Cerebral angiography is a critical diagnostic tool in neurology, serving as the gold standard for evaluating cerebrovascular stenosis, hemodynamics, aneurysms, and arteriovenous malformations. Compared to the traditional transfemoral approach, transradial cerebral angiography (TRA) offers advantages such as preserved patient privacy, immediate post-procedure mobility, shorter hospitalization, and fewer access-site complications. Consequently, TRA has gained increasing acceptance among patients and clinicians as the preferred vascular access . However, radial artery occlusion (RAO) remains a common complication post-TRA, with reported incidence rates varying widely (1%-33%). RAO is particularly concerning as the radial artery serves as a key access for both cardiac and neurovascular interventions; its occlusion limits future procedural options.Evidence from interventional cardiology suggests that intra-arterial heparin administration significantly reduces RAO risk.However, patients undergoing transradial cerebral angiography are predominantly those with cerebrovascular diseases, including acute ischemic stroke (AIS)-a population at potential risk for hemorrhagic transformation.Although the 2022 Chinese Expert Consensus on Neurointerventional Diagnosis and Treatment via Transradial Access recommends intra-sheath heparin injection to prevent RAO, this recommendation is largely extrapolated from coronary intervention data. While several studies indicate that low-dose heparin is safe in moderate-to-severe AIS patients without increasing intracranial hemorrhage risk , high-level evidence specific to neurointerventional procedures-particularly in AIS patients-remains lacking.This multicenter, double-blind, randomized controlled trial (RCT) aims to: Evaluate the efficacy of intra-arterial heparin in preventing RAO following TRA cerebral angiography.Assess the safety of heparin in AIS patients, with a focus on hemorrhagic complications. By addressing these questions, the study will provide evidence-based guidance to optimize TRA outcomes, balancing RAO prevention with bleeding risk in neurovascular interventions. Its findings hold significant clinical value for improving the safety and efficacy of transradial cerebral angiography.