Evolution of the method and basic principles
The first vascular contrast study was performed by Dos Santos (Dos Santos) in 1929; however, a true revolution occurred in 1953 with the introduction of the Seldinger technique (Seldinger technique). In the 1960s and 1970s, the method was used exclusively for diagnostic purposes. Today, thanks to the widespread availability of CT angiography, the need for purely diagnostic invasive procedures has practically disappeared. Modern catheter angiography is a stage of planned endovascular treatment performed in specialized hybrid operating rooms.
The basic principles remain unchanged: strict sterility, safe arterial access, and the use of the «catheter — contrast — X-ray radiation» triad. Meanwhile, bulky image intensifiers have been replaced by digital flat panel detectors (digital flat panel detectors). They provide high resolution, allow for complex image post-processing, and significantly reduce radiation exposure to the patient and staff.
Medication preparation of the patient
Patient safety is ensured through thorough pre-angiography screening. It is recommended to use specialized checklists (e.g., from the Cardiovascular and Interventional Radiological Society of Europe — CIRSE). Particular attention is paid to the medication history and renal function assessment:
- Anticoagulants and antiplatelet agents: discontinuation of aspirin and clopidogrel is not required in most cases. Vitamin K antagonists are discontinued 5–7 days before the intervention (strictly after consulting the attending physician).
- Renal function: estimated glomerular filtration rate (eGFR) must be calculated. If the value drops below 30 mL/min/1.73 m², the patient requires prehydration.
- Metformin: must be discontinued.
- Allergy history: if a risk of reactions to the X-ray contrast agent is identified, premedication is prescribed (antihistamines and steroids). In cases of a history of severe allergic reactions, the procedure is canceled or replaced with CO2 angiography.
Arterial puncture technique
Access to the artery requires conditions fully comparable to those of a surgical operating room. The classic Seldinger technique has undergone important modifications that have made it safer. First, there has been a widespread abandonment of double-wall vessel puncture in favor of puncturing exclusively the anterior wall (single wall arterial puncture technique). Second, ultrasound (US) guidance for every puncture has become the gold standard.
US guidance (US guidance) dramatically reduces the number of failed access attempts and allows for clear visualization of calcified plaques. By bypassing areas of calcification, the surgeon minimizes the risks of massive bleeding from the puncture site and distal embolization by fragments of the disrupted plaque.
Instruments and critical safety rules
Access utilizes a sharp metal needle with a bevel and a simple metal guidewire (preferably Teflon-coated with a J-tip). During insertion, the needle bevel must face strictly anteriorly.
There is a critically important rule, the violation of which leads to severe iatrogenic complications: it is strictly forbidden to use hydrophilic-coated guidewires (glide-wires) in combination with beveled needles. If a physician attempts to pull such a guidewire back through the needle, the sharp edge will inevitably shear the outer polyurethane coating. This will lead to the detachment of a fragment of the guidewire coating and its distal embolization in the vascular bed.
Briefly: answers to topical questions
Which drugs must be discontinued before elective angiography?
Before elective angiography, metformin must be discontinued. Vitamin K antagonists must also be stopped 5–7 days before the procedure, but this must be done strictly after consulting the attending physician. Most antiplatelet agents (aspirin, clopidogrel) do not need to be stopped. Renal function monitoring and history taking are mandatory.
In what cases is standard X-ray contrast replaced with carbon dioxide (CO2 angiography) during angiography?
Standard iodine-containing X-ray contrast is replaced with CO2 angiography in cases of iodine hypersensitivity or renal impairment. If severe allergic reactions are present, the procedure should be abandoned or CO2 angiography should be used.
What phases of contrast circulation are distinguished during serial angiography?
Serial angiography distinguishes three main phases of contrast circulation, which provide a complete picture of the blood supply to organs, tissues, and bones.
- Arterial phase — visualization of the arterial bed.
- Capillary phase — phase of microcirculation in the area of interest.
- Venous phase — visualization of venous outflow.
What instruments are included in the basic kit for vessel catheterization using the Seldinger technique?
The basic kit for vessel catheterization using the Seldinger technique includes a sharp metal puncture needle with a bevel, a Teflon-coated metal guidewire, preferably with a J-tip, and a catheter. If necessary, the tract is sequentially dilated with dilators before catheter insertion.
What are the absolute contraindications to the intravascular administration of iodine-containing contrast agents?
In the cited sources, contrast media anaphylaxis is indicated as a major absolute contraindication to cerebral angiography if the reaction is documented and cannot be medically managed. Severe renal failure is considered a relative contraindication to cerebral angiography.
The hydrophilic guidewire rule: "A beveled needle will shear a slippery wire" — a reminder of the strict ban on using glide-wires with standard puncture needles.
Class and exam questions
Why is catheter angiography no longer used solely for diagnostics?
With the development of CT and CT angiography, it has become possible to obtain accurate data on the vascular bed non-invasively. Catheter methodology is now used primarily as the first stage of endovascular treatment.
How has the Seldinger technique been modified in modern conditions?
Physicians have shifted from puncturing both arterial walls to puncturing only the anterior wall. In addition, ultrasound guidance for every puncture has become a mandatory standard.
What should be done if a patient has a severe allergy to X-ray contrast media?
In such situations, the standard procedure is abandoned. An alternative can be CO2 angiography, which uses carbon dioxide.
What else to study on this topic
- Pre-angiography screening and the use of CIRSE checklists
- Prehydration protocols in reduced glomerular filtration rate
- CO2 angiography: principles of the method and limitations
- US semiotics of arteries and assessment of calcified plaques during access
- Differences between digital flat panel detectors and image intensifiers
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