Evolution of radial access in the neurovascular space


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Eric Peterson

The field of neurointervention has seen a dramatic increase in the adoption of radial artery access over the past few years. In this article, Eric Peterson (University of Miami Miller School of Medicine, Miami, USA) discusses the origins of radial access in the field of neurovascular surgery, its rapid rise in popularity, and its future role in the field.

To the casual observer, the rapid adoption of radial access in the field of neurointervention may seem to have materialised out
of thin air. However, closer inspection reveals that the current phenomenon within our field is merely the tipping point of a process that has been decades in the making, which has origins in the field of cardiology. The radial artery was first identified as an alternative access site in 1989, when the Canadian cardiologist Lucien Campeau published the first case series detailing coronary angiography cases using a radial approach.1 In the three decades since that seminal publication, the field of cardiology has built a veritable mountain of prospective, randomised clinical data detailing the safety and benefit of radial artery access which is due to a reduction in access site morbidity compared to traditional femoral artery access. In addition, the field has rigorously outlined the best practices to: 1) safely and efficiently access the radial artery; 2) prevent complications once access has been established, and; 3) safely achieve radial artery haemostasis while allowing for future use of the radial artery as an access site.

Thus, the field of cardiology has provided a detailed understanding of the argument in favour of conversion to a radial approach. In addition, and equally as important, they have provided our field with an evidence-based outline of the optimal technique for transradial access (TRA). In 2015, the European Society of Cardiology (ESC) recommended radial access as a first-line approach for coronary angiography and percutaneous coronary intervention (PCI). This overwhelming clinical evidence has driven adoption of radial access in cardiology over the past several decades to greater than 80% in many European countries. Radial access as an alternative to traditional femoral access in the neurointerventional space was described in individual case reports and series by a handful of institutions from 2000 to 2016, but failed to gain traction within the field during this time. But, beginning in 2017, clinical articles have been published demonstrating not only the feasibility of TRA, but more importantly, leveraging the plethora of cardiology data to make a compelling argument to understand the role of TRA in neurointervention.

Articles have highlighted the incorporation of best practice from cardiology, and have detailed the technical nuance and learning curve in a successful practice transition to TRA as a first-line approach for cerebral angiography and interventions.2–5

The rise of the transradial approach
Since 2017, there has been an exponential increase in the number of publications covering TRA, as well as the number of centres using this approach. This includes multicentre data demonstrating the safety of TRA for PED,6 prospective data on the safety benefit,7 and safety benefit compared to traditional transfemoral access (TFA).8 Specifically, Li et al retrospectively analysed flow diversion cases for cerebral aneurysms from 14 institutions from 2010 to 2019 with an aim to assess complication rates in a large multicentre registry for TRA versus TFA flow diversion. A total of 2,285 patients who underwent aneurysm treatment with flow diversion were analysed. Of these 2,285 patients, 134 (5.86%) were treated with TRA and 2,151 (94.14%) via TFA. There was a significantly higher access site complication rate in the TFA cohort as compared with TRA (2.48%; 95% confidence interval [CI], 2.4–2.57%, vs. 0%; p=0.039). One death resulted from a femoral access site complication. The overall complications rate was also higher in the TFA group (9.02%; 95% CI, 8.15–9.89%) compared with the TRA group (3.73%; 95% CI, 3.13–4.28%; p=0.035). The authors concluded that TRA may be a safer approach for flow diversion to treat cerebral aneurysms at a wide range of locations.

Accordingly, the most recent access guidelines report by the Society of NeuroInterventional Surgery (SNIS) Standards and Guidelines Committee highlighted TRA’s emerging role and codified best practice recommendations.9

Until recently, neurointerventionalists wishing to use a radial approach had no alternative but to appropriate guide catheters built for TFA. The usefulness of these transfemoral catheters relied heavily on the lack of an alternative device designed specifically for radial access. In a field with an unparalleled need for both timely access of any target vessel and a reliable foundation through which neurovascular treatments could be delivered, a need arose for an access system designed specifically to enable TRA for neurovascular procedures. This system would provide trackability and support from a TRA approach, not only superior to current TFA catheters used radially, but more importantly, one that would operate at the level of performance neurointerventionalists are used to in a TFA.

The Rist 079 radial access catheter and Rist radial access selective catheter (Medtronic) were rigorously designed to address the many nuances of TRA for neurovascular procedures. The Rist system, the first radial access system in the neurovascular field, enables the neurointerventionalist to gain the clear access site benefits of TRA, without sacrificing performance, which may occur when utilising TFA catheters for TRA.

The Rist system was designed specifically to allow the patient and physician to enjoy all of the benefits of radial access, with none of the tradeoffs. The Rist 079 is designed specifically to be placed through 7F radial access sheaths that are currently available on the market. Nearly all patients can accommodate these sheaths and they are designed to ensure radial artery patency postprocedure.10 This is in contrast to the sheathless placement of transfemoral neurovascular guide catheters, which lack the critical design features of radial sheaths.

The Rist 079 is designed to be placed into the target vessel coaxially via the selective catheter, ensuring rapid placement of the “base camp” and eliminating the need for catheter exchange. The 079 offers best-in-class trackability, along with the stability required to deliver the spectrum of therapies for haemorrhagic stroke disease. The system diameter was also specifically designed to allow the neurointerventionalist to utilise the support catheter of choice, including the Navien 058 (Medtronic) and Phenom Plus (Medtronic), and perform contrast injections around said support catheters—important tools that are not available with smaller-ID access systems.

I am confident the Rist system will be an indispensable tool in the armamentarium of any neurointerventionalist currently performing or interested in converting their practice to TRA, ensuring safety and satisfaction for both the physician and patient.

Eric Peterson is an associate professor of Radiology and Neurosurgery at the University of Miami Miller School of Medicine, Miami, USA. He has pioneered the radial approach and has authored several publications on the technique.


  1. Campeau L. Percutaneous radial artery approach for coronary angiography. Cathet Cardiovasc Diagn. 1989 Jan; 16(1): 3–
  2. Snelling B, Sur S, Shah SS, et al. Transradial access: lessons learned from cardiology. J Neurointerv Surg. 2018 May; 10(5): 487–
  3. Snelling B, Sur S, Shah SS, et al. Transradial cerebral angiography: techniques and outcomes. J Neurointerv Surg. 2018 Sep; 10(9): 874–
  4. Chen SH, Snelling B, Shah SS, et al. Transradial approach for flow diversion treatment of cerebral aneurysms: a multicenter study. J Neurointerv Surg. 2019 Aug; 11(8): 796–
  5. Snelling B, Sur S, Shah SS, et al. Transradial Approach for Complex Anterior and Posterior Circulation Interventions: Technical Nuances and Feasibility of Using Current Devices. Oper Neurosurg. 2019 Sep 1; 17(3): 293–302.
  6. Li Y, Chen SH, Spiotta AM, et al. Lower complication rates associated with transradial versus transfemoral flow diverting stent placement. J Neurointerv Surg.
  7. Zussman B, Tonetti D, Stone J, et al. A prospective study of the transradial approach for diagnostic cerebral arteriography. J Neurinterv Surg. 2019 Oct; 11(10): 1045‒1049.
  8. Capatano J, Ducruet A, Nguyen C, et al. Propensity-Adjusted Comparative Analysis of Radial Versus Femoral Access for Neurointerventional Treatments. Neurosurgery. 2021 Feb 13 [Published online ahead of print].
  9. Starke RM, Snelling B, Al-Mufti F, et al. Transarterial and transvenous access for neurointerventional surgery: report of the SNIS Standards and Guidelines Committee. J Neurointerv Surg. 2020 Aug; 12(8): 733‒741.
  10. Aminian A, Iglesias JF, Van Mieghem C, et al. First prospective multicenter experience with the 7 French Glidesheath slender for complex transradial coronary interventions. Catheter Cardiovasc Interv. 2017 May; 89(6): 1014‒1020.

See the device manual for detailed information regarding the instructions for use, indications, contraindications, warnings, precautions, and potential adverse events. For further information, contact your local Medtronic representative and/or consult the Medtronic website at medtronic.eu

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