CTO recanalization by intraocclusion injection of contrast: the microchannel technique

To assess the utilization of microinjection of contrast for the recanalization of chronic total occlusions (CTO).

Microchannels in CTOs have been considered important conduits for CTO crossing, utilizing dedicated guidewires. We postulated that microinjection of contrast immediately distal to the proximal cap of the CTO could identify and enlarge these microvessels, creating a passage for crossing the CTO with a floppy guidewire.

A total of 32 patients with a CTO were treated with this technique. Following few millimetres penetration of the proximal fibrous cap of the occlusion with a dedicated CTO guidewire, the over-the-wire balloon was advanced into the proximal portion of the occlusion, and 50-100 microg of nitroglycerine followed by 1 ml of contrast was gently injected into the occluded segment. Technical success of the microchannel technique was defined as the ability to visualize the distal true lumen with microinjection of contrast and thereafter cross the CTO with a floppy guidewire in the absence of any dissection.

Overall, technical success of the microchannel technique was obtained in 20 (63%) with angiographic success in 19. In 12 (37%) cases there was a technical failure because of dissection, and we obtained recanalization of the artery in 7 of these 12 cases with another technique. There was only one case of periprocedural myocardial infarction in an unsuccessful procedure and no major adverse cardiac events or subacute stent thromboses were observed.

Microinjection of contrast immediately distal to the proximal fibrous cap of a CTO may be an additional technique to facilitate recanalization of CTO.