Technique of CTO Recanalisation with Angioplasty

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Technique of CTO Recanalisation with Angioplasty

Complete coronary occlusions have been approached by pioneers such as Kaltenbach and Reifart in Frankfurt or Hartzler and Rutherford in Kansas City more than 30 years ago, when the materials were often inadequate and the reocclusion rate prohibitive.^33,34 The introduction of laser wires and of various devices that expected to improve success rates led to a revival in enthusiasm for CTO treatment in the early nineties. It also fostered the use of methods due to become standard, such as bilateral contrast injection for visualisation of the distal occluded vessel and assessment of the collateral circulation. However it was only in the last decade that the utilisation of percutaneous CTO recanalisation became more widespread thanks to the availability of dramatically improved wires and dedicated microcatheters, and the introduction of DES drastically reducing late failure.¹⁵ Much effort has been put forth to develop techniques to tackle these complex lesions and provide operators with strategies to optimise their success rate. The increase of success rate from 50–60 % to 80–90% of all CTOs attempted does not tell the full story because many CTO lesions routinely attempted in the last years were not even considered before, except by very few highly committed operators.³⁵ Opening complex CTOs still remains a challenge requiring a certain learning curve before the operator becomes familiar and can be highly effective, while simultaneously keeping the procedure safe. An active CTO programme with specific proctorship and guided training are indispensable elements for a centre to obtain the success rates reported above and a minimal number of 50 CTOs per year is considered essential for an operator to maintain competence.^15,36 In that direction, crucial was the rapid development of dedicated CTO PCI equipment, such as long sheaths to optimise back-up support, over-the-wire microcatheters for wire support and frequent reshaping and exchange, wires of escalating stiffness with high steerability and tapering. Balloon anchoring for active support and trapping of wires within guiding catheters to facilitate removal of long microcatheters are useful adjunctive techniques common to contemporary CTO PCI.¹⁵ Stumpless occlusions may benefit from identification of the proximal end of the occlusion with MSCT before the procedure and intravascular ultrasound during the procedure (see Figure 1). At present, CTO recanalisation strategy depends on two important parameters – coronary anatomy and operator experience both with antegrade and retrograde techniques. For operators experienced in all CTO techniques, anatomy dictates the strategy. Antegrade approach is successful in most cases and should be attempted first in the majority of the occlusions. Although a retrograde approach is needed only in a minority of lesions and collateral crossing can be very time consuming and unpredictable even in the best hands, greater than 80–90 % success rates are unattainable without the addition of 15–20 % retrograde success in lesions failed anterogradely or with no anterograde options (true ostial occlusions, unidentified stump, ambiguous track).³⁷

In case the antegrade wire cannot be advanced through the occlusion and appears to deflect to a subintimal position, a second wire can be directed towards the distal true lumen using the first as a marker (parallel wire technique) (see Figure 2). If the wire remains in the subintimal space for a longer track distal wire reentry can be attempted guided by ultrasound or using a dedicated flat balloon with lateral ports for wire exit (Sting-Ray™, Boston Scientific, USA).³⁸ Katoh established the modern era of retrograde CTO recanalisation, guiding the development of dedicated microcatheters (Corsair®, Asahi Intecc, Japan) and delicate highly steerable wires (Sion, Fielder XT-R, Asahi Intecc, Japan) for use of tortuous septal and epicardial collaterals to probe the occlusion retrogradely, joining anterograde and retrograde wires with balloon inflation in the occlusion⁹. The externalisation of a long 330 cm 0.010 inch (0.26 mm) diameter RG3 wire (Asahi Intecc, Japan) after retrograde crossing post reverse controlled antegrade retrograde subintimal tracking (CART) became the final step in most of these complex procedures, providing excellent back-up support and allowing anterograde completion of the procedure (see Figure 3). Second generation DES have been shown to reduce restenosis and reocclusion, while experienced operators have high thresholds for treating proximal or distal disease outside the occluded segment, often due to become less prominent and not flow limiting with the growth of the vessel after flow restoration. Recently Brilakis et al. codified a strategy of initial selection and rapid switching from antegrade to retrograde approach should the initial strategy fail based on lesion characteristics and response, developing an unconventional use of rapid wire progression in the subintimal space knuckling it against the occlusion.³⁹ The incidence of complications remains low when these procedures are performed by experienced operators and high volume laboratories, despite the long procedural duration and use of multiple aggressive wires and catheters.⁴⁰ Wire exits are the norm in these procedures and are uneventful if promptly recognised and addressed. Drainage of pericardial tamponade and sealing of perforations with covered stents or microcoils are very rarely required but can be life-saving and the operator should be familiar with their use.