Around 30 to 50 procedures are needed to achieve proficiency for diagnostic cerebral arteriography, the researchers say.
Neurointerventionalists who have newly adopted the right transradial approach can achieve high success rates in a relatively short period of time, according to an analysis published online April 27, 2019, ahead of print in the Journal of NeuroInterventional Surgery.
“Because individual operator learning and group learning are interrelated processes, it is difficult to define the case volumes necessary to achieve competency with the radial approach in isolation; our institutional experience suggests that a busy neurointerventional practice can overcome the basic radial learning curve in several months and after operators each perform about 30 to 50 cases,” write the authors, led by Benjamin M. Zussman, MD (University of Pittsburgh, PA).
Zussman et al compared outcomes of a prospective series of 50 consecutive right transradial diagnostic cerebral arteriograms with their initial experience in 50 patients. At their academic medical center, they use a procedural staging system, which the paper describes as follows:
Stage 1: the right radial artery is punctured and a sheath is inserted into the artery
Stage 2: a diagnostic catheter is advanced to the aortic arch
Stage 3a: the goals of arteriography are achieved with standard techniques, meaning the use of traditional 4-Fr or 5-Fr catheters, 0.035-inch or 0.038-inch guidewires, and exchange-length J-wires
Stage 3b: the goals of arteriography are achieved with adjunctive techniques, meaning any additional nondiagnostic catheters or wires such as long sheaths, intermediate catheters, microcatheters, and microwires
The primary outcome was the ability to achieve the predefined procedural goals using the radial approach. Secondary outcomes included the technical ability to access and inject each supraaortic artery of interest and the incidence of complications.
Overall, the primary outcome was achieved in 98% of patients in the new series, compared with 88% in the initial series (P = 0.05). In one instance, the catheter could not be advanced to the aortic arch due to a radioulnar loop, resulting in a 2% total crossover rate to a transfemoral approach. This crossover rate was lower than the 8% rate seen in the old series (P = 0.16). All supraaortic arteries of interest were accessed and injected with success rates between 93% and 100%. There were no major complications and two minor complications.
“The standardized procedural workflow did not change between our initial series and this study and we identify several factors that we think contributed to our improved performance,” the study authors write. Among these are habituation to ultrasound-guided radial artery cannulation, reformatting Simmons-shaped catheters in the aortic arch, and catheter manipulation and steering into the supraaortic vessels.
“Procedural efficiency improved between the two cohorts, mirroring the advancement in technical ability with practice,” Zussman et al continue. “From the initial study to this study, there was significantly less fluoroscopy time used (22.8 vs 15.7 min; P = 0.002), despite a similar number of vessels injected. This decrease in fluoroscopy time is largely due to improved operator efficiency navigating the aortic arch from the radial approach.”
Additionally, the ability to access and inject the left vertebral artery improved from 59% to 100% (P = 0.014).
Zussman and colleagues note that teamwork appears to help accelerate the learning curve of individual operators “because colleagues rapidly disseminate best practices and strategies to avoid pitfalls to the entire group. Developing familiarity with an alternative approach among nonoperator team members, such as technologists and nurses, is a gradual parallel process that impacts room setup, patient positioning, and effective intraprocedural assistance.”
The authors acknowledge some limitations of their study, including lack of generalizability to centers with only one or few neurointerventionalists or with lower case volumes, as well as potential lack of generalizability to diagnostic cerebral angiography. But they conclude that a high level of efficacy and safety are possible and that “prospective comparison with the transfemoral approach should be the focus of future inquiry.”
Zussman BM, Tonetti DA, Stone J, et al. J NeuroIntervent Surg. 2019;Epub ahead of print.
Zussman reports no relevant conflicts of interest.