Recanalization of an Occluded Right Coronary Artery into the Right Internal Mammary Artery Using a Retrograde Approach

Chronic total occlusions (CTO) remain one of the most technically challenging areas of coronary intervention. As a result, new innovative techniques are continually being developed in an effort to improve the procedural success rate of CTO recanalization.¹ A retrograde approach to cross CTOs has recently been described,² which may increase the options available when the anterograde approach has failed, provided there are retrograde collaterals to the distal vessel. Here, we describe a modification of this technique in which we retrogradely crossed an occlusion of a distal right coronary artery (RCA) into a proximally anastomosed bypass graft, rather than the proximal native vessel.

Case Report. A 51-year-old male with worsening angina was admitted for percutaneous coronary intervention (PCI) after a dobutamine stress echocardiogram demonstrated infero-posterior and lateral ischemia. He had an extensive history of coronary revascularization in other institutions, starting with coronary artery bypass surgery in 1994, in which he received a left internal mammary artery (LIMA) graft to the mid-left anterior descending artery (LAD), a right internal mammary artery (RIMA) graft to the mid-RCA, and a saphenous vein graft to an obtuse marginal branch (OM). In the 9 months prior to the current procedure, he underwent the following: (1) stenting of the RCA distal to the RIMA insertion in September 2005; (2) stenting of the circumflex artery (Cx) into an OM in November 2005; and (3) stenting of the mid-Cx in February 2006. During his last intervention, it was noted that he had a total occlusion of the RCA in the previously-stented segment. On this occasion, coronary angiography confirmed proximal occlusion of the native RCA. The RIMA to the mid-RCA was patent but tortuous, and there was occlusive in-stent restenosis (ISR) immediately distal to its anastomosis (Figure 1A). The distal RCA filled both anterogradely via small bridging collaterals and retrogradely via septal collaterals from the LAD. The LAD also had severe tandem stenoses in its proximal and mid-portion (Figure 1B). The stents in the Cx and OM were patent. The LIMA was small and atretic.
Our planned strategy was to attempt to cross the occlusive in-stent restenosis in the mid-RCA via the RIMA, as the proximal RCA occlusion was longstanding and anatomically unfavorable for reopening. Unfortunately, despite adequate guide catheter support and utilizing an over-the-wire (OTW) technique, we failed to effectively cross the occlusion and created a subintimal path with the following succession of different guidewires: Universal (Guidant Corp., Indianapolis, Indiana), Pilot 200 (Guidant), Conquest and Conquest Pro (Asahi Intecc, Tokyo, Japan). At this point, we opted to switch to a retrograde approach utilizing the septal collaterals from the LAD to the posterior descending (PDA) and postero-lateral arteries (PLA). Using a 6 Fr guide catheter which was shortened according to a previously-described technique,³ a 1.5 x 20 mm OTW balloon and a Whisper MS hydrophilic-coated guidewire (Guidant) were advanced into the PDA via a septal branch of the LAD without the need for dilatation of the septal branch (Figure 2). The hydrophilic wire was then exchanged for a floppy wire (Balance Middle Weight 300 cm, Guidant) which crossed the CTO retrogradely into the mid-RCA and then into the RIMA. The 1.5 x 20 mm OTW balloon was then used to dilate the lesion retrogradely. This restored anterograde flow and allowed the lesion to be crossed anterogradely with a Whisper MS wire (Guidant) from the RIMA. Without further predilatation, the mid-to-distal RCA was stented with 3 overlapping 3.0 x 33 mm CoStar stents (Conor MedSystems, Menlo Park, California) deployed from the anterograde direction. The final angiographic result was excellent with TIMI 3 anterograde flow in the distal RCA (Figure 3).

Discussion. To our knowledge, this is the first published report of retrograde recanalization of a CTO into a bypass graft and thus highlights that this procedure can be performed even in the most challenging coronary anatomy. The basic principle of the retrograde approach is to cross a CTO with a guidewire, distally to proximally, utilizing a “visible” retrograde collateral originating from another native coronary artery. Generally, the aim is to open up either a true or false lumen within the occluded segment that will then allow an anterograde wire to enter the true distal lumen for subsequent stent deployment. If it proves impossible to advance a balloon into the occlusion retrogradely, then the wire may at least act as an accurate marker of the true distal lumen’s position for a conventional anterograde approach. There are a number of implications inherent in the technique. Dual intubation of both the occluded artery and the coronary artery from which the retrograde collaterals originate is mandatory. A 90 cm guide catheter is usually necessary (if a long balloon catheter is not available) to negotiate the wire across the collateral and retrogradely to the site of the occlusion. The operator may also need to perform gentle dilatation (1 or 2 atmospheres) of the collateral vessel to allow equipment to advance to the occlusion site.
The challenges of this procedure include passing the guidewire across the retrograde collateral into the distal vessel and having done so, advancing equipment to the occlusion in the target vessel. In our experience, the angiographic size of the septal collateral is not predictive of success, and often a number of different septal branches have to be attempted before crossing into the distal vessel is successful. An advantage of wiring septal collaterals for the retrograde approach is their resistance to spasm, which frequently occurs when wiring epicardial collaterals. Our approach involves using a floppy hydrophilic wire (such as a Whisper) to cross the septal. However, to puncture the distal cap, the hydrophilic wire often has to be exchanged for a more specialized guidewire. In some difficult lesions, the only way to progress is to create a subintimal retrograde dissection and gain access to the lumen at the proximal end of the occlusion.⁴ Contrary to all these concerns, in this particular case, a floppy wire supported by the balloon catheter was able to retrogradely cross the occlusion.
In conclusion, this retrograde technique increases the therapeutic options available for recanalization of a CTO when the anterograde approach has failed.

References

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2. Rosenmann D, Meerkin D, Almagor Y. Retrograde dilatation of chronic total occlusions via collateral vessel in three patients. Catheter Cardiovasc Interv 2006;67:250–253.
3. Stratienko AA, Ginsberg R, Schatz RA, Teirstein PS. Technique for shortening angioplasty guide catheter length when therapeutic catheter fails to reach target stenosis. Cathet Cardiovasc Diagn 1993;30:331–333.
4. Surmely JF, Tsuchikane E, Katoh O, et al. New concept for CTO recanalization using controlled antegrade and retrograde subintimal tracking: the CART technique. J Invasive Cardiol 2006;18:334–338.