Neurointervention as a booming field has been more and more widely used in recent years, but there are often some very detailed issues that are not paid attention to during the operation, which may not lead to serious complications in other interventions, but can lead to serious consequences during neurointervention. We (Shanghai Changhai Hospital) use a maintenance drip to prevent infarction, which is a tee connected to a pressurized fluid to maintain high pressure in the contrast tube to prevent blood from flowing back into the contrast tube. If blood flows back, when the guidewire or microcatheter is operated, it will trigger the defibrinization effect and form white flocculent on the guidewire. It is easy to dislodge and embolize the intracranial artery causing cerebral ischemia. When there is no guidewire in the contrast tube, the drip rate will be lowered to prevent excessive fluid input. When the guidewire or catheter is replaced and the tail of the Y-valve is to be opened, if the drip is not fast enough or the action is not skilled for too long, it can cause reflux. In this case, we prevent reflux by adjusting the drip rate at any time to eliminate one of the operational aspects that cause thrombosis. Eliminate air bubbles into the catheter, in the hand-push contrast syringe with contrast agent to the tee before, should turn the tee to the closed state, and then half turn the drip to connect the direction of the proposed syringe to flush the air bubbles from the tee interface and syringe nipple, after connecting the syringe first slightly loose hand so that the possible residual air bubbles are flushed into the syringe, and then connect the syringe with the catheter, playing the drug when the syringe tail is above (high) so that the possible presence of The air bubbles are left at the end of the syringe and are not pushed to the bottom when the contrast agent is injected. Sometimes there is a mistake of connecting the tee directly to the catheter and the proposed syringe port causing blood to return; sometimes no attention is paid to flush out the air bubbles at the interface; sometimes the syringe is pushed to the end and the gas is pushed into the catheter; sometimes the air bubbles enter the catheter first when the syringe is pushed at the nipple without the end of the syringe upwards, causing air embolism. A small experience I hope to throw in the towel, first show ugly pull. The first step of the femoral artery puncture is easy to make a mistake. 1, the femoral artery is on the medial side of the femoral head, the femoral artery usually crosses the midpoint of the inguinal ligament obliquely, puncture in the inguinal ligament under 2 to 3 cm, can avoid the formation of intraperitoneal hematoma, postoperative sheath extraction or compression bandage. 2, local anesthesia first play a 1 cm mound, then infiltrate the femoral artery on both sides and above, pay attention not to puncture the femoral artery, play anesthetic to draw back to sure that the tip of the needle is not in the blood vessel. If inadvertently penetrate into the vessel, withdraw the anesthesia needle and compress the vessel by hand until hemostasis. 3. When puncturing, the bevel of the needle tip faces upward and is 45° to the skin (30° for thin patients, up to 60° for fat ones), when the needle tip is close to the artery, the pulsation of the vessel can be felt, send the needle in smoothly, through the artery, remove the needle core, and slowly back off the needle to stop the needle tip is located in the arterial cavity, blood should be ejected forcefully! The guidewire can only be inserted. If the blood return is very weak and little, or the blood color is dark, the needle may be in the femoral vein or tight* artery wall, or may even be under the intima, never insert the guidewire and vascular sheath, otherwise it leads to femoral artery entrapment. We do have such complications in practice, so as a general principle, if the artery is not active enough to return blood, it is best to remove the needle, compress that artery for 5 minutes, and re-pierce or pierce the contralateral femoral artery, rather than risk lifting the femoral artery intima! In quite a few cases it is possible to penetrate only the anterior wall of the femoral artery: after the puncture needle is placed against the anterior wall of the femoral artery one can clearly feel the beating of the artery towards the palm of the hand and puncture it decisively, but only to a depth of 2-4 mm (estimated), i.e. the arterial blood is seen to eject. I prefer to use an elbow guidewire when puncturing, and the chance of the guidewire poking outside the arterial lumen is rare: the resistance of the elbow guidewire is high. The needle is slowly backed up to stop the tip of the needle in the arterial lumen, and blood should be ejected with force! …… blood should be ejected forcefully with a clear pulsatile ejection of blood. When the guidewire is placed, if the drip rate is not adjusted upward, reflux is likely to occur. Can reflux be reduced or prevented when the Y-valve knob is tightened immediately after the guidewire is placed and the guidewire is reintroduced? After withdrawing the guidewire from the major part of the contrast or performing other operations, when reintroducing the guidewire, wipe the guidewire with a gauze dipped in heparin water to lubricate the guidewire for smooth operation and to remove deposits on the guidewire and prevent thrombosis. Regardless of the location of the skin puncture point, the position of the arterial wall should be within 1 cm above and below the inguinal wall; if it is high, there is a risk of intraperitoneal hematoma; if it is low, it may enter the branches of the femoral artery, such as the deep femoral artery, and the guidewire cannot enter. It is easy to penetrate the anterior wall directly into the lumen in superficial arteries, but it may be easier to penetrate the whole layer and then retreat into the lumen in obese people with weak pulses. We still do not have 3D-DSA, and the angle of projection is still determined empirically. In a case of CA bifurcation aneurysm a few days ago, the conventional angle was not obvious, and it was difficult to determine a better angle and embolization without the help of 16-row CTA images. To eliminate air bubbles from entering the catheter my experience is that the head end of the syringe is pointed downward to allow any air bubbles to rise to the end of the syringe, and gentle tapping of the syringe often helps the air bubbles to rise to the end of the syringe. The syringe is then injected, the catheter is flushed with heparin saline, and the three-way switch is turned to the closed position mid-injection! This last point may seem small, but it is important! Turning the tee switch to the closed position mid-injection ensures that the heparin saline will completely fill the entire catheter, including its tip. In addition, whether injecting contrast or flushing, it is best to allow a little blood to return when the syringe is attached to the connector, creating a half-moon protrusion at the connector and a half-moon protrusion at the end of the syringe, which are placed together in the “half-moon-half-moon technique” to reduce the possibility of air getting between the syringe and the catheter. This reduces the possibility of air getting between the syringe and the catheter. The new angiographer will feel that there are many steps to remember, but with experience, these safety rules will become habitual and can be completed without thought. Remember: retained blood clots are the cerebral angiographer’s main enemy!