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- Neuroradiol J
- v.36(2); 2023 Apr
- PMC10034707
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Neuroradiol J. 2023 Apr; 36(2): 163–168.
Published online 2022 Jun 24. doi:10.1177/19714009221111090
PMCID: PMC10034707
PMID: 35749090
Mohamed Yaser Arafath,1 Vikas Bhatia,
1 Ajay Kumar,1 Rajeev Chauhan,2 Anuj Prabhakar,1 SK Gupta,3 and Paramjeet Singh1
Author information Copyright and License information PMC Disclaimer
Abstract
Background
To evaluate factors that influence the successful cannulation of intracranial vesselsusing a transradial approach.
Methods
A total of 61 transradial diagnostic angiograms were evaluated in a tertiary carecenter from July 2020 to December 2021. We evaluated the learning curve and aortic archvessel factors that may influence the cannulation of intracranial major vessels using atransradial approach.
Results
Learning curve for the procedure was established after 21 cases. We were successful incannulating the supra-aortic arteries except in 4 cases where we were unable tocannulate the left VA (vertebral artery). Significant positive correlation was seenbetween time to Sim (Simmons curve) formation and aortic arch diameter(p = .002). Significant positive correlation was also seen betweenleft VA take-off angle and time to cannulate left VA (p = .001) andnegative correlation was noted between left CCA (common carotid artery) take-off angleand time to cannulate left CCA (p = .001).
Conclusion
Transradial approach is a feasible and safe approach for performing cerebralangiography. Multiple factors can influence the procedure time and successfulcannulation of intracranial vessels. With the availability of radial specific hardwarein the future, procedural success and time taken to complete the procedure mayimprove.
Keywords: Transradial approach, transradial access, diagnostic cerebral angiography, neurointervention, take-off angles, time to cannulate, fluoroscopy time
Introduction
Vascular access is a very important step for the success of any interventional procedure.Traditionally, the transfemoral route has been widely practiced by the interventionalneuroradiologists owing to the familiarity with the approach. Transfemoral approach isassociated with increased post procedure recovery time which is worrisome for ambulatorypatients.1,2 This led to theintroduction of novel yet practical and patient friendly transradial approach into the fieldof neurointervention.3 Adaptability of the approach has significantly increased in the interventionalneuroradiology as evidenced by the growing number of papers on the transradial technique inrecent years.4–6 We sought to incorporateour own experience with this technique in this research, as well as discuss the numerousaspects that contribute to the transradial approach’s success.
Materials and methods
This was a prospective single center analytical study approved by the institutional ethicscommittee. We included all the patients >18years who were indicated for diagnosticcerebral angiography according to our department protocol. Patients with radial arterydiameter <1.8mm, history of Raynaud’s phenomenon, severe atherosclerotic disease, andunhealthy puncture site were excluded. All procedures were carried out by single operator(VB) with 8 years of experience in field of neurointervention
Computed tomography angiography (CTA) head and neck was done prior to procedure formeasurement of aorta metrics and take-off angles of the neck vessels. If CTA of the neck wasnot available prior to procedure, TOF MRA (time of flight magnetic resonance angiography)neck vessels was done post procedure.
Anatomy of the arch of aorta and neck vessels
Type of the arch, great vessel anomalies, diameter of aortic arch, take-off angles ofgreat vessels and bilateral vertebral arteries were recorded by two neuroradiologists andmean values were taken. Aortic arch diameter was measured on all three planes with valuesaveraged. Anteroposterior span and mediolateral span were considered as surrogate markersfor aortic unwinding. Take-off angles of brachiocephalic trunk, bilateral CCAs, andbilateral subclavian arteries were measured using spine as the reference line as mentionedin previous literature.7,8 Forbilateral vertebral arteries, angles were measured using a tangential line along thesubclavian artery as reference with direction of flow marking the angle (Figure 1).
Figure 1.
Measurement technique employed to measure the angles of left CCA (a) and RVA(b).
Procedural details
Right sided radial artery was the principal access site in our study. Entire procedurewas done under local anesthesia. Sedation and anxiolytics were used as per need inuncooperative patients and patients with painful radial spasm.9 In most of the cases, radial access was achieved using ultrasound guidance and 21Gneedle with sheath inserted using Seldinger technique (Glide Slender sheath 5F, terumo, Japan).10 Radial co*cktail regimen used after sheath insertion was Inj. Diltiazem 2.5mg, injNitroglycerin 200micrograms and inj. Heparin 50U/kg which was injected slowly over 30s.11 Heparin dose was tapered according to procedure duration. However, there was noneed of repeat heparinization in any of the cases. Pulse oximeter reading of ipsilateralthumb was recorded throughout the procedure to look for any compromised blood flow to thehand.
After co*cktail injection, radial artery angiogram was taken visualizing the elbow. Radialartery anatomy and variations were assessed. Using roadmap angiography, arm vessel wastraversed using over the wire technique (Glide catheter 5F- Simmons/sidewinder curve 2& 0.035 Glidewire, Terumo intervention system, Japan).
Time durations for Sim formation and cannulation of each individual vessel from arch weremeasured with stop clock. Timings for cannulation of the artery were noted from theformation of Sim curve till the stabilization of the catheter in the concerned vessel.Crossover to alternate access was done in cases of failure to achieve the diagnosticindication.
Hemostasis
Post-procedure hemostasis was achieved by transradial compression band following patenthemostasis technique.12,13Patient recovery duration, wellbeing, and mobility were assessed post procedure.
Follow-up with radial artery doppler was done at the time of discharge or after 3dayspost procedure whichever was earlier.
Statistical analysis
Continuous data was mentioned as mean, range, and standard deviation. The normality ofquantitative data was checked by measures of cannons and sparrows tests of Normality.Spearman correlation coefficient was calculated as the data was not normally distributedto see strength of the relation between take-off angles and time taken to cannulate thevessels and between aorta metrics and Sim curve formation time. Linear regression analysiswas carried out for contribution of the various variables with significant correlation(i.e., arch of aorta diameter and time to Sim formation, take-off angles of left CCA andleft VA) with time taken.
Correlation and regression analysis were carried out for the entire study population andpart of the study population after the learning curve was achieved (i.e., After 21cases).
All the statistical tests were two-sided and were performed at a significance level of α= 0.05. Analysis was conducted using IBM SPSS STATISTICS (version 22.0)
Results
There were a total of 61 patients out of which 70.4% were males (n = 43)and 29.6% patients were females (n = 18) with average age of 43.8years(20–65years). One included case was crossed over from transfemoral approach due todifficult arch. Left transradial and distal transradial approaches were excluded from thestudy (n = 4). 1 case was crossed over to transfemoral approach due toradial artery perforation, 2 cases due to severe radial artery spasm, and 1 case due tofailed Sim formation in a case of aberrant subclavian artery.
Indications of cerebral angiography were broadly classified into 4 categories. Follow-up ofvascular malformations (39%) included intracranial brain arterio-venous malformations, duralarterio-venous fistulas, and 1 case of facial malformation. CTA negative intracranial bleedpopulation (34%) included both subarachnoid hemorrhage and intraparenchymal hemorrhage.There was also a case of CTA negative ptosis. Other groups were predominantly follow-up ofaneurysm post coiling or clipping (13%) and angiographies done for pretherapeutic planningfor aneurysms (14%).
Mean radial artery diameter was 2.06mm (range 1.8–2.3mm). Post co*cktail average diameterwas 2.14mm (range 1.9–2.4). There was average 0.1mm increase post co*cktail diameter (p–.003). 55 cases were done with counter puncture technique and 6 cases were done withtactile technique.
Most common radial artery variation encountered was high origin of radial artery(n = 11) (18%). Tortuous course with loop was seen in 2 cases (3%)
Overall mean puncture time was 105s, whereas after 21 cases, it had reduced to 68s.Average number of attempts was 1.7, whereas after 21 cases, it improved to 1.2. (21 cases isthe learning curve milestone in our study as described later).
We experienced one case of radial artery dissection and one case of radial arteryperforation diagnosed by radial angiogram. These cases were conservatively managed withcrossover to transfemoral and left transradial approach, respectively. Radial arterythrombosis in one of the cases was identified on follow-up ultrasound. Radial artery spasmwas encountered in 23.8% (n = 14) patients identified by radial arteryangiogram. Out of this, 22% (n = 12) had clinical spasm also. Majority ofthem were managed by mild sedation and intraarterial spasmolytics. Except 2 cases werecrossover to transfemoral approach was required.
Learning curves
Learning curves throughout the course of study can be depicted by line graph drawn alongthe course of the study against the time taken to cannulate various arteries by the singleoperator (Figure 2). Learningcurves were considered established if the fluctuations between time has reached a fairlyplateau level with minimum standard deviation. Learning curve for Rt CCA and Rt VA wereachieved within 10 and 12 cases, respectively. Lt CCA time normalized after 16 cases,whereas Lt VA achieved after 21 cases over the course of study. So, in our study, 21 caseswere considered as the checkpoint of the learning curve.
Figure 2.
Line graph along the course of study depicting the time taken to cannulate variousarteries (a–d).
Mean time to Sim formation was 24.25s. Strong positive correlation was seen between archof aorta diameter and time to Sim formation (Table 1). For every 1mm increase in the arch ofaorta diameter, time to Sim formation increases by 3.2s.
Table 2.
Depicting the results of correlation of the various arteries and time tocannulate.
| Artery | Mean take-off angle (range) | Mean time to cannulate (range) | Spearman’s Rho correlation | p value |
|---|---|---|---|---|
| Rt CCA | 30.09° (11.4–55.6) | 40.03s | −0.3 | .01 |
| Rt VA | 84.4° (30.7–140.5) | 23.9s | 0.14 | .2 |
| Lt CCA | 21.2° (8.5–89) | 91.5s (6–179) | −0.6 | <.0001 |
| Lt VA | 68.97° (6.6–128.2) | 90s (8–215) | 0.8 | <.0001 |
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The correlation of various arteries with time to successful cannulation is shown in Table 2. There was moderatenegative correlation between Lt CCA take-off angle and time to cannulate. For every 1°,increase in angle time to cannulate decreased by 2.3s (Figure 3(a)). Strong positive correlation was alsoseen between Lt VA take-off angle and time to cannulate with every 1° increase in angletime to cannulate increased by 4.4s (Figure 3(b)). We were successful in achieving the goal of diagnostic cerebralangiography with 100% success rate in cannulating Rt CCA, Rt VA and Lt CCA. 10% failurerate in cannulating the left VA (n = 4). 3 of the patients had angle morethan 90° and 1 had tortuous course of left subclavian artery along the clavicle not givingsupport for the catheter tracking over the wire along the left VA.
Table 1.
Depicting the correlation values of aorta metrics with time to Sim formation.
| Mean, mm | Spearman’s Rho | p value | |
|---|---|---|---|
| Arch of aorta diameter | 24.25 | 0.78 | .0002 |
| Anteroposterior span | 66.89 | 0.27 | .04 |
| Mediolateral span | 49.74 | 0.19 | .04 |
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Figure 3.
Scatter plot depicting the correlation between various arteries take-off angles andtime to hook the arteries.(a) Moderate negative correlation between Lt CCA take-offangle and time (p = .001), (b) strong positive correlation betweenLt VA take-off angle and time (p = .001).
Our total fluoroscopy time for the cases was on an average of ∼15.2mins (10.2–32mins)with average dose area product 88000cGy.cm2. After 21 cases, fluoroscopy timeranged from 10.2 to 18.8mins.
Discussion
This study can be divided into two parts—the first section focuses on overcoming theneurointerventionist’s learning curve related with transradial access, while the secondevaluates the many aspects affecting the transradial access’s safety and efficacy.
Evaluation of the safety was the important consideration of this study. We did notencounter any major intracranial complications in our study. There was one case of radialartery perforation in the initial part of the study which led to crossover to transfemoralaccess. Fortunately, the patient responded to conservative management without development ofany major hematoma. We encountered one case of right radial artery dissection again in theinitial part of the study with crossover to the left transradial approach. Patient wasmanaged conservatively during the hospital stay. Follow-up USG doppler of patient’s rightradial artery showed monophasic flow however with no evidence of compromised blood flow inthe right hand.
Once the learning curve for puncture has reached a fair plateau, we did not encounter anymajor arterial complications like perforation or dissection. Most common complicationencountered was radial artery spasm (n = 14). This is inclusive of bothradiological and clinical spasm; however, management was done only for clinical spasm whenpatient complains of pain. Most of the cases, the spasm was managed conservatively with mildsedation and intraarterial spasmolytics, that is, NTG (nitroglycerin).
In two cases, there was severe vasospasm with risk of catheter entrapment. Access wasabandoned with crossover to femoral approach. Moderate analgesia was given with transfemoralsubclavian artery run showing resolution of the spasm.
Two cases of left transradial and 2 distal transradial access were excluded from thestudy.
Though many authors suggest to divide the procedure into various steps for analysis asbeginners we encountered difficulty in following three steps.5,14
□ Radial artery puncture
□ Formation of the Simmons catheter
□ Cannulating the supra-aortic vessels.
These steps can be considered as important milestones in overcoming the learning curve oftransradial access. In the first case, access was achieved after 4 attempts but reduced tosingle or two attempts in the later part of the study. Though incidence of radial arteryspasm is partly associated with number of attempts, we did not find any significantcorrelation in our study mainly owing to small sample size.8
Radial artery angiogram was usually taken after the access to look for variant anatomy.High origin of radial artery was the most common variant anatomy noted. Small radial loop(<360°) and tortuous radial artery course was seen in two of our cases; however, therewas no statistically significant difference in the time taken from radial artery to arch.Data of variant anatomy was also limited in number to reach a conclusion.
Hydrophilic sheath with reduced lateral profile and hydrophilic Simmons 2 catheter were theworkhorse of transradial access in our study.
Sim curve formation was done through various ways as previously described, most commonbeing in the aortic arch, ascending aorta and reflecting off the aortic valve. Aorta metricsused in our study such as aortic arch diameter, anterolateral span, and mediolateral spanserved as surrogate markers of arch unwinding. Measurements of the aorta were done accordingto the method described by Knox et al.7
Our study found significant positive correlation between time to Sim formation and aorticarch diameter. For every 1mm increase in the arch of aorta diameter time to Sim formationincreases by 3.2s. This was in concordance with the study done by Khan et al.8 However, the study did not perform regression analysis of individual Sim formationtime and aortic arch diameter as in our study. Formation of Sim just by rotating thecatheter in aortic arch is simplest and quickest way; however, it becomes difficult in agedpatients due to unwinding of aorta.15 As the aortic arch diameter increases, support to the catheter to form the curve inthe arch is lost so the curve has to be formed either in the ascending aorta or reflectingoff the aortic valve.
We had one case crossed over to transfemoral approach due to aberrant right subclavianartery leading to failed Sim curve formation.
Knox et al.7 have shown significant correlation with take-off angles and reperfusion time is casesof mechanical thrombectomy via transfemoral approach. We utilized similar measurementtechniques for take-off angles of right and left CCA as it was more reproducible. Somechanges in bilateral vertebral artery angle measurements which were done according to thecourse of the subclavian artery as described by Khan et al.8
Learning curve for left vertebral artery was steep when compared to rest of thesupra-aortic vessels. Most significant correlation was seen with left vertebral arterytake-off angle and time taken to cannulate it (Spearman = +0.72). More obtuse the take-offangles, more time was taken to hook the artery. All cases with take-off angle >90°required the usage of road-mapping increasing the time further. In our data, we were able todeduce that for each degree increase in angle time to cannulate increases by 4.4s.
There was failure in cannulating the left vertebral arteries in 4 cases out of which 3 hadobtuse take-off angle. Remaining one case had tortuous course of left subclavian artery withacute bend at origin of left vertebral artery. Despite the acute origin of vertebral artery,cannulation could not happen due to lack of support from the subclavian artery. None of thefailed left VA cases were crossed over to transfemoral approach due to the fulfillment ofthe required indication.
Learning curve for left common carotid artery was moderately steep. We had moderatenegative correlation of left CCA take-off angle with time taken to cannulate (Spearman =−0.65). The relationship further strengthened with addition of common and close origin ofleft common carotid artery with right brachiocephalic trunk. However, none of thesemeasurements carried significance when considered alone except the take-off angle. For every1° increase in take-off angle, the time taken to cannulate reduced by 2.2s. Time was alsoparadoxically increased with >80°; however, it did not reach statistical significance inour study and were considered outliers (n = 2). One case of crossover fromtransfemoral approach due to failed left CCA catherization was seen in our study with leftCCA take-off angle of 83°. This was successfully achieved with transradial approach;however, time taken was higher when compared to mean left CCA angle. This might requirefurther data and analysis for accurate interpretation.
Learning curve of right vertebral artery and right common carotid artery were not difficultand showed no significant correlation with their respective take-off angles. Right vertebralartery was cannulated directly without the need of the formation of the Sim’s curve in allthe cases.
When compared to earlier studies, our study’s learning curves appear to be completed sooner(21 vs 55). For novices, we recommend doing at least 50–100 cases on a continuous basis toobtain a firm grasp on the method, as there was significant diversity in learning curvesbetween individuals.
Our study was in concordance with the results described by khan et al., except for theangle of left vertebral artery. We discovered difficult cannulation at the obtuse left VAangle by transradial approach, whereas Khan et al. described difficulty in the acutetake-off angle of the left VA. In our study, however, we exclusively utilized the Sim 2catheter for all procedures and did not transfer to a different catheter in the event ofdifficulty. The disparity between the Sim’s primary curve and obtuse VA angle explains ourfindings. In our investigation, the fastest fluoroscopy time was 10.2min. In the firsteight cases, it took 28–35min, but after 21 cases, it took 10.2–18min. In comparison tothe earlier study by Kenawy et al.,16 this was slightly higher. However, as compared to their study, our sample size wassubstantially smaller.
On follow-up patients, satisfactory score was on an average of 7.6 out of 10. 6 patientsgave score less than 5. Out of these 6 patients, 4 patients had pain due to moderate spasmwhich required NTG for control. One patient had follow-up radial artery thrombosis and otherpatient developed chronic mild pain in the forearm which persisted more than 3 months postprocedure.
Limitations
This was a single center study. Reduced sample size is a limitation to our study. Ourstudy may be prone to selection bias as all the consecutive patients referred fordiagnostic angiogram were not included in the study.
We have shown these results using a single type of catheter only although dedicatedradial hardware has yet to evolve and with greater availability may reduce the problemsregarding successful cannulation of intracranial vessels using a transradial approach.
Conclusion
Transradial approach is feasible and bound to become a routine care in neurointerventionsin the near future. Interventionists should overcome the learning curve and consider thefactors that may influence the successful cannulation of intracranial arteries when atransradial approach is used as compared to transfemoral approach.
Footnotes
The author(s) declared no potential conflicts of interest with respect to the research,authorship, and/or publication of this article.
Funding: The author(s) received no financial support for the research, authorship, and/orpublication of this article.
Author contributions: All authors of this work met ICMJE criteria for authorship and made substantialcontributions to the conception and design, acquisition of data, analysis andinterpretation of data, drafting, critical revising, and final approval of thismanuscript
ORCID iD
Vikas Bhatia https:/orcid.org/0000-0003-3700-8025
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