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Tips and Tricks for Antegrade Recanalization of Chronic Total Occlusions Using the CrossBoss Catheter

Tak W. Kwan, MD1;  Ravi Diwan, MD1;  Justin A. Ratcliffe, MD1;   Yili Huang, DO1;  Rahul Patri, MD1;  David James, MD1;  Michael Liou, MD1;  Arzhang Fallahi, MD1;  Bruce Young, RCIS2;  Aravinda Nanjundappa, MD3;  Ramesh Daggubati, MD4

Tak W. Kwan, MD1;  Ravi Diwan, MD1;  Justin A. Ratcliffe, MD1;   Yili Huang, DO1;  Rahul Patri, MD1;  David James, MD1;  Michael Liou, MD1;  Arzhang Fallahi, MD1;  Bruce Young, RCIS2;  Aravinda Nanjundappa, MD3;  Ramesh Daggubati, MD4

Abstract: Objectives. To provide new strategies and techniques for the successful recanalization of chronic total occlusions (CTOs) with the sole use of the CrossBoss catheter. In addition, some common CTO scenarios are illustrated in detail. Background. CTOs are one of the most challenging complex coronary lesion subsets to intervene upon. Even with the innovation of specialized catheters, the success rate of antegrade recanalization remains low. Methods. Between June and December 2013, a retrospective analysis of 50 consecutive patients who presented with a planned percutaneous intervention (PCI) of a CTO was performed. In all patients, the CrossBoss catheter was used.  No additional reentry devices were necessary. Procedural success was defined as <20% residual stenosis and TIMI-3 distal blood flow of the treated vessel at the end of the procedure. Results. The majority of the patients were male (72%), with an average age of 68 years. Thirty percent of patients presented with prior CTO-PCI failure. The average fluoroscopy time was 45.9 minutes and the average amount of contrast use was 273.8 mL. No patient suffered a coronary perforation from the CrossBoss catheter. Conclusions. With increased experience using the CrossBoss catheter, the antegrade success rate of CTOs can be improved. Some tips include identifying the likely course of the artery with the aid of retrograde injection, proper guidewire selection and manipulation, and redirecting the CrossBoss catheter if there is substantial deviation from the original path.

J INVASIVE CARDIOL 2015;27(2):E18-E24

Key words: drug-eluting stent, coronary dissection, management, acute coronary syndrome, ST elevation


Chronic total occlusion (CTO) recanalization is a complex and challenging coronary lesion subset in patients undergoing percutaneous coronary intervention (PCI). The prevalence of CTOs is estimated to be about 18% of patients who present for diagnostic coronary angiography. Cases of CTO are typically associated with worse clinical outcomes especially in patients with large ischemia and proximal vessel occlusion.1-4 According to recent studies and meta-analyses, there is significant clinical benefit with improving long-term outcomes in patients undergoing successful CTO stent placement when compared with unsuccessful CTO recanalization.5-7 However, even for the most experienced operators, successful CTO recanalization can often be very challenging. Fortunately, techniques to increase the success rate and to decrease the complication rate associated with recanalization of CTO lesions have evolved rapidly. While retrograde recanalization is gaining more popularity due to an improved success rate in patients with prior failed CTO attempts,8 the equipment and techniques used in retrograde recanalization are highly dependent on the catheterization laboratories and the experience of the operators. Some other important concerns include an extensive learning curve for the retrograde approach. Ultimately, the antegrade approach is the preferred first attempt by most operators. Recently, subintimal reentry techniques including the use of the CrossBoss catheter and Stingray reentry balloon (Boston Scientific Corporation) have resulted in high success rates.9-12 However, the success rate when using the CrossBoss catheter alone has still been quite dismal. In this study, we describe our unique experience with the sole use of the CrossBoss catheter to recanalize CTO lesions. The authors postulate that this approach may actually be associated with higher antegrade recanalization success rates when compared with the prior study.11


Between June 2013 and December 2013, a total of 50 consecutive patients with CTOs were retrospectively analyzed. In all cases, a 7 Fr sheath was inserted into the femoral artery and a 7 Fr guide catheter was employed for antegrade angioplasty.  A 5 Fr sheath was inserted into the right radial artery for retrograde diagnostic catheter injection. In all cases, the CrossBoss catheter was used. No additional reentry devices were necessary. Specifically, the CrossBoss catheter is a metallic, over-the-wire catheter with a 1.0 mm blunt distal tip used to create a 1.0 mm channel. Typically, when the catheter is rotated rapidly using a proximal torque device by digital manipulation, it can advance through the occlusion, either into a subintimal plane or into the true lumen. Procedural success was defined as <20% residual stenosis and TIMI-3 distal blood flow of the treated vessel at the end of the procedure. This study also presents some common CTO scenarios in detail, illustrating various tips and tricks.  


Patient demographics are displayed in Table 1. In this cohort, 30% of patients had a prior failed CTO-PCI attempt using various other crossing techniques. Table 2 showed the procedural characteristics and outcomes. Five patients had an unsuccessful initial attempt, with the procedure terminated in order to limit excessive contrast volume use and fluoroscopy time. Three out of 5 patients (60%) were reattempted at a later date and were successfully recanalized. No patient suffered a coronary perforation from the CrossBoss catheter. All patients received drug-eluting stents. Examples of successful cases are discussed below.

Case #1: True to true lumen reentry with the CrossBoss catheter. A 60-year-old woman presented with a history of prior coronary artery bypass graft (CABG) surgery. Initial angiogram revealed an occluded left internal mammary artery (LIMA) to left anterior descending (LAD) artery and a patent saphenous venous graft (SVG) to diagonal, which provided retrograde filling to the LAD (Figure 1A). PCI of the native proximal LAD lesion was planned in this patient. Visualizing the microchannel with a nipple in the proximal cap, we advanced the Confianza Pro12 guidewire (Abbott Laboratories) to the proximal cap and parked the CrossBoss catheter just at the nipple before spinning the CrossBoss down (Figure 1B). As illustrated in this case study, true-to-true lumen can often be connected (Figure 1C) and subintimal dissection can often be avoided. PCI was then completed successfully (Figure 1D).

Case #2: Subintimal to true lumen reentry by keeping a proper path. A 68-year-old man with a history of hypertension presented with exertional angina. Diagnostic cardiac catheterization revealed a totally occluded LAD with retrograde filling from the right coronary artery (RCA) (Figure 2A). In this CTO without a visible nipple, we used a stiff guidewire, the Pilot 200 (Abbott Laboratories), to enter proximally into the subintimal space, and then spun down the CrossBoss catheter after the guidewire had been pulled back into the device. The CrossBoss catheter entered the vessel in the subintimal space (Figure 2B). We attempted to keep the path of the CrossBoss catheter as tightly in line with the true lumen as possible. At times, it may be necessary to redirect the guidewire and the CrossBoss catheter to another path to be as close to the true lumen as possible. Frequently, the CrossBoss catheter will enter into the true lumen just by spinning the catheter forward (Figure 2C). PCI of the occluded vessel was then completed (Figure 2D).

Case #3: Subintimal to subintimal lumen reentry. A 67-year-old man was referred for PCI of a totally occluded LAD with retrograde filling from the RCA (Figure 3A). The retrograde approach was initially discussed, but a first attempt at an antegrade approached was decided upon. We used a Pilot 200 guidewire to enter the subintimal space. The CrossBoss catheter was again spun down, but stayed in the subintimal space (Figures 3B and 3C). By using the Pilot 200 guidewire, we advanced the guidewire back into the true lumen (Figure 3D). PCI was then completed (Figure 3E).

Case #4: In-stent chronic total occlusion. A 58-year-old man presented with a history of previous PCI of the RCA and known occlusion of the stent site for more than 10 years (Figure 4A). He presented with a large reversible defect and crescendo angina. Reattempt of the totally occluded RCA was planned. In patients presenting with in-stent CTOs, we believe that an antegrade approach with the CrossBoss catheter should be the first choice. We used a stiff Pilot 200 guidewire to enter the true lumen inside the stent (Figure 4B), and the CrossBoss catheter was then employed to spin down through the in-stent lumen. The CrossBoss catheter stayed inside the lumen, but went into the subintimal space distally because of a gap in between the stents (Figure 4C). We pulled back the CrossBoss catheter and with the aid of the stiff guidewire, it was redirected back into the in-stent lumen (Figure 4D). PCI was then completed (Figure 4E).

Case #5: Ostial flush occlusion with a “scratch-wire” technique. A 55-year-old female presented with a flush occlusion of the ostial LAD (Figure 5A) and retrograde filling from the RCA. The retrograde approach was considered, but an antegrade approach was attempted first. In this case of an ostial flush occlusion, we performed a “scratch-wire” technique by using a stiff Confianza Pro12 guidewire to enter the subintimal space (Figure 5B). We first performed multiple contrast injections to identify the likely path of the occluded vessel. After carefully confirming guidewire placement in the subintimal space, the CrossBoss catheter was advanced and the guidewire was pulled back. Careful inspection with contrast injections to detect any perforation must be performed before the CrossBoss is spun forward. Once confirmed, the CrossBoss catheter can be utilized. If the CrossBoss catheter is able to spin forward smoothly, it is correctly situated in either the true lumen or in the subintimal space. If there is difficulty in spinning the catheter, the operator should seek another entry point, as the CrossBoss catheter may have hit calcium or may be in danger of going outside of the vessel. Once the CrossBoss catheter is spun forward without difficulty, we attempted to keep the path as close as possible to the true lumen. The guidewire then reentered the true lumen without much difficulty (Figure 5C). PCI was completed (Figure 5D).

Case #6: Spinning from the RCA ostium using a bare CrossBoss catheter without guidewire. A 60-year-old man with previous CABG presented for RCA-PCI. The RCA was totally occluded from the ostium (Figure 6A). The retrograde approach was a viable option, but only after an antegrade approach was attempted first. In this patient with a flush occlusion from the RCA ostium and without a clearly identifiable path, we spun down the CrossBoss catheter from the ostium without the usual accompaniment of a stiff guidewire. Oftentimes, as seen here, the CrossBoss catheter will find the path itself (Figure 6B) and a Pilot 200 guidewire can be advanced (Figure 6C). PCI was then performed (Figure 6D).

Case #7: Extra support from an extension catheter to advance the CrossBoss catheter. A 58-year-old male patient presented with a CTO of the LCX. The case was further complicated by a very acute angle between the left main (LM) artery and the LCX (Figure 7A). Frequently, the CrossBoss catheter is unable to make the necessary turn when approaching such an acute angle. Subsequently, we used an extension catheter, and with adequate back-up support, the CrossBoss catheter was able to make the acute turn into the LCX (Figure 7B). After spinning down the CrossBoss catheter, we inserted a Pilot 200 guidewire into the true lumen (Figure 7C). Double stenting technique using DK crush stenting was then completed (Figure 7D). 


In recent years, there has been growing interest in the treatment of CTOs due to significant advances in the knowledge of pathology, equipment, and technical skill.1-4 Traditionally, the antegrade approach is the preferred method for CTO recanalization due to ease of procedure and shorter procedural times.14 However, although the retrograde approach is associated with a higher learning curve and possible increase in complications (eg, epicardial collateral perforation, longer fluoroscopy time and dose, and extensive equipment that many cardiac catheterization laboratories do not have readily available), this technique is gaining momentum as it achieves a higher success rate in previously failed CTO cases.-8 With the recent development of the CrossBoss catheter and Stingray balloon systems, a high success rate for antegrade CTO recanalization can be achieved.11 The CrossBoss catheter is a simple device with a quick and uncomplicated set-up that can be used in any catheterization laboratory without a steep learning curve for experienced interventionalists. We believe that previously reported success rates of 30% for the CrossBoss catheter alone11 can be greatly improved. With increased experience in using the CrossBoss catheter, the antegrade success rate can be increased, and the retrograde approach can be reserved for a smaller subset of patients.

It is important for interventionalists to have a working knowledge of helpful techniques for the treatment of CTOs. There are a few important steps in performing the CrossBoss catheter antegrade approach successfully: (1) identification of the likely course of the artery with the aid of retrograde injection; (2) proper guidewire selection and manipulation; and (3) redirection of the CrossBoss catheter if there is substantial deviation from the original path. This case series successfully illustrates some common scenarios of CTO and defines how to improve successful antegrade recanalization by using the CrossBoss catheter alone.

Importance of choosing the path and the aid of retrograde injection. We believe it is important to define a likely course of the artery using antegrade and retrograde injections. The guidewire is carefully advanced toward the path and into the direction of the retrograde collaterals. Although the preferred destination is the true lumen, the subintimal space is acceptable as well. Once the guidewire is in the lumen or subintimal space, the CrossBoss catheter may be advanced up to the point of the guidewire. Caution must be used so as to not advance the CrossBoss catheter distal to the guidewire. After the guidewire is withdrawn back into the catheter, the CrossBoss catheter can be spun down along the lumen or subintimal space. While the CrossBoss catheter is in the subintimal space, repeated vigorous antegrade test injections may propagate the enlargement of the false lumen and obscure visualization of the distal vessel. Therefore, it is important to perform retrograde injections to keep the correct path once the CrossBoss catheter is in the false lumen. From previous experience, we always try to keep the CrossBoss catheter as close to the true lumen as possible. The CrossBoss catheter can either reenter into the true lumen by itself, or with the aid of a stiff guidewire. Either way, reentry can be performed without much difficulty. In addition, we prefer to use 300 cm guidewires for all of these cases, as the CrossBoss catheter is an over-the-wire catheter. 

Importance of guidewire selection and manipulation. The wiring technique is crucial to success in CTO-PCI.  Stiff guidewire manipulation is a very important step. The Pilot200 or Confianza Pro12 were the guidewires of choice for use with the CrossBoss catheter. The combination of the CrossBoss catheter and the Confianza Pro12 might increase the penetrating power of the guidewire; therefore, this combination should be used with caution and be reserved for extremely difficult lesions, especially those containing a thick, hard proximal fibrous cap.  The high success rate seen in this study is driven by the careful management of the guidewire and the CrossBoss catheter in the subintimal plane. Realizing the path of the subintimal plane and keeping it tight to the true lumen is definitely one of the main ways to achieve a successful result.

Importance of CrossBoss catheter manipulation. CrossBoss catheter manipulation is also very important; it should be focused in one direction with a rapid spinning of fingers. Forward force should be gentle, with adequate guiding support. Occasionally, an extension catheter may be required to give extra back-up support in order for the CrossBoss catheter to advance over a bend. Occasionally, it was necessary to dilate the proximal lesion with a small balloon in order for the CrossBoss catheter to move forward. If the CrossBoss catheter is unable to be spun forward, we pull the catheter back and find another path. After pulling the CrossBoss catheter back slightly proximally, it can be redirected into a path that is closer to the true lumen. With the help of stiff guidewires, the success rate of reentry into the true lumen is very high. We discovered that as long as the CrossBoss path is kept close to the true lumen, with frequent redirection of the stiff guidewire, it will reenter the true lumen successfully. The advantage of not using a reentry balloon is avoiding the sharp guidewire puncture and its entrance into the diseased distal lumen, which will increase perforation risk. 

Importance of knowing when to stop the procedure. Complications can develop during prolonged procedures.15 We generally discontinue the procedure when the fluoroscopic time has reached >60 minutes and contrast volume exceeds 350 mL. Patients can simply return for a second visit to be successfully recanalized since we have already identified the path of the CTO and have also created a lumen from the CrossBoss catheter during the initial attempt.

Study limitations. Coronary perforation is a potentially catastrophic complication of all CTO recanalization techniques.16 Perforations can occur if the stiff guidewire punctures the vessel and the CrossBoss catheter is followed through. Perforation can also occur if the CrossBoss catheter spins into a small vessel. However, by using retrograde injection and obtaining multiple views of the likely course, along with careful guidewire manipulation, the use of the CrossBoss catheter appears to be rather safe. Interestingly, this catheter tends to stay in the subintimal space; it does not often spin outside the vessel wall. There were no perforations seen in this case series. Another concern is the high restenosis rate in all CTO reentry methods.13 With the present techniques, the CrossBoss catheter often enters into the true lumen without a long dissection plane. However, the restenosis rate will still need to be further addressed in future studies.


With increased experience in using the CrossBoss catheter, the antegrade success rate of CTOs can be improved. The tips and tricks for the CrossBoss catheter presented here will help interventionalists maximize procedural time, minimize the learning curve, and increase procedural success without compromising safety. 

Acknowledgments. The authors would like to recognize Samin K. Sharma, MD, from the Mount Sinai Hospital, New York, New York, for his contributions to this study.


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From the 1Beth Israel Medical Center, New York, New York; 2Boston Scientific Corporation, Natick, Massachusetts; 3West Virginia University, Charleston, West Virginia; and 4Brody School of Medicine at East Carolina University, Greenville, North Carolina.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Bruce Young, RCIS, is a clinical specialist for Boston Scientific. The remaining authors report no conflicts of interest regarding the content herein.

Manuscript submitted April 28, 2014, provisional acceptance given May 13, 2014, final acceptance given June 23, 2014.

Address for correspondence: Tak W. Kwan, MD, Senior Associate Director of Cardiac Catheterization Laboratory and Interventional Cardiology, Beth Israel Medical Center, 139 Centre St, Rm 307, New York, NY 10013. Email: