An observational study in Radial Artery Occlusion, Vascular Access and Coronary Artery Disease (CAD), sponsored by National and Kapodistrian University of Athens. Recruiting at 2 sites in Greece. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-02-02.
Sponsored by National and Kapodistrian University of Athens · Observational
Coronary angiography and angioplasty are commonly performed through the radial artery at the wrist as this approach is associated with fewer bleeding complications and faster recovery. In some patients, the radial artery becomes occluded after prior procedures, requiring selection of an alternative access site for future coronary interventions.
The ulnar artery is a potential alternative wrist access. However, limited data are available on the safety of using the ulnar artery in the same arm as an occluded radial artery and on the possible effects on hand strength, sensation, and daily hand function.
The goal of this observational study is to evaluate the safety of transulnar access and its effect on hand function in adults with ipsilateral radial artery occlusion undergoing coronary angiography or angioplasty.
The main questions addressed by the study are:
The findings of this study are expected to inform access-site selection, improve patient counseling, and support safer care for patients with radial artery occlusion undergoing coronary procedures.
Transradial access is the preferred approach for coronary angiography and angioplasty because it is associated with reduced bleeding complications and faster recovery compared with femoral access. Radial artery occlusion is a recognized complication of transradial procedures and may limit future use of this access site. In patients with radial artery occlusion, selection of an alternative vascular access is required, particularly when preservation of the contralateral radial artery is clinically important.
The ulnar artery represents an anatomically plausible alternative upper-limb access route, contributing substantially to hand perfusion through the palmar arterial network. However, concerns remain regarding the vascular and functional safety of transulnar access, especially when used ipsilateral to a pre-existing radial artery occlusion. Available evidence is limited and methodologically heterogeneous, with inconsistent assessment of vascular integrity and hand function.
ULNART is a prospective observational cohort designed to evaluate the safety and functional outcomes of transulnar arterial access in patients with ipsilateral radial artery occlusion undergoing coronary angiography or angioplasty. Vascular access selection is determined by the treating physician and is not assigned by the study protocol. The study observes outcomes following transulnar access without influencing procedural decision-making.
Participants undergo standardized baseline and follow-up assessments integrating vascular imaging, objective neuromuscular testing, and patient-reported outcome measures. Color duplex ultrasonography is used to assess upper-limb arterial anatomy and ulnar artery patency, while hand function is evaluated using quantitative strength testing, sensory assessment, and validated questionnaires addressing upper-limb function and cold sensitivity. Assessments are repeated shortly after the procedure and at predefined later time points to evaluate recovery and detect early or delayed access-related effects.
The primary objective is to estimate the incidence of serious access-related vascular and clinical neuromuscular complications. Secondary objectives include characterization of ulnar artery patency, changes in hand strength and sensory function over time, patient-reported functional outcomes, and identification of factors associated with adverse events. Data are collected prospectively using standardized protocols and analyzed according to a prespecified statistical analysis plan appropriate for an observational cohort.
The results of ULNART are expected to provide systematic evidence on the vascular safety and functional impact of transulnar access in patients with radial artery occlusion, supporting informed access-site selection and patient counseling when transradial access is unavailable or clinically undesirable.
296 studies on the registry are indexed under Arterial Occlusive Diseases; 46 are open to participants now.
This study's planned enrollment of 127 is below the median of 183 across 75 observational studies indexed under Arterial Occlusive Diseases.
Browse Arterial Occlusive Diseases studies →National and Kapodistrian University of Athens is the lead sponsor of 168 studies on the registry; 50 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Participants are recruited from cardiac catheterization laboratories and cardiology services of two tertiary-care public hospitals in Greece, including high-volume referral centers performing invasive coronary procedures. The study population represents adults undergoing routine elective coronary angiography or angioplasty in these hospital settings, where vascular access decisions are made as part of standard clinical practice.
Participants must meet all of the following criteria to be eligible:
Exclusion Criteria
Participants meeting any of the following criteria will be excluded:
Adults with documented radial artery occlusion undergoing elective coronary angiography or angioplasty, in whom transulnar arterial access ipsilateral to the occluded radial artery is selected by the treating physician. Participants are followed prospectively to assess vascular safety and hand function outcomes.
Incidence of Serious Access-Related Vascular and Clinical Neuromuscular Complications
Composite incidence of serious vascular and clinical neuromuscular complications attributable to transulnar arterial access ipsilateral to radial artery occlusion. Serious vascular events include acute hand ischemia, symptomatic ulnar artery occlusion, flow-limiting dissection requiring treatment, pseudoaneurysm or arteriovenous fistula requiring intervention, major access-site hematoma, or major bleeding. Clinical neuromuscular events include new, clinically evident motor or sensory deficits in the ulnar nerve distribution that persist or require targeted therapy.
Time frame: 30 days
Number of Access Attempts
Number of puncture attempts required to obtain successful vascular access
Time frame: During the index procedure
Technical Success Without Access-Site Crossover
Successful completion of coronary angiography or angioplasty via intended transulnar access without conversion to an alternative vascular access site.
Time frame: During the index procedure
Procedure Duration
Total procedural time from vascular access to sheath removal
Time frame: During the index procedure
Ulnar Artery Patency
Assessment of ulnar artery patency and flow characteristics using color duplex ultrasonography, including presence of antegrade flow and absence of occlusion or flow-limiting abnormalities.
Time frame: Within 24 hours, 30 days, and 180 days
Early Access-Related Vascular and Neuromuscular Complications
Incidence of access-related vascular and neurologic complications occurring within 24 hours after removal of the hemostatic device, including minor bleeding, hematoma, reversible neurologic symptoms, and access-site findings not meeting criteria for the primary endpoint.
Time frame: Within 24 hours after band removal
Change in Handgrip Strength
Change from baseline in handgrip strength of the access-side hand measured with a calibrated dynamometer.
Time frame: Within 24 hours, 30 days, and 180 days
Change in Key Pinch Strength
Change from baseline in key (lateral) pinch strength of the access-side hand measured with a calibrated pinch gauge.
Time frame: Within 24 hours, 30 days, and 180 days
Change in Sensory Function
Change from baseline in tactile sensation of the ulnar nerve distribution assessed using standardized light-touch threshold testing.
Time frame: Within 24 hours, 30 days, and 180 days
Change in Patient-Reported Upper-Limb Function
Change from baseline in patient-reported upper-limb function assessed using validated questionnaires evaluating disability and cold sensitivity.
Time frame: 10 days, 30 days and 180 days
Late Vascular or Neuromuscular Complications
Incidence of vascular or neurologic complications occurring beyond 30 days that do not meet primary endpoint criteria.
Time frame: 6 months
Plan to share: Yes — De-identified individual participant data that underlie the results reported in publications arising from this study will be made available, including demographic variables, procedural characteristics, vascular imaging findings, functional test results, and patient-reported outcome measures. A corresponding data dictionary and study protocol will be provided. Data will be shared after publication of the primary results, upon reasonable request, subject to approval by the study investigators and completion of a data-use agreement, in accordance with applicable ethical approvals and data protection regulations.
Supporting information: Study protocol, Sap, Analytic code
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
National and Kapodistrian University of Athens