Slides
| Retrograde CTO intervention |
| Retrograde approach through the collateral channels has been recently proposed and has the potential to improve the success rate of percutaneous coronary intervention (PCI) in chronic total occlusion (CTO) lesions of the coronary arteries. Several reasons can be proposed for increased success rate of retrograde approach. Firstly, previous failed attempts of antegrade approach induce intimal dissection, and as a result the anatomy becomes more difficult on future occasions for further antegrade attempts. Secondly, the distal cap of the CTO lesions is hypothesized to be softer than the proximal cap. Thirdly, the entry point into the CTO lesions, which is inferred from the angiographic appearance, is sometimes wrong. The length and duration of the CTO determines the difficult of crossing. The presence of calcium on fluoroscopy usually means a long and difficult procedure. CT coronary angiography can further determine the difficulty of the CTO as well as elucidate the course of the coronary artery. The introduction of improved guidewires and novel devices has increased the success rate of CTO PCI. Like all PCI, case selection is the most important task and one that is difficult to get right. A thoughtful balance between the difficulty and risk of the procedure, the size of the ischemic territory, the symptoms of the patient, and the skill and experience of the operator should be sought and used as a guide toward therapy. Although the difficulty and risk of the procedure is based upon the combined difficulty of finding a good guiding catheter, crossing the collateral channel, crossing the CTO, and subsequent difficulty with stenting. The tortuousity of the collateral channel is the major contributor to difficult and risk of collateral channel crossing. Tortuous collateral channels are more difficult to negotiate and more prone to rupture upon dilatation. Septal collateral channels tend to be less tortuous than circumflex to right coronary or epicardial collaterals. The visibility of the collateral channel is also important. Although we can often negotiate through invisible septal collateral channels, it is much easier to negotiate through visible channels when the operator can use antegrade injection to guide the wire movement. It is important to take multiple orthogonal views of the collateral channels before deciding upon starting a retrograde procedure as some very straight looking collaterals can in fact be Z shaped in another view. Septal channel access is reasonably safe. However, rupture of epicardial collateral channels can lead to tamponade. Also, epicardial collateral tortuousity can lead to accordion effect and occlusion of collateral flow and subsequent ischemia. Septal collateral channel crossing from the LAD to RCA is generally easier than from RCA to LAD. This is because the LAD septal origin is usually free from tortuousity, whereas the RCA septal collaterals often arise with considerable tortuousity. Also it is often easier to be certain that the retrograde wire is in the right coronary than it is in the LAD as the wire travels along the C shaped curve of the RCA after crossing the collaterals. Therefore the criteria for easy collateral channel crossing are nontortuous, visible, septal collateral channels, preferably from LAD to RCA and without other collateral supply to the occluded artery. Patients with these characteristics could be considered candidates for retrograde approach. Six strategies in a retrograde approach have been proposed according to the CTO lesion characteristics and clinical situation including just landmark, kissing guidewire, CART technique, retrograde proximal true lumen puncture, catching the retrograde guidewire, retrograde true lumen tracking. Thus, a retrograde approach requires a combination of techniques, which have to be chosen on an individual basis according to the patient condition. |
| REFERENCES |
| 1. Wu EB, Chan WW, Yu CM. Retrograde chronic total occlusion intervention: tips and tricks. Catheter Cardiovasc Interv. 2008;15;72:806-14. 2. Saito S. Different strategies of retrograde approach in coronary angioplasty for chronic total occlusion. Catheter Cardiovasc Interv. 2008;71:8-19. |
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