Retrograde Approach to Chronic Total Occlusions: Can Septal Vessels Be Used More Than Once?

From the Cardiovascular Intervention Department, University Hospitals of Leicester, United Kingdom. The authors report no conflicts of interest regarding the content herein. Manuscript submitted May 29, 2009, provisional acceptance given August 11, 2009, final version accepted September 8, 2009. Address for correspondents: Albert E. Alahmar, MD, Cardiovascular Intervention Department, Leicester University Hospitals of Leicester Glenfield Hospital, Leicester, United Kingdom LE3 9QP. E-mail: ae.alahmar@gmail.com

_______________________________________________ ABSTRACT: Chronic total occlusions constitute about one-third of all coronary artery lesions, and remains a significant challenge for the interventionist. Over the last few years, several new developments have emerged. The retrograde approach is one of those new developments and certainly, in experienced hands, has improved success rates significantly. This approach, however, often requires more than one attempt and potentially uses the same septal branch between the donor and the occluded artery. We present 2 cases where a second attempt at the retrograde approach was unsuccessful because of changes in the septal collateral, which having previously allowed passage of the balloon, failed to do so on the subsequent attempt.

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J INVASIVE CARDIOL 2009;21:E234–E236 Key words: CTO, septal collateral Chronic total occlusions (CTO) constitute a large proportion (25–30%) of all significant coronary stenoses1 and remains one of the last frontiers of coronary intervention. Japanese CTO experts have led the field with new techniques, particularly with the development of the retrograde approach as a standard treatment for certain patients who have unfavorable anatomy for a routine anterograde approach or in whom the anterograde approach has failed. This approach has raised success rates to 87%.2 Thus, there is a push to master the retrograde approach, particularly among practitioners with an interest in this interventional area. For the retrograde approach to be successful, there are a number of prerequisites.3 First and foremost, there has to be a usable collateral channel from the donor artery to the distal occluded vessel and careful preparation of any such case entails viewing non-panned angiographic images in specified views to attempt to identify appropriate, potentially usable retrograde collateral vessels (Figure 1). We present two cases where a second attempt at the retrograde approach was unsuccessful because of changes in the septal collateral, which having previously allowed passage of the balloon, subsequently failed to do so. Case 1. A 57-year-old female presented in 2008 with recurrent angina 8 years post coronary artery bypass grafting (CABG). Her CABG involved left internal mammary (LIMA) grafting to the left anterior descending (LAD) artery plus 4 grafts placed to other stenosed vessels. At coronary angiography in 2008, all except the vein graft to the right coronary artery (RCA) were patent. The native RCA was occluded and was fed by septal collaterals from the LAD supplied by the LIMA graft. An attempt was made to open the long RCA occlusion via an anterograde approach, but as this was unsuccessful, she was therefore referred for a retrograde approach via an identifiable retrograde septal collateral. A Fielder guidewire (Asahi Intecc, Japan) was used to gain access to the distal RCA and the septal vessel was dilated with a 1.25 mm x 10 mm balloon (Figure 2). Despite multiple attempts through different wire exchanges, the distal cap of the occlusion could not be penetrated, and at appropriate dye and radiation time limits, the attempt was abandoned. She was brought back to a live CTO course for a repeat retrograde procedure to be undertaken by a Japanese expert on the presumption that collateral access would not be the problem and that expert navigation of the distal cap was what was required (Figure 3). The retrograde septal collateral that had been present previously and used to access the distal RCA was no longer present. Despite numerous attempts to identify and use other collaterals, the retrograde approach had to be abandoned. A further anterograde approach was then tried and was successful using specialty wires and balloons (routine Fielder wire from Abbott Vascular, Abbott Park, Illinois; and the RunthroughTM balloon from Terumo Medical, Japan) (Figure 4). Case 2. A 67-year-old male had also undergone previous left internal mammary artery (LIMA) grafting and re-presented with recurrent angina identified on non-invasive imaging as coming from an occluded RCA. The anterograde approach was not attempted due to the very proximal nature of the occlusion. A retrograde approach was attempted via a good retrograde septal collateral which was supplied via the LIMA to LAD graft. The Fielder wire was delivered to the distal RCA and the septal vessel was dilated with a 1 x 10 mm Falcon 160 cm length over the wire (OTW) balloon (Invatec SpA, Roncadelle, Italy ) and the same balloon was delivered to the distal RCA (Figure 5). The CART procedure (retrograde subintimal tracking of wire and balloon create a space large enough for the antegrade wire to penetrate and to then access the distal true lumen) was then attempted, but was unsuccessful. The operator felt a second attempt likely to be more successful after discussion with other experts regarding the CART technique.4 The patient was thus brought back for a second retrograde attempt. The same retrograde collateral was wired with the same previous wire, but no balloon (even a 0.85 x 10 mm) balloon would track beyond the point of the previous septal dilatation (Figure 6). The second attempt had to be abandoned because of dye and radiation limitations. Discussion. These two cases demonstrate a retrograde approach to treat CTO where failure/abandonment of a first retrograde attempt after delivery of the wire to the distal artery and dilatation of the septal collateral resulted in changes in the septal collateral, making it subsequently unusable as a retrograde conduit at further retrograde attempt. Since the retrograde approach to treat percutaneously complex and challenging CTO was introduced by Japanese experts,3 the success rate has been close to 90%.2 With that success rate, this approach may become the future treatment for this common and very challenging form of coronary disease. However, this approach may require more than one attempt to achieve its goal.3 One of the key factors for the first and second attempts is the integrity of the septal collateral between the donor and the occluded receiver artery. Furthermore, the same septal vessel used in the first attempt might be the only collateral that can be used in the second one. Hence, it is important to know how these septal collaterals behave after wires and balloons have been used in them. The two cases here showed that it is unlikely that these septal collaterals would be able to maintain their integrity after the first attempt. Although we are not certain as to how common this may be, the message appears clear. While it is true that certain retrograde septals that appear to connect to the distal occluded vessel may indeed not allow passage of the wire and balloon, and certain apparently non-connecting collaterals may indeed do so because of failure to identify the microchannels due to image resolution, in general, the presence of a good identifiable retrograde collateral vessel will improve the chances of success.2 There exists the possibility that if a retrograde CTO fails following septal dilatation, this septal vessel may not be usable in future attempts. As more interventionists are learning the retrograde approach, it may be that this should be kept in mind and that these procedures should be done in the presence of an operator with greater experience and who is thus more likely to turn a procedure that fails despite getting a wire and/or balloon to the distal occlusion into a successful one. Coming back to re-try via the same septal vessel may not guarantee it is still available.

2. Rathore S, Matsuo H, Suzuki T, at al. Procedural and in-hospital outcomes after percutaneous coronary intervention for chronic total occlusions of coronary arteries 2002 to 2008: Impact of novel guidwire techniques. JACC Cardiovascular Interv 2008;2:489–497.

3. Wu EB, Chan WW, Yu CM. Retrograde chronic total occlusion intervention: Tips and tricks. Catheter Cardiovascular Interv 2008;72:806–814.

4. Carlo M, Godino C, Colombo A, at al. Subintimal tracking and re-entry technique with contrast guidance: A safer approach. Catheter Cardiovasc Interv 2008;72:790–796.