some people. Depending on the type of contrast medium, problems with the thyroid gland or kidney may occur.
The task of contrast medium in angiography is to attract attention in the radiological image by a deviating absorption behaviour of the X-rays. This allows the region through which the contrast medium flows to be clearly distinguished from the rest of the soft tissue in the body. Contrast media containing iodine are used particularly frequently.
Substances such as iodine are also known as radiopaque. They absorb the radioactive rays to a high degree and thus form the contrast. They are contrasted with various newer substances.
These include saline solutions or even gaseous carbon dioxide. They are called X-ray negative because they are extremely permeable to the rays. They are mainly used for iodine intolerance. For MRI angiography, so-called “gadolinium chelates” are mainly used.
Angiography in connection with magnetic resonance imaging is also known as magnetic resonance angiography, or “MRA” for short. This produces a three-dimensional image in many layers and planes. There are several techniques, but unlike other angiographic examinations, it is not necessary to insert a catheter into the vessel.
The great advantage of magnetic resonance angiographies is that they largely do not require a contrast medium and thus do not require puncture of a vessel. The MRI, which measures the magnetization of all soft tissue, detects a high magnetization, especially with freshly inflowing blood. The fact that the remaining tissues stand still and the blood flow changes only in the vessels means that they can be displayed with a high level of signal.
In other procedures, a contrast medium containing gadolinium can also be used. In this case it is not necessary to use a long catheter. Even in very small amounts it enhances the vascular imaging enormously. A further advantage of MRI is also the lack of radiation exposure, which must always be taken into account when taking X-rays or CT images.