Evaluating Lumen Size of Radial and Ulnar Arteries During Mechanical Thrombectomy

Introduction Mechanical thrombectomy has become the standard of care for acute ischemic stroke due to large vessel occlusion, with transfemoral access representing the most utilized approach. Nevertheless, alternative access routes, particularly trans‐radial and trans‐ulnar, have gained increasing interest in neurointervention given their established safety profile in interventional cardiology and potential to reduce serious access‐related complications. The feasibility of these approaches, however, is largely dependent on vessel caliber relative to sheath size requirements. In this study, we systematically evaluated the inner diameters of the radial and ulnar arteries in patients who underwent thrombectomy to determine whether this patient population has vessel calibers with adequate dimensions to support neuroendovascular interventions. Many previous studies investigating the average radial and ulnar artery diameters have used the tunica media and tunica adventitia interface as the reference point due to limitations of ultrasound. However, with new high‐resolution ultrasound we can now measure from tunica intima to tunica intima allowing for a much more accurate representation of the true lumen size. Methods We performed ultrasound‐based measurements of the radial and ulnar arteries in patients undergoing thrombectomy. Inner arterial diameter was defined as the lumen dimension measured from the intimal surface on one side to the intimal surface on the opposite side of the arterial wall. Measurements were compared with sheath size requirements commonly used in neuroendovascular procedures. Results A total of 61 patients were evaluated via high resolution ultrasonography with an average radial and ulnar size of 0.20cm ± 0.003cm and 0.15cm ± 0.003cm respectively. Risk factors including hypertension, prior stroke or TIA, type 2 diabetes, hyperlipidemia, atrial fibrillation, heart failure, myocardial infarction, and kidney disease were evaluated for significant differences from the average patient population. Only history of heart failure showed a significant increase in ulnar size from 0.15cm to 0.19cm (p value = 0.027). Conclusions Our findings provide direct evidence of true lumen diameter of the radial and ulnar arteries in thrombectomy population. In our practice, we have successfully utilized a 6 French (Fr) catheter for neurointerventional procedures, which has an outer diameter of 0.244 cm. Current evidence indicates that the catheter diameter can safely exceed the artery diameter by up to 10‐20%. Most studies measure artery size based on tunica media and tunica adventitia interface, which may lead to an overestimation of the true vessel size. In contrast, our current study utilized intima to intima measurements, providing a more accurate representation of the intravascular space and better reflecting the actual vessel diameter available to accommodate the catheter. These results may help guide patient selection and expand the role of trans‐radial and trans‐ulnar approaches in neurointervention.