I. Complications due to puncture and cannulation 1. Hematoma at the puncture site: due to repeated puncture, improper compression hemostasis or coagulation dysfunction, etc. Generally, the sheath should be removed only when the KPTT is less than two times the basal value. Small hematomas may resorb on their own. If a large hematoma is caused by local moist hot compresses, and if it causes impaired blood circulation, such as obstruction of venous return or loss of arterial pulsation in the distal limb, immediate hematoma removal should be performed. 2. Arterial and venous spasm at the puncture site: seen in multiple punctures and prolonged intubation, especially in pediatric patients. It is characterized by local pain and edema, which may lead to thrombosis if not treated in time. In mild cases, local hot compress, local seal with procaine and elevation of the affected limb can be used; in severe cases, 30mg-60mg of poppy bases hydrochloride can be injected intravenously every 4-6 hours, or 15mg can be dissolved in 10ml of saline and slowly pushed into the artery. Ineffective patients should be given systemic heparinization within 1 hour, continuous medication for a week. 3, intracranial vasospasm: vertebral artery spasm is the most dangerous, can completely block the vertebral artery blood flow, causing acute undersupply of blood to the vertebral basilar artery, the patient is unconscious, and even sudden death. Prevention is important, such as the head end of the internal carotid artery angiography catheter should not exceed the level of the second cervical vertebra, and the head end of the vertebral artery angiography catheter should not exceed the level of the sixth cervical vertebra, and the residence time of the catheter in the vertebral artery should be minimized. If this occurs, the catheter should be removed quickly and allowed to resolve on its own. In severe cases, a microcatheter can be used to inject poppine (300 mg + 100 ml N.S., dripped within 1 hour) intra-arterially at the site of spasm, and nimodipine can be given continuously intravenously, while systemic heparinization is performed to prevent secondary thrombosis. 4. Pseudoaneurysm and arteriovenous fistula: The former is manifested by a limited pulsatile mass at the puncture site, while the latter can be detected in addition to the pulsatile mass and a vascular murmur can be heard. Early surgery should be performed to remove the pseudoaneurysm, and arteriovenous fistulae should be repaired and sutured to the arterial and venous walls. 5, catheter fracture in the artery, atherosclerotic plaque off embolism, thrombosis: if cause circulatory disorders, should be dealt with in a timely manner. The method of intra-arterial thrombosis: under the guidance of micro-guide wire, send the micro-catheter into the thrombus or as close as possible to the occluded cerebral artery segment, and inject the thrombolytic agent through the micro-catheter (hand-push or micro-pump); commonly use urokinase 500,000u added to 50ml of saline and input within 1 hour, the maximum dose is 900,000u ~ 1.5 millionu; or use recombinant streptokinase 150,000u ~ 250,000u, dilute and input within 1 hour, also t-PA (20mg+50ml N.S., 5-10mg/hr) can be used. If necessary, surgery should be performed to remove foreign bodies and blood clots. Complications due to contrast agent 1. Allergy to contrast agent: in mild cases, no treatment is needed; in severe cases, shock, convulsions, laryngeal edema, bronchospasm, pulmonary edema, etc. For those with a history of allergy, intravenous dexamethasone 5-10 mg can be injected before surgery, and resuscitation equipment and drugs are equipped. 2. Excessive amount or high concentration of contrast agent can lead to acute renal failure, seizures and cerebral edema, etc. Therefore, the total amount of contrast agent within 2 hours should not exceed 3.5ml/Kg; non-ionic water-soluble contrast agent should also be less than 5.0ml/Kg. Once it occurs, immediate resuscitation should be performed, such as intravascular flushing with saline, intravenous dexamethasone and tachypnea, reduction of intracranial pressure in cases of cranial hypertension, oxygenation and antiepileptic treatment, etc. The contrast agent used for fluoroscopic hand-pushing should be appropriately diluted, and the amount of contrast agent can be reduced. 3, neurological complications 4, epilepsy: often grand mal seizures. The imaging should be stopped immediately and antiepileptic drugs should be given intravenously. 5.Temporary motor and sensory impairment, corneal regurgitation, unconsciousness, one-sided actinic nerve palsy and contralateral hemiparesis, transient black haze and visual field defects, etc.: Once the above symptoms appear, the tube should be immediately removed, and oxygen, dehydration, intravenous drip of low molecular dextran and salvia solution should be given. 6, intracranial aneurysm or arteriovenous malformation rupture bleeding: patients with heparinization should immediately neutralize heparin, apply hemostatic agents and 20% mannitol to lower cranial pressure. Comatose patients should be immediately tracheally intubated and oxygenated. Review the cranial CT immediately and perform emergency craniotomy if necessary.