Chronic Total Occlusions in the Coronary Vasculature

Chronic total occlusions (CTO) in the coronary circulation present a major challenge for the interventional cardiologist. The past few years have witnessed the development of novel techniques and devices to successfully revascularize this difficult subset of coronary artery disease. Studies have concluded that CTOs can be found in one-fifth to one-third of patients undergoing diagnostic cardiac catheterization. Frequently, these patients have been referred for coronary angiography due to clinical symptoms or abnormal results of stress test demonstrating ischemia. Increasingly, data from numerous studies suggest that, in the appropriate patient subset, successful recanalization confers a significant survival advantage.^1–6 Our group has been treating CTOs for 28 years. At our cardiac cath lab, we successfully revascularize about 100–150 CTOs each year, with excellent results. Some lesions have been estimated to date back as far as 42 years. As a radial-first lab, we often approach coronary CTOs from the radial access. Herein, we will discuss some important aspects of percutaneous coronary intervention (PCI) for CTOs and present three cases performed at our center.

Benefits of CTO-PCI

CTO-PCI has the potential to offer patients several benefits, including symptom relief, improvement in left ventricular function, better long-term survival, reduced predisposition to arrhythmic events and improved tolerance of contralateral coronary occlusion.

Patient Selection

Before attempting to revascularize CTOs, careful consideration must be given to individual risks and benefits for each patient. Indications for opening CTOs include relief of angina, evidence of ischemia in asymptomatic patients, improved left ventricular function and improved long-term survival. Both clinical as well as angiographic features should be carefully reviewed. From a clinical point of view, age, symptom severity, associated comorbidities (like diabetes mellitus and renal disease), and overall functional status are major determinants of treatment strategy. Angiographically, the extent and complexity of coronary artery disease, likelihood for complete revascularization, and the presence and degree of valvular heart disease and left ventricular dysfunction are all important factors. Some angiographic features are associated with a lower likelihood of success, such as the presence of a blunt or a flush occlusion, the presence of the occlusion at a side branch, small vessel size, marked tortuosity, heavy calcification and the presence of bridging collaterals. Longer lesions have worse chance of success than shorter occlusions.

Access

After all preparatory measures have been completed and the patient has been identified as an individual who would potentially benefit from the procedure, determination of catheter access site and the guiding catheter size are of initial importance. Early preparation and anticipation will provide the operator with a maximum number of options in the face of the unexpected. Hence, it is recommended that an 8 French (F) femoral sheath and a contralateral 5 or 6F arterial sheath should initially be used before anticoagulation. The sheath should be large enough to provide for multiple wires, catheters, balloons, and devices. Dual injection (simultaneous contralateral injection) should be performed to evaluate the length of the lesion, to use as a landmark for the target of the guidewire, and to use as a route for the retrograde approach.

Guidewires

Two groups of wires are usually used for the CTOs, polymer-coated and coil wires. Coil wires are non-hydrophilic and are characterized by better tactile feel and a more controlled torque response when compared with hydrophilic wires. They are less likely to dissect the vessel, but at a cost of more resistance within the lesion, reducing the chances of successful CTO traversal. To compensate, some uncoated, spring-coil wires have a tapered-tip design that offers more penetrating power to the tip. These include the following families of wires: Cross-It (tip diameter 0.010”/0.25 mm) (Abbott Vascular, Redwood City, CA); Persuader 9 g (tip diameter 0.011”/0.28 mm) (Medtronic, Inc., Minneapolis, MN); Confianza (tip diameter 0.009”/0.23 mm) and Confianza Pro 8-20 (tip diameter 0.008”/0.20 mm) (Asahi Intecc, Nagoya, Japan). Alternatively, some guidewires may have greater tip stiffness, rather than sharpness, to increase their penetration capabilities. These include Magic S 9 g (tip diameter 0.0128”/0.32 mm) and Magic Ex 18 g (tip diameter 0.0128”/0.30 mm) (Japan Lifeline, Tokyo, Japan). Polymer-coated wires have a hydrophilic coating that markedly lowers friction, helping the wire to move easily through the vessel lumen. This feature may also increase the risk of advancing the wire into subintimal planes and creating a false lumen, long dissections or perforations. Polymer-coated wires are also more likely to lose their tip-shape than uncoated wires. As a result, many operators use polymer-coated wires when the occlusion has been engaged, but progress can no longer be made with an uncoated wire. There are two different groups of hydrophilic wires; the first group has hydrophilic coating only on the tip and includes the Whisper MS and LS (Abbott Vascular), Pilot 50 (Abbott Vascular), Fielder, Fielder FC, Fielder XT (Asahi Intecc), Shinobi and Shinobi Plus (Cordis Corporation, Miami, FL). The second group is coated along both the shaft and the tip, and includes the Pilot 150/200 (Abbott Vascular), Choice PT/PT2, PT Graphix/ Graphix P2 (Boston Scientific Corp., Natick, MA) and Runthrough Hypercoat (Terumo Medical Corp., Somerset, NJ). Recently, we have used a new class of wires by Medtronic, the Provia wires, designed for the most difficult lesions. This group of wires provides overall “best in class” torque and lesion penetration performance due to the following features:

• High torque core process: Eliminates inherit wire bias and stress to maximize torque response. • Grind design: Increased length of distal tapers to optimize torque transmission and control. • Co-axial coil design: Core wire is centered all the way to distal tip for improved steering. • Rounded tip design: Improves torque and helps eliminate “whipping.” • Improved coil pitch: Tighter design improves steering and control in confined spaces.

Many operators go from the light wire to the heavy, starting with a soft tip, then change to a harder and stiffer wire, if the lighter and softer wires do not work. For occlusions that are less than 6 months old, an intermediate wire will usually work. For harder lesions, older than 6 months, wires with harder tips will often be needed.

Microcatheters/Over-the-Wire

The wire should always be used with an over-the-wire (OTW) balloon or a microcatheter in order to ease torque in the tip response, preventing flexion, kinking, prolapsing of the guidewire, and improving penetration ability. OTW devices also allow modification of the guidewire curve, guidewire reshaping, and exchanging to another guidewire. Once the stiff wire has crossed the CTO and reached the distal true lumen, using OTW devices also allows an exchange of a stiff wire to a floppy wire, minimizing the risk of distal wire perforation or dissection. Microcatheters may provide a better tip flexibility than OTW balloons and may provide better wire manipulation, due to their larger inner lumen, which reduces friction. Microcatheters also have the advantage of a radiopaque marker at the catheter tip, which has a flat end. Both of these characteristics help to avoid advancing too far into the lesion, something that occurs frequently with use of an OTW balloon. The choice between an OTW balloon catheter and a dedicated microcatheter depends on the features and CTO complexity, as well as operator preference. Dedicated microcatheters (below) are available that have the advantage of providing specific characteristics in their use. Tornus (Asahi Intecc). The Tornus crossing microcatheter has been developed to penetrate severe and hard lesions with greater flexibility and torquability, offering a rotational burrowing and advancement manually, maneuvered by counter-clockwise rotation. The catheter consists of eight individual stainless steel wires (0.007” diameter) spirally bound together to form a tapered microcatheter. Corsair (Asahi Intecc). The Corsair is a septal dilator catheter used for the retrograde approach. This is a microcatheter dedicated to selective engagement of the collateral channel. It consists of a tapered tip and screw head structure, which reinforces torque transmission for the guidewire and creates better back-up support for CTO penetration. The Corsair possesses a soft tip made of tungsten powder and a 0.8 platinum marker coil 5 mm from the tip, which makes it easy to identify the distal tip under fluoroscopy. CPS Venture wire control catheter (Velocimed/St. Jude Medical, Minnetonka, MN). The Venture catheter is a deflatable tip catheter that provides directional steering and focused pushabilty for efficient wire placement. The deflatable 8 mm radio-opaque tip can form any angle from 0 to 90 degrees in a single plane, allowing precise placement of the wire within the lesion.

Anchoring Balloon

The balloon anchoring technique utilizes a standard compliant OTW balloon. The wire and balloon are initially advanced together. Once the balloon is adequately placed proximal to the lesion, the balloon is inflated. The balloon then serves as an anchor providing support for the wire and the guide. With this added support, the wire can be more forcefully directed at the CTO. Another variation of this technique involves inflation of the balloon in a side branch, such as the conus or the acute marginal branch. This has the obvious advantage of allowing for contrast injection and free, unobstructed access to the CTO. By applying gentle withdrawal pressure to the balloon and forward pressure on the guide, the support balloon anchoring technique allows for better coaxial positioning and deeper seating of the guide in the target vessel. In general, although this procedure can be performed with a 5F catheter, a 7 or 8F catheter is usually preferred. We have worked on prototypes that may be more effective for this technique, where the balloon has a shorter tip, as well as a much shorter length (less than 2 in tip length and 5 mm in length). In a silastic tube model, we have shown that such a prototype balloon is more effective as a support system for crossing a ‘putty-type’ total occlusion compared to conventional balloons.7 The balloon size can be dilated to 6 mm and is able to be used in multiple diameter-size silastic tube models.

Crossing Techniques

Parallel Wire Technique. With this technique, if the guidewire enters the wrong plane, it can be left in place as a marker of the incorrect plane. A second wire, supported by an OTW balloon, probes alongside the first in an effort to find the true lumen. A variation of this method is the ‘seesaw’ wiring technique, where both are supported by an OTW balloon. This enables alternate use of the wires, which easily alternate their roles as marking and advancing wires. The effectiveness of the parallel wire technique is the following: (1) The first wire can occlude the entry site of the false lumen and can be used as a landmark (with the potential to reduce the contrast; (2) The first wire can modify the arterial geometry, resulting in a reduction of the resistance for the second wire passage; and (3) The second wire can find the true lumen easier than the first wire, using the first wire as a landmark. In this technique, tapered-tip wires are considered more adequate for the second wire than conventional wires. Tapered-tip wires can create a channel different from the channel created by the first wire, owing to stiff and tapered tips. The STAR technique. The Sub-intimal Tracking and Re-entry, or the STAR technique, aims at creating a subintimal dissection with distal re-entry. A 0.014” hydrophilic wire with a J configuration is utilized. The hydrophilic wire is pushed through the subintimal dissection plane. When pushed distal to the occlusion, the J tip is directed towards the true lumen, attempting to re-enter. It is critical with this technique to maintain a small J loop at the tip of the wire. Because of its proclivity to shear side branches, the STAR technique is best suited for conduit-style vessels with minimal branching structure, such as the right coronary artery (RCA) or obtuse marginal artery branches. This technique is reserved for refractory CTOs with strong indications for revascularization and should only be performed by operators experienced in this technique. Retrograde Wire Technique. When antegrade crossing of a CTO fails, the retrograde approach may be considered. The retrograde technique uses collateral channels from the opposite coronary artery to approach the CTO retrogradely with a wire and/or balloon. The distal side of the CTO fibrous cap is often less resistant than the proximal cap, and once a wire is engaged within the lesion, it is frequently easier to traverse than with a traditional antegrade approach, particularly when antegrade branches to the proximal cap exist. The retrograde approach should be considered a primary strategy if the procedure is a second attempt after previous failed attempt, if the CTO has several unfavorable anatomical features, if the CTO is relatively long (> 15–20 mm), if the distal vessels receives visible collaterals, and the donor vessel is healthy. Anatomical features that are more suitable for a retrograde approach are, for example, true ostial left descending artery occlusions without a stump, or medial RCA occlusion with a large marginal arising at the site of the CTO.

Case Reports

Case #1: Introducing Medtronic wires and demonstrating Impella use. This case involves a 59-year-old male with a history of a large anterior wall myocardial infarction in 1988. On September 30, 2009, he had a stent placed in the circumflex coronary artery. There was stenosis of the RCA with patent previous stents. The left anterior descending artery (LAD) was chronically occluded in the distal segment. His left ventricular function was diminished with an ejection fraction of 35% and anterior hypokinesia was noted. A month later, the patient presented with acute congestive heart failure (CHF). He had a new apical thrombus. After anticoagulation was started, he had an episode of amaurosis fugax. This responded to enoxaparin and warfarin therapy. The patient presented 6 months later due to CHF exacerbation. His ejection fraction deteriorated to about 15%. An automatic implantable cardioverter-defibrillator (AICD) and synchronized pacemaker were placed. We considered recanalizing the presumed occlusion of the circumflex artery. On May 4, 2010, we attempted to recanalize the patient’s circumflex artery; however, just the presence of the guiding catheter in the left main artery resulted in hypotension and near respiratory arrest. He was brought back to the catheterization laboratory the next day, and, because of acute exacerbation of his CHF, we placed the Impella device (Abiomed Inc., Danvers, Mass.) via the patient’s left groin. He had significant disease in the proximal LAD prior to the total occlusion, which was interrogated with intravascular ultrasound. There was 80% stenosis of the proximal LAD. A Cougar wire (Medtronic) was placed in the LAD, followed by a 3.5 x 24-mm Endeavor stent (Medtronic), which was postdilated with a 4 x 15-mm high-pressure balloon. An extra back-up guide (Medtronic) was placed and a 3 x 10-mm anchoring balloon was inflated in the proximal portion of the circumflex artery. We used the Provia 6 (Medtronic) and then the Provia 9 wires. We then exchanged for a Transit catheter (Cordis) and distally went in further with a Gold wire (Terumo Medical Corp.). The Gold wire was then exchanged for a Fielder XT (Asahi Intecc/Abbott Vascular) and a 1.5 x 6-mm balloon was placed. We could see that we were under struts from the previously placed stents. We then were able to perform multiple balloon inflations, first with a 1.5 x 5-mm and then an AngioScore balloon (Angioscore, Inc., Fremont, CA). We placed a 3.5 x 18-mm, a 3.5 x 30-mm, and several other Endeavor stents. By the end of the procedure, the occlusion went from 100% to 0%. This case demonstrates the ability to use the Impella device to treat high-risk chronic total occlusions and introduces several extremely torqueable and maneuverable wires by Medtronic. Case #2: Use of the radial approach. A 70-year-old gentleman was told his right coronary artery (RCA) had been 100% occluded for 6 years. He presented with continued angina and ischemia, not only in the inferior territory, but also the lateral territory. His risk factors for coronary disease include hypertension, hyperlipidemia and known chronic occlusion of his RCA for the last 5 to 6 years. Angiography showed that a total occlusion of the obtuse marginal was present; multiple injections with several catheters were unable to visualize the RCA. There was no antegrade filling of the RCA with multiple catheters. Aortic root injection did not allow visualization of the origin of the vessel. By observing collaterals, it was clear that the RCA was 100% occluded. The patient was enrolled in the FAST CTO study (Facilitated Antegrade Steering Technique in Chronic Total Occlusions, BridgePoint Medical) to treat the circumflex artery CTO. With difficulty torqueing the catheter, a long, 65-cm Arrow 7 F sheath (Arrow International, Cleveland, OH) was placed and we used an EBU (Medtronic) curve in a Transit catheter. After 10 minutes of wiring, we were unsuccessful with a Miracle 3 wire (Abbott). The CrossBoss CTO catheter (BridgePoint Medical, Plymouth, MN) was used, and we were able to cross the CTO at first using the Miracle 3, and then the Fielder XT. Several inflations with a 1.5 x 5-mm balloon were performed, followed by successful placement of several Xience (Abbott) stents (2.5 x 8-mm, 2.5 x 12-mm, and 2.5 x 12-mm). At the end of the procedure, TIMI-3 flow was noted. The patient was brought back 30 days later for recanalization of the RCA via the right radial artery. A 5 F sheath was placed in the left groin, and a diagnostic catheter was placed for simultaneous injections. A JR4 was placed after multiple attempts to visualize the RCA. We were successful with a multipurpose catheter, showing that there was an aberrant takeoff of the RCA with a very straight proximal segment that looked like a bypass graft. Once the diagnostic study was performed, a Transit catheter was placed, followed by a Miracle 3 wire and then a Fielder XT to cross the 100% occlusion. We exchanged for the Miracle 3 wire to perform balloon angioplasty and placed several drug-eluting stents with the Xience stents. This 6-year-old occlusion was successfully recanalized. This is a case where using the radial approach allowed us to visualize the RCA, something that was not possible from the right groin. Our site is now doing radial-first procedures unless there is a contraindication. There has been increasing experience with the radial approach in the treatment of CTOs. In this case, with excellent guiding catheter support, the procedure was actually quite easy, and the CTO was easily recanalized, even though it was 6 years old. Case #3: Demonstration of the support balloon technique. A 67-year-old male underwent coronary artery bypass graft (CABG) surgery in 1983. At that time, it was documented that his RCA was 100% occluded. Because of the recurrence of angina in 1990, CABG was repeated. His coronary risk factors included hypertension, diabetes mellitus and hyperlipidemia. Two weeks prior to admission, he underwent diagnostic cardiac catheterization because of continued chest pain. His left ventricular size was normal, with a small area of apical hypokinesis at the tip of the apex and an ejection fraction of 60%. The RCA was 100% occluded, the left main coronary artery (LMCA) had minimal plaque, the LAD was totally occluded at its origin, and the left circumflex artery (LCX) was widely patent, with a previously deployed stent (also widely patent). The internal mammary graft to the distal LAD was widely patent, with a 20% stenosis at the anastomosis. The patient had been on ranolazine at 500 mg twice daily. This dose was doubled. He presented 2 weeks later with continued angina. The total RCA occlusion was felt to be the etiology for the pain he had experienced ever since his original surgery in 1983. The patient underwent bilateral access of the left and right groin arteries. A 6F diagnostic catheter was placed to allow contralateral injections of the left system to visualize the collaterals to the distal right. The LAD was occluded and there were no significant septal branches forming retrograde to the collaterals. The patient was given 6,000 units of heparin, and an AR1 (Amplatz right) 8F guide was used, along with a 3.0 x 10-mm long Sprinter balloon (Medtronic) for guiding catheter support (Figure 2). Without the over-the-wire balloon support, the guiding catheter continued to be expressed outside the RCA. With a Miracle 3 wire, minimal passage was possible into the CTO and the total occlusion was crossed with the Confianza wire (Abbott). The over-the-wire balloon was removed and the catheter was exchanged for a Transit catheter. A Gold wire was then placed into the distal portion of the RCA. The Terumo Gold wire was exchanged for a Whisper wire (Abbott) and after balloon dilatation, 2 Endeavor stents (3.0 x 12-mm and 3.0 x 30-mm) were placed. At the ostium, a 3.5 x 15-mm Endeavor stent was placed. Diminished flow was resolved by further balloon inflation and intracoronary nicardipine. The total occlusion went from 100% to a widely patent vessel with no stenosis. This is an example demonstrating the use of a support balloon technique for revascularization of a 27-year-old CTO.

Conclusion

With the introduction of newer techniques, enhanced guidewires, and operator experience, more and more CTOs are successfully treated. It is exciting to consider the future of CTO recanalization when increasingly smaller equipment is available and our ability to transverse the most difficult CTO is routinely performed. Since all centers and operators differ with their approach, it is important to share information so that continued progress can be made. At our center, we attempt to revascularize all CTOs in symptomatic patients with appropriate indications. ———————————————————————

Cardiovascular Services at St. Luke’s Medical Center Phoenix, Arizona

Cardiac Catheterization Suites Three state-of-the-art Philips digital cardiac cath suites, along with a 6-bed pre-op area. Staff 4 registered nurses, 4 radiologic technologists, 3 cardiovascular technologists, 1 unit clerk and the director. Technology

• Philips Medical Imaging • McKesson PACS • Spectranetics Laser • Bard Crosser • Abiomed Impella • Variety of CTO and atherectomy devices

CTO Volume

• Average 100–150 cases per year

St. Luke’s Medical Center is proud to announce it is now an accredited Chest Pain Center and a Cardiac Arrest Center. CTO and Device Development History at St. Luke’s Medical Center. St. Luke’s Medical Center has been treating chronic total occlusions for 28 years. Over the years, we have trained physicians in various applications for CTOs in our laboratory. We involve physicians in the community and around the country in these training courses. We have had the opportunity to work on and witness the development of CTO devices and wire technology. In 1991, St. Luke’s Medical Center was one of the few sites in the United States to first use the Magnum wire (Schneider, Zurich, Switzerland). The Magnum wire was a hollow-tip, fairly blunt device that preferentially went into the fibrous cap rather than into the subintimal space. It is no longer clinically available; however, devices such as the CrossBoss CTO catheter (BridgePoint Medical, Plymouth, MN) and the Wildcat device (Avinger, Redwood City, CA) have more recently been developed. Both use the same principle as the Magnum wire. Our group introduced the polytetrafluoroethylene (PTFE)-covered coronary stent, available today in all interventional labs for sealing off dissections. In the early 90’s, we developed the first coronary hydrophilic wire, the Jag wire, co-developed with Boston Scientific. At about the same time, we co-developed the radiofrequency wire in Japan, which became clinically available in the U.S. in the late 90’s with the Safe-Cross device (Kensey Nash Corp., Exton, PA). We are proud to have been the first site in the United States to successfully treat CTOs with the Safe-Cross. We were the first in the state to introduce the Wildcat device for peripheral CTOs and the BridgePoint device for coronary CTOs. We also introduced the Crosser system (C.R. Bard, Murray Hill, NJ). We performed and described one of the first procedures using the Crosser in the coronary arteries.1 We also were the first lab in the state of Arizona to perform the retrograde approach for chronically occluded arteries. Going through a collateral vessel, the retrograde approach allows us to advance a catheter in a retrograde fashion to the chronic total occlusion. In order to simplify and improve the retrograde approach, we also developed the Micro Elite Snare (Radius Medical, Acton, MA). ——————————————————————— The authors can be contacted via Dr. Richard R. Heuser at rheuser@phoenixheartcenter.com.

References

1. Joyal D, Afilalo J, Rinfret S. Effectiveness of recanalization of chronic total occlusions: a systematic review and meta-analysis. Am Heart J 2010;160:179–187. 2. Aziz S, Stables RH, Grayson AD, Perry RA, Ramsdale DR. Percutaneous coronary intervention for chronic total occlusions: improved survival for patients with successful revascularization compared to a failed procedure. Catheter Cardiovasc Interv 2007;70:15–20. 3. Prasad A, Rihal CS, Lennon RJ, et al. Trends in outcomes after percutaneous coronary intervention for chronic total occlusions: a 25-year experience from the Mayo Clinic. J Am Coll Cardiol 2007;49:1611–1618. 4. Hoye A, van Domburg RT, Sonnenschein K, Serruys PW. Percutaneous coronary intervention for chronic total occlusions: the Thoraxcenter experience 1992–2002. Eur Heart J 2005;26:2630–2636. 5. Olivari Z, Rubartelli P, Piscione F, et al. TOAST-GISE Investigators. Immediate results and one-year clinical outcome after percutaneous coronary interventions in chronic total occlusions: data from a multicenter, prospective, observational study (TOAST-GISE). J Am Coll Cardiol 2003;41(10):1672-1678. 6. Suero JA, Marso SP, Jones PG, et al. Procedural outcomes and long-term survival among patients undergoing percutaneous coronary intervention of a chronic total occlusion in native coronary arteries: A 20-year experience. J Am Coll Cardiol 2001;38:409–414. 7. Heuser RR, Murarka S. The Support-Balloon Technique for Chronic Total Occlusion: Successful recanalization of a 27-Year-Old. Vascular Disease Management 2010;7:E171–E174.