Drugs and equipment for cardiovascular angiography

Selective cardiovascular angiography requires appropriate contrast media and rapid continuous X-ray photography equipment, as well as appropriate cardiac catheters and pressurized syringes for angiography.

Contrast agents are currently mainly used in clinical practice: ionic contrast agents such as 60% to 76% diatrizoate meglumine, non-ionic contrast agents such as Euvitex, iohexol, Onipex, etc., as well as low-osmolar ionic contrast agents contrast agent. Children mainly use non-ionic contrast agents. The dosage is: 1~1.5ml/kg each time for children, the total dose shall not exceed 8~10ml/kg; 50~60ml each time for adults, the total dose shall not exceed 200ml. If an iodine allergy test is required before using ionic contrast agents, 1ml of 30% meglumine diatrizoate can be injected intravenously and observed for 20 minutes before use until there is no reaction. If you are allergic to meglumine diatrizoate, non-ionic contrast agent can be used. It may also cause some minor reactions in a small number of patients, such as nausea, vomiting, skin itching and rash. Therefore, patients with a history of iodine allergy should also consider emergency in advance. Treatment measures include corticosteroids and antihistamines before imaging. Non-ionic contrast agents have little risk of reaction and produce better images, but they are more expensive than ionic contrast agents.

The X-ray machine used for cardiovascular angiography needs to output a large amount of X-rays in a short period of time to shorten the exposure time, facilitate rapid continuous photography and improve image clarity, so it requires a large capacity of more than 50mA. The X-ray tube power is above 50kW. If two-way simultaneous photography is required, an X-ray machine of more than 1000kW or two X-ray machines of more than 500kW are required for simultaneous photography.

Fast photography requires a fast film changer to change films in conjunction with continuous exposure. Generally, a fast film changer can take up to 6 films per second, and the two front and side film changers can be linked simultaneously. Using a fluorescence image intensification device coupled with X-ray cinematography, 24 to 80 frames of images per second can be taken. The entire imaging process can be monitored on the TV system. When the film is shown, the flow of contrast agent in the heart, blood vessels, and various parts of the heart's great vessels can be monitored. Dynamic observation of the structure. At the same time, the imaging process can also be recorded on tape.

When taking photos, you can choose frontal, lateral or left or right oblique views as needed, and in recent years, axial angle projection is used. The contrast-enhanced area can be displayed with better results.

Digital subtraction angiography is a comprehensive image enhancement - television system data collection and computer processing to generate images, which can significantly reduce the concentration and dose of contrast agent, achieve excellent diagnostic results, thereby reducing or even avoiding high concentrations , the side effects of high-dose contrast agent injection, especially suitable for cases with reduced renal function. Mainly used for large blood vessel and peripheral angiography.

The main cardiac catheters used for angiography include pig tail catheters, side hole angiography catheters, end-side hole angiography catheters, floating balloon angiography catheters and coronary angiography catheters. F5 and F6 catheters are commonly used in children.

When the contrast agent is injected into the large blood vessel cavity of the heart through the cardiac catheter, it needs to form a ball in a pellet-like manner and quickly enter the blood from the front end of the cardiac catheter in order to achieve the highest concentration and clear visualization in this part, so the injection must And for fast. Since the contrast agent has a certain viscosity and the catheter lumen has a certain resistance, a high-pressure syringe must be used to achieve rapid injection. Generally, a dose of the drug is injected in about 1.5 seconds. After a certain amount of contrast agent is injected, the rapid injection button on the syringe is triggered. Exposure triggering device for photography or cinematography to start photography. If injection is required at a certain time during the cardiac cycle, a certain waveform of the patient's electrocardiogram must be used as a signal to trigger the syringe to start.