Original Contribution

Balloon-Assisted Tracking Use Reduces Radial Artery Access Failure in an Experienced Radial Center and is Feasible During Primary PCI for STEMI

Daniel Obaid, MBBch, PhD;  Ahmed Hailan, MBBS;  Alexander Chase, MBBch, PhD;  Stephen Dorman, MBBch;  Geraint Jenkins, MBBch;  Adrian Raybould, MBBS;  Mark Ramsey, MBBS, MD;  Phillip Thomas, MBBS;  David Smith, MBBS, MD;  Adrian Ionescu, MD

Daniel Obaid, MBBch, PhD;  Ahmed Hailan, MBBS;  Alexander Chase, MBBch, PhD;  Stephen Dorman, MBBch;  Geraint Jenkins, MBBch;  Adrian Raybould, MBBS;  Mark Ramsey, MBBS, MD;  Phillip Thomas, MBBS;  David Smith, MBBS, MD;  Adrian Ionescu, MD

Abstract: Objective. This prospective study assesses balloon-assisted tracking (BAT) in reducing radial access failure during percutaneous coronary intervention (PCI). Background. Arterial spasm prevents PCI from the radial artery in a small percentage of cases. Methods. A total of 2223 consecutive patients undergoing PCI from the radial approach were analyzed. Radial access failure mode and requirement for crossover to femoral access during a 12-month run-in period were compared with the following 14-month period with routine BAT usage. Results. During the 14-month study period, 1334 radial PCIs were attempted. Twenty-six patients switched to femoral at an early stage, while 76 encountered radial spasm and underwent successful BAT in 69 cases (91%), giving a total crossover rate to femoral of 33/1334 (2.5%). Utilizing BAT rather than a femoral puncture reduced our institution’s radial-femoral crossover rate from 7.6% to 2.5% (P<.01), which is also significantly lower than the radial-femoral crossover rate in the 12 months before BAT implementation (6.1%; P<.01). Mean procedure times were similar for those requiring BAT compared with conventional radial access (51.3 ± 21.3 min vs 47.9 ± 23.7 min; P=.23), and those crossing straight to femoral (BAT not attempted) (60.7 ± 31.9 min; P=.10). Mean first device/balloon time for the BAT-assisted primary PCI cases (22.6 ± 9.4 min) was similar to cases that had radial difficulties and converted to femoral without attempting BAT (25.8 ± 13.4 min; P=.54). Conclusion. BAT allowed catheter passage despite radial spasm in 91% of cases, significantly reducing the institution’s rate of femoral crossover. During radial spasm in primary PCI, using BAT did not delay reperfusion compared with femoral crossover.

J INVASIVE CARDIOL 2017;29(7):219-224.

Key words: arterial access, percutaneous coronary intervention, radial approach, balloon-assisted tracking

Radial arterial access for coronary intervention is associated with fewer access-site complications than femoral arterial access.1-4 Radial access also reduces adverse clinical events including major bleeding and mortality in patients undergoing percutaneous coronary intervention (PCI) for acute coronary syndromes.5 Despite this, radial access PCI in the United States has historically been low, at 16% in 2012,6 increasing more recently but still accounting for only approximately one-third of cases. Radial access gives a particular advantage in primary PCI,7-9 but adoption in the United States is even lower, at <10%.6,10 This may be due to operator concerns regarding delays in achieving reperfusion, or the potential requirement for crossover to femoral arterial access. While experienced radial operators achieve similar procedural durations and success rates using radial arterial access for PCI as compared with femoral arterial access,2 there remains a proportion of radial procedures that require crossover to femoral access, with the most common reason being inability to advance the guide catheter into the aortic root due mainly to radial artery spasm and also due to radial, brachial, or subclavian artery tortuosity.11 Until recently, inability to deliver catheters through the arm arteries mandated a second arterial puncture (either to contralateral radial artery or, most commonly, to the femoral artery). However, Patel et al have recently described the balloon-assisted tracking (BAT) technique, which can overcome radial spasm and difficult anatomy and allow continuation of the procedure through the initial arterial puncture.12,13 We evaluated the feasibility of using BAT routinely on radial arterial access procedural success rate and any reduction in the need for femoral artery crossover.


Study population. The study was performed in a tertiary cardiac center with eight experienced interventional cardiologists. All operators are >10 years post training, have performed at least 1000 PCIs in total, and were experienced in the radial approach (performing more than 80% of all cases by this route). We included all consecutive patients between May 2013 and August 2015 who had coronary intervention with 6 Fr radial approach as the initial selected route of access with routine BAT usage adopted in May 2014. We excluded cases where femoral access was the initial chosen access site (eg, absent radial pulses or where >6 Fr gauge access was required for complex PCI procedures).

Radial access for cardiac catheterization. Radial arterial access was secured after local anesthesia with 1% subcutaneous lidocaine, using the Seldinger technique and a radial kit with a 6 Fr short (10 cm) Glidesheath (Terumo). Intraarterial sheath location was confirmed with an arterial pressure trace, and then 250-500 µg of intraarterial glyceryl trinitrate (GTN) was given to promote arterial dilation. Verapamil (1-5 mg) could be given at the discretion of the operator. A standard 0.035˝ J-tipped guidewire was then advanced into the radial artery followed by a 5 Fr diagnostic or 6 Fr guide catheter, depending on the clinical situation. A weight-adjusted dose of heparin was given into the ascending aorta through the catheter. If a 5 Fr diagnostic catheter was used to obtain initial diagnostic images, this was exchanged for a 6 Fr guide catheter prior to PCI. If it was impossible to advance the catheter, then an arm angiogram was taken. If this showed that the guidewire had taken the route of a small recurrent radial artery, then it was manipulated back into larger-caliber vessels if possible. If 6 Fr guide-catheter advancement was prevented by spasm that persisted in spite of a second dose of intraarterial GTN, ± intraarterial verapamil or tortuosity in the radial and/or brachial arteries (Figure 1), the operator used the BAT technique as described below. Prior to this, our standard approach would have been to downsize to a 5 Fr guide catheter if appropriate (limiting the options for thrombus aspiration, intravascular imaging, and more complex interventional techniques) and if this failed, switch to the femoral approach, with its attendant higher risk of bleeding. 

The BAT technique. The BAT technique has been previously described;12 briefly, it involves advancing a 0.014˝ angioplasty wire through the guide catheter in the radial artery, beyond the tortuous or spastic arterial segment that precludes catheter advancement to the ascending aorta. Often, this requires withdrawing the catheter a few millimeters to allow advancement of the wire if there is significant vessel spasm. The wire is advanced toward the aorta and anchored; a 15-20 mm semicompliant angioplasty balloon (2.0 mm in diameter) is then thread over it and positioned halfway out of the guide catheter. Once in position, the balloon is inflated to 3-6 atm and the balloon and the catheter are then advanced en bloc by exerting a constant push. The protruding balloon maintains the coaxial alignment of the catheter and of the artery, resulting in smooth and usually completely painless passage across the spastic or tortuous segment (Figure 2). 

Data collection. We retrospectively recorded the prevalence and mode of radial access failure and requirement for crossover from radial to femoral artery during a 12-month run-in period. This was compared with radial arterial access failure prospectively collected during the following 14-month period when routine BAT usage was introduced. The success rate for the BAT technique and duration and fluoroscopy times of all procedures were compared. We also analyzed the time from procedure start to first device use/balloon inflation during primary PCI for ST-elevation myocardial infarction to evaluate the effectiveness of BAT in these procedures. 

Statistics. Analysis was performed using Graphpad Prism 6. Continuous variables were expressed as means ± standard deviations and compared with the Student’s t-test (for normally distributed variables) and ANOVA for multiple group analysis. Categorical variables were compared with the Chi-squared test. All analyses were by intention to treat (BAT attempted whether successful or not). 


A total of 2223 patients underwent PCI in which 6 Fr radial was the default access strategy (2167 right radial, 56 left radial). During the pre-BAT period (12 months from May 2013 to May 2014), a total of 889 cases were performed; of these, 17 required immediate crossover to femoral artery due to inability to cannulate the radial artery or a radial artery too small to advance the 6 Fr sheath. Of the remaining 872 cases, catheter advancement was not possible in 55 cases due to tortuosity or spasm. In 18 cases (2%), downsizing to a 5 Fr guide catheter was performed and allowed completion of the case, while the remaining 37 required crossover to femoral access. Thus, during the pre-BAT period, 54/889 (6.1%) required crossover from radial to femoral access.

During the 14-month study period between May 2014 and July 2015, a total of 1334 radial arterial cases were performed. Twenty-six required crossover to femoral access at an early stage due to inability to cannulate the radial artery or a radial artery too small to accept a 6 Fr sheath. Of the remaining 1308 cases, a total of 76 encountered radial spasm due to tortuous anatomy or after catheter manipulation or exchange, which persisted despite vasodilator cocktail and prevented engagement of a 6 Fr catheter. If a femoral puncture had been used to complete these procedures, then the radial-femoral crossover rate would have been 102/1334 (7.6%). However, BAT was attempted in all these cases and it succeeded in 69 cases (91%). This gave a total radial-femoral crossover rate of 33/1334 (2.5%) during the study period. This meant that by utilizing BAT in these cases rather than a femoral puncture during the study period, our institution’s radial-femoral crossover rate fell from a potential 7.6% to 2.5% (P<.01) and was also significantly lower than the radial-femoral crossover rate in the 12 months prior to BAT implementation (6.1% vs 2.5%; P<.01).

Of the patients who required BAT to complete the procedure, 7 presented with stable angina, 39 presented with non-ST elevation acute coronary syndromes, and 30 underwent primary PCI for acute ST-elevation myocardial infarction. Patients requiring BAT were more likely to be female (46% vs 28%; P<.01), but the mode of presentation, mean patient age, mean number of stents, and usage of periprocedural intracoronary imaging or pressure-wire assessment of fractional flow reserve were not significantly different between the patients requiring BAT and the patients undergoing uncomplicated radial access PCI (Table 1). PCI was successful in all cases when BAT was utilized. 

Procedures requiring BAT took 51.3 ± 21.3 min to complete (3.4 min longer) compared with conventional radial access PCIs not requiring BAT (47.9 ± 23.7 min), which was not statistically significant (P=.23). Importantly, when radial access was problematic, using the alternative strategy of straight to femoral crossover (BAT not attempted), the mean total procedure time (60.7 ± 31.9 min) was on average 9.4 min longer than when BAT was used, which was not statistically significant (P=.10). The BAT procedure required an average of 66 sec of additional fluoroscopy time (12.5 ± 6.1 min) compared with conventional radial PCI (11.4 ± 8.4 min) and 12 sec longer than the cases that went straight to femoral crossover (12.3 ± 11.7 min), which was not statistically significant for either (P=.26 and P=.88, respectively) (Table 1). 

There did not appear to be a significant learning curve in adopting BAT, with the procedure times of the first one-third of cases (n = 25) utilizing BAT not significantly longer than the last one-third (n = 25) (52.2 ± 31.4 min vs 55.2 ± 25.9 min, respectively; P=.72). All eight operators were able to utilize the technique with high success rates (>80%).

There were 818 primary PCIs during the total study period, with a median door to balloon time (defined as door to procedure start and procedure start to first device) of 44 min (interquartile range, 30-66 min). During the BAT study period, 30 of the 472 primary PCIs (6.4%) encountered difficulty with tracking a 6 Fr guide catheter to the aorta. BAT was used routinely, with success in 25 cases (83%) (Table 2). There was a significant difference in the time from procedure start to first device/balloon time between the cases depending on whether there were difficulties with radial access or not (P<.001). The procedure start to first device/balloon time for the BAT-assisted primary PCIs was 22.6 ± 9.4 min. This was significantly longer (mean, 5.4 min) than in the conventional radial access primary PCI (17.2 ± 11.8 min; P=.01) during the same period and significantly longer (mean, 6.3 min) than for conventional radial access primary PCI in the 12-month pre-BAT period (n = 346; 16.3 ± 9.6 min; P<.01). However, primary PCI cases utilizing BAT had mean procedure start to first device/balloon times that were not significantly different than cases who had radial difficulties and went straight from radial to femoral crossover without attempting BAT in both the pre-BAT period (23.6 ± 11.8 min; P=.70) and the BAT period (25.8 ± 13.4 min; P=.54). Importantly, in the 5 cases where BAT was attempted and was unsuccessful, the average procedure start to first device/balloon time (25.2 ± 6.1 min) was similar to the primary PCI cases that went straight from radial to femoral crossover (25.8 ± 13.4 min; P=.56). 

Overall, there were no statistically significant differences in the total procedure times (P=.16) or fluoroscopy times (P=.10) between the groups. However, the primary PCI cases requiring BAT had numerically longer procedure times (57.5 ± 24.5 min) compared with conventional radial access during the same period (48.8 ± 37.2 min) and in the pre-BAT era (47.0 ± 26.1 min) as well as the straight to femoral crossover cases in the BAT era (53.0 ± 14.6 min) and pre-BAT era (54.3 ± 22.4 min). Similarly, the fluoroscopy times of BAT primary PCI cases (14.5 ± 7.1 min) were numerically longer than conventional radial access during the same period (11.9 ± 7.9 min) and  in the pre-BAT era (11.1 ± 7.8 min)  as well as the straight to femoral crossover in the BAT era (10.5 ± 3.0 min) and pre-BAT era (11.9 ± 7.6 min) (Table 2).

In all cases where the area of spasm could be negotiated with a 0.014˝ angioplasty wire, BAT was possible and facilitated catheter advancement through that segment. BAT failed on 6 occasions due to inability to pass a 0.014˝ angioplasty wire in an area of intense spasm or around a radial loop. While on 1 further occasion there was extreme subclavian tortuosity and while BAT allowed the catheter to transverse this area, manipulation of the catheter in the aortic root into the coronary ostium was impossible despite switching to a standard 0.035˝ J-tipped guidewire (Figure 3). Following BAT, 1 patient developed mild forearm hematoma (Bertrand grade 1)14 treated with temporary application of a second TR band that did not delay discharge. There were no other access-site related complications. 


The BAT technique has previously been shown to be effective and safe in a variety of situations including small-caliber radial arteries, radial perforation, radial loops, and resistant radial spasm.12 The BAT technique not only allows the catheter to be tracked through tortuous anatomy, but by maintaining its coaxial arrangement with the artery prevents the “razor” effect of the edge of the guide catheter.12 In addition to preventing discomfort that often occurs when a guide catheter is advanced through an area of arterial spasm, this may also prevent “shaving” the arterial wall, which is a recently recognized complication of guide insertion through a radial in spasm.15 Our institution’s rate of radial access difficulties/spasm of 7.6% is higher than quoted in some studies11 and this is likely due to the high percentage of acute coronary syndromes and primary PCIs at our institution. In these cases, the coronary anatomy is unknown prior to starting; hence, multiple catheter exchanges may be required before the right guide catheter is selected and there is a desire to engage a 6 Fr guide catheter (to preserve options for intracoronary imaging or treated complex anatomy) – both factors that increase the chance of radial spasm. Of the patients presenting with acute coronary syndromes, 25% had a CRUSADE bleeding risk score16 of moderate or higher, emphasizing the benefit of preserving radial access and avoiding femoral puncture. Our rate of radial access difficulties is similar to that found in other large series of acute coronary syndromes and primary PCI patients (5.8%-9.4%).5,7,9 

We found that the BAT technique was successful in a high percentage of cases (91%) who would have otherwise required crossover to femoral access, and routine usage significantly reduced our institution’s crossover to femoral rate (7.6% to 2.5%; P<.01). Interestingly, when BAT was routinely used, the crossover from radial artery access rate (2.5%) was similar to previously documented failure rates from femoral artery access (2.0%-2.8%).5,7,9 There were no significant differences in the procedural times of cases that were completed using conventional radial access, cases requiring BAT to complete, and cases requiring crossover to femoral access to complete. There was a numerical trend toward the use of BAT requiring longer fluoroscopy time (mean, 66 sec; P=.26) than crossing over to femoral access, but there was a numerical trend toward overall procedure times being quicker (mean, 9.4 min) than crossover to femoral artery access (P=.10) despite routine draping and sterilization of the groin in all radial cases at our institution to facilitate crossover to femoral artery access if required.

Study limitations. First, the use of BAT was assessed in a single center with operators highly experienced in the use of radial arterial access. It is possible that operators and institutions with less experience in radial access may have different radial to femoral crossover rates and different success rates with the use of BAT. Nonetheless, our data show that BAT can reduce radial access failure in operators who are experienced in radial PCI. Second, during this study, the default strategy if initial radial access failed was to use the femoral approach. This was due to concerns regarding the prolongation of procedure times if contralateral radial access was also unsuccessful, particularly given the significant proportion of primary PCI in the study. However, attempting contralateral radial access is another acceptable strategy (especially in patients where the perceived benefit of radial access is high) and if successful will also reduce the need for crossover to femoral access. Third, standard left and right coronary catheters rather than single dedicated radial catheters were used during this study and the subsequent catheter exchanges may have increased the rate of spasm. In addition, in 2% of patients, radial access was abandoned early due to impalpable pulses; this may have been reduced if ultrasound-guided radial access had been utilized. Finally, arm angiograms were not routinely performed following BAT, so the impact on the radial arteries is unknown. Also, the effect of BAT usage on radial artery occlusion rates was not investigated; however, BAT did not lead to any clinically significant complications. 

Our study is the first to assess the effect of the routine use of BAT in patients undergoing primary PCI who experience difficulty with radial artery access. Data showing the survival advantage associated with the radial approach are strongest in primary PCI, and this has led to current European guidelines recommending the radial artery as the access site of choice in ST-elevation myocardial infarction for experienced radial operators.17 Hence, any maneuver that reduces the need to crossover from radial to femoral approach is particularly relevant. However, given the time-sensitive nature of primary PCI, it is reassuring that the use of BAT did not delay the time to first device/balloon delivery when compared with straight crossover to femoral access if radial problems occurred (22.6 ± 9.4 min for BAT vs 25.8 ± 13.4 min for femoral crossover; P=.54).

BAT was unsuccessful in 7 cases (5 primary PCIs and 2 acute coronary syndromes). However, it is usually apparent early on whether BAT is going to be successful or not, allowing timely crossover to femoral access if necessary. Six of the BAT failures occurred because the area of tortuosity or spasm could not be traversed with a 0.014˝ angioplasty wire to allow balloon deployment. In our experience, hydrophilic angioplasty wires such as the Whisper guidewire (Abbott Vascular) were better at transversing difficult arterial segments. In 1 failed case, BAT facilitated tracking of the guide catheter through severe subclavian tortuosity, but it was then not possible to engage the coronary ostium (Figure 3). In 2 failed BAT cases, spasm occurred during catheter exchange and it was not possible to wire the segment of extreme spasm. However, there was already a 0.035˝ J-tipped guidewire in the aortic root and this was used to insert a long (120 cm) 5 Fr diagnostic catheter through the 6 Fr guide catheter. The softer tip of the 5 Fr diagnostic catheter played a role similar to an inflated balloon, allowing easy, painless advancement of the guide catheter (Figure 4). 


BAT overcame radial spasm and adverse anatomy, preventing catheter passage in 91% of cases, and routine utilization facilitated a reduction in the requirement for radial to femoral crossover at our institution. Performing BAT rather than crossover to femoral access in cases of radial access difficulty did not increase procedure times or delay the delivery of reperfusion therapy in primary PCI, but allowed 6 Fr guide access without an additional femoral puncture – all important considerations in delivering contemporary evidence-based PCI.


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From the Department of Cardiology, Morriston Hospital, United Kingdom.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted December 20, 2016, provisional acceptance given February 15, 2017, final version accepted March 29, 2017.

Address for correspondence: Dr Daniel Obaid, Consultant Cardiologist, Morriston Cardiac Centre, Swansea SA6 6NL, United Kingdom. Email: daniel.obaid@wales.nhs.uk