Microcatheter knuckle technique: A novel technique for negotiating the subintimal space during chronic total...

To establish if novel microcatheter knuckle technique (MKT) is feasible and efficacious in negotiating the subintimal space in difficult lesions during chronic total occlusion (CTO) percutaneous coronary intervention (PCI).

CTOs remain one of the most challenging lesion subsets in PCI. Guidewire manipulation and advancement of equipment within the subintimal space is sometimes challenging and aggressive manipulation in the subintimal space is feared, because of concern of vessel disruption and perforation. Here we introduce the MKT, for negotiating the subintimal space during challenging CTO PCI.

MKT is performed by creating a wire knuckle with polymer-jacketed guidewire and positioned in the subintimal space. Subsequently, a tapered-tip, kink-resistant microcatheter is advanced towards the knuckled tip of guidewire and the guidewire is simultaneously withdrawn; creating a knuckle-shaped microcatheter tip. The MKT was considered in CTO PCIs that involved subintimal techniques where resistance to guidewire knuckle advancement was encountered. Procedures were performed between March 2013 and June 2017 at our institution.

During the study period, a total of 440 CTO PCIs were performed, from which seven were treated with MKT. MKT was successful in six patients and technical success was achieved in all seven patients. The MKT was successfully performed with both the antegrade and retrograde approach.

We present a novel technique for negotiating the subintimal space in CTO PCI for cases where significant resistance is experienced restricting guidewire or material advancement in antegrade or retrograde dissection. The MKT appears to be efficacious complementing the CTO operator's armamentarium.