Specialty Microcatheters to Facilitate Antegrade Crossing for CTO Revascularization

Introduction

Despite advances in wire and stent technology, chronic total occlusions (CTOs) remain a difficult lesion subset to treat. CTOs are present in about 20% of patients undergoing cardiac catheterization; however, only a small percentage are offered percutaneous treatment.^1,2 There are several reasons for this. Time and resource constraints, complications risk, and variations in technical expertise are some of the reasons for inconsistent attempt rates. The current hybrid algorithm approach to CTO percutaneous coronary intervention (PCI) uses a combination of antegrade and retrograde techniques to facilitate wire crossing and procedural success.³ In the early stages of adopting this approach, some operators may use an antegrade-only approach.4 The use of specialty catheters and wires may facilitate engagement and crossing of the proximal cap. We present two case examples using the SuperCross microcatheters (Vascular Solutions) to perform CTO revascularization via an antegrade approach.

Case #1

This is a 62-year-old male with recent admission to another outside hospital with positive troponins, and cardiac catheterization revealing a CTO of the circumflex artery and right coronary artery (RCA). He had ventricular tachycardia and had a subsequent revascularization at the hospital twice which was unsuccessful. He was then referred to our institution for bypass. Given that there was no involvement of the left anterior descending coronary artery (LAD), he was referred by surgery for possible CTO revascularization. Repeat angiography revealed a CTO of the circumflex artery (left-left collaterals) with a CTO of the RCA as well, with what appeared to be filling via right-to-right collaterals (Figures 1-2). Based on the angiogram and his clinical presentation, it was decided to fix the circumflex CTO first.

The right radial was accessed with a 6/7 GlideSheath Slender (Terumo) and the left radial was accessed with a 6 French sheath.  A Q 3.5 guide catheter (Boston Scientific) was used to engage the left coronary system and an Amplatz right (AR) mod guide catheter (Cordis) was used to engage the RCA in order to perform dual angiography.  

The left main was calcified and bifurcated into the LAD and circumflex artery. The LAD was patent with mild angiographic disease and no focal obstructions. It gave rise to a diagonal and there was some evidence of left-to-left collaterals. The circumflex artery was 100% occluded after what appeared to be a high atrioventricular (AV) groove. It was a short occlusion and then reconstituted into obtuse marginal branches (OM)1 and a large OM2. There is calcification noted in the occlusion. The RCA was a large-caliber artery. It was occluded distally at the crux, and had some late right-to-right collaterals.

Heparin was administered, and using a Turnpike Gold catheter (Vascular Solutions) and a Runthrough wire (Terumo), we got into the circumflex and then exchanged out for a Gaia guidewire (Asahi Intecc) to penetrate the proximal cap. The Turnpike Gold catheter, unfortunately at this point, was downward and therefore, did not allow engagement of the proximal cap (Figure 3). The catheter was changed for a SuperCross 90-degree catheter (Vascular Solutions), which pointed the wire up towards the blunt cap of the CTO and away from the bifurcation (Figure 4). We then used the Gaia wire to penetrate the proximal cap and gain some purchase. We advanced the 90-degree SuperCross catheter, but it  would not penetrate the cap. We were able to get the guidewire to gain some more purchase and then switched out for the Turnpike Gold catheter. Using the Turnpike Gold in a clockwise manner permitted advancement into the proximal cap and advancement of the guidewire distally. Once we confirmed it was luminal, we tried to advance the Turnpike Gold to switch out the wire, but we could not advance completely without the guide catheter backing out. well as the calcification of the vessel. We switched the wire out to a Pilot 200 wire (Abbott Vascular) and were able to wire both branches, OM1 and OM2, to confirm there was no subintimal wire placement. Given that OM2 was a larger branch, we placed the wire distally, confirmed that we were luminal (Figure 5), and then, in a counter-clockwise manner, removed the Turnpike Gold catheter. A 0.9 mm laser (Spectranetics) was used to perform laser athrectomy at the setting of 40/60 initially, then at 60/80, as multiple passes were made to create a pilot channel (Figure 6). A 2.0 x 15 mm AngioSculpt balloon (Spectranetics) was successfully advanced and predilated the lesion (Figure 7). After significant predilation at 10 atmospheres for 1 minute, we were able to wire a Runthrough wire into the OM1. We ballooned with a 2.25 x 20 mm balloon and switched out the Pilot wire for a second Runthrough wire (Figure 8). We advanced a 2.5 x 26 mm Resolute stent (Medtronic) favoring the OM2, which was a larger branch, and inflated at nominal pressure. We removed the Runthrough wire from the OM1 and using the Turnpike Gold as support, rewired the OM with a Sion wire (Asahi Intecc). We ballooned with a 2.0 x 20 mm balloon in the OM1 and in the ostium, and predilated the OM2 circumflex stent with a 2.5 mm Quantum balloon (Boston Scientific). A low-pressure inflation of the OM1 was performed with a 2.0 mm balloon at 4 atmospheres, and after intracoronary nitroglycerin (NTG), final angiography revealed TIMI-3 flow without dissection, embolization, or perforation, with an excellent angiographic result (Figure 9). The patient was staged for the RCA CTO 4 weeks later and had successful PCI using a SuperCross catheter and a Twin-Pass catheter (Vascular Solutions) to complete the procedure.

Case #2

A 70-year-old male with a history of coronary artery bypass graft surgery (CABG) x 3 in 2000 and an implantable cardioverter defibrillator (ICD) (for inducible ventricular tachycardia [VT] in 2006) presented with chest pain and precordial ST depression and positive troponins. He was taken to the lab urgently for ongoing chest pain and a left heart catheterization was performed, revealing a patent left internal mammary artery-left anterior descending coronary artery (LIMA-LAD), occluded saphenous vein graft-right coronary artery (SVG-RCA) (with collateral filling of the native RCA via left-to-right collaterals) and an occluded SVG to the obtuse marginal (OM) (Figures 10-11). The SVG-OM was the culprit based on the angiogram, electrocardiogram (EKG), and clinical presentation. 

It was decided to revascularize the native OM instead of an occluded 16-year old graft. Given the patient’s height (6 feet, 9 inches), it was decided to access the right brachial for secondary access (guide length can be an issue from the radial). The femoral sheath was upsized to an 8 French with an Extra Backup (EBU) 3.75 guide (Medtronic). From the brachial approach, an Amplatz left (AL) 1 was used to engage the SVG-OM, and a wire passed distally to mark and control the distal vessel (Figure 12). The proximal cap was defined, but the branch came off at an angle. Initial attempts were made to wire with a Turnpike catheter (Vascular Solutions), and Fielder XT (Abbott Vascular) and Pilot wire (Abbott Vascular). The angle made it difficult to engage the cap (Figure 13) and a SuperCross 120 catheter allowed us to engage with a Fielder XT and maintain the “CTO bend” on the wire (Figure 14). The wire was “knuckled” and advanced through the occlusion into the true distal lumen (Figures 15-16). Excimer laser, intravascular ultrasound (IVUS), and stenting were performed on the native vessel with placement of a 2.5 x 38 mm and a 3.0 x 16 mm Synergy stent (Boston Scientific) (Figure 17). There was a wire perforation noted of no hemodynamic or clinical consequence. The patient was discharged home the following morning.

Discussion

There are several factors that favor an antegrade-only approach to CTO revascularization (for those not adopting the hybrid algorithm): 

1) Well-visualized proximal cap;

2) Presence of a microchannel;

3) Minimal calcification;

4) Occlusion <20 mm;

5) No angulation >45 degrees; and 

6) A good distal target.⁴

In addition to wire selection, microcatheter support can enhance “pushability” and facilitate lesion crossing. There are several microcatheters available and the most commonly used ones in the United States include the Corsair (Asahi Intecc), Finecross (Terumo), and Turnpike (Vascular Solutions). These are straight-tip catheters and therefore, may not provide the best approach for an angled proximal cap.

The SuperCross catheters are a series of microcatheters used for guidewire support and directional wiring. In addition, they can be utilized for subselective delivery of diagnostic and therapeutic agents. The coronary catheters are available in straight, flexible, and angled versions (Figures 18-19). The angled-tip catheters are available in a 45, 90, 120 and 90 XT (extended degree tip for secure cannulation). The inner layer is PTFE and the outer layer is hydrophilic.  They have a 0.71 mm outer diameter (OD) and 0.43 mm inner diameter (ID), and are 6 French compatible. We have used these catheters to access side branches, as wire support for an angulated left circumflex off the left main, and, as in the above cases, to engage a difficult proximal cap. Once we have gained purchase into the CTO, the microcatheter is usually changed to a Corsair, Turnpike, or Finecross to navigate the remainder of the occlusion. When the wire is able to cross, but the microcatheter cannot follow, a catheter such as the Tornus (Asahi Intecc) or Turnpike Gold may be able to advance through the occlusion (other options, if available, include laser atherectomy or exchanging the wire for rotational atherectomy). A full discussion about antegrade crossing of CTOs is beyond the scope of this article. For more information, visit ctofundamentals.org.

References

1. Fefer P, Knudtson ML, Cheema AN, Galbraith PD, Osherov AB, Yalonetsky S, et al. Current perspectives on coronary chronic total occlusions: The Canadian Multicenter Chronic Total Occlusions Registry. J Am Coll Cardiol. 2012; 59:991-997.
2. Grantham JA, Marso SP, Spertus J, House J, Holmes DR Jr., Rutherford BD. Chronic total occlusion angioplasty in the United States. JACC Cardiovasc Interv. 2009; 2: 479–486. 
3. Brilakis ES, Grantham JA, Rinfret S, Wyman RM, Burke MN, Karmpaliotis D, et al. A percutaneous treatment algorithm for crossing coronary chronic total occlusions. JACC Cardiovasc Interv. 2012; 5: 367– 379.
4. Rinfret S, Joyal D, Spratt JC, Buller CE. Chronic total occlusion percutaneous coronary intervention case selection and techniques for the antegrade-only operator. Catheter Cardiovasc Interv. 2015 Feb 15; 85(3): 408-415. 

Disclosures: Orlando Marrero reports he is a consultant for Boston Scientific. 

Dr. Zaheed Tai reports the following: Terumo (proctor for transradial course), Spectranetics (proctor for laser course, speaker, advisory board member), and Boston Scientific (CTO proctor).

Orlando Marrero, RCIS, MBA, can be contacted at orlm8597@icloud.com. 

Dr. Zaheed Tai can be contacted at zaheedtai@gmail.com.