Transulnar Access in Patients With Ipsilateral Radial Artery Occlusion Undergoing Coronary Angiography or Angioplasty

Inclusion Criteria Participants must meet all of the following criteria to be eligible: * Adults aged 18 years or older * Documented radial artery occlusion in the upper limb intended for vascular access, confirmed by ultrasound or angiography * Scheduled to undergo elective coronary angiography and/or angioplasty * Transulnar arterial access on the same side as the occluded radial artery is selected by the treating physician * Contralateral radial artery access is not feasible or is clinically undesirable, including for reasons such as: * documented occlusion or severe disease of the contralateral radial artery * unfavorable anatomy or prior failed access * strategic preservation of the contralateral radial artery for future surgical or dialysis needs * Adequate ulnar artery flow and anatomy for access, as assessed by pre-procedural ultrasound * Able and willing to provide written informed consent Exclusion Criteria Participants meeting any of the following criteria will be excluded: * Inadequate or absent ulnar artery flow at the intended access site on ultrasound * Known ulnar nerve injury or neuropathy affecting the access-side upper limb * Severe pre-existing motor or sensory dysfunction of the access-side hand that would interfere with functional assessment * Emergency coronary procedures that preclude baseline vascular or functional assessment * Participation in another interventional clinical study involving vascular access or intervention in the same upper limb * Local conditions at the intended access site, such as active infection, burn, or extensive scarring * Pregnancy or breastfeeding * Life expectancy less than 6 months