title: Crossing Total Occlusions: Navigating Towards Recanalization.
abstract: Chronic total occlusions (CTOs) represent the "last frontier" of percutaneous interventions. The main technical challenges lies in crossing the guidewire into the distal true lumen, which is primarily due to three problems: device buckling during initial puncture, inadequate visualization, and the inability to actively navigate through the CTO. To improve the success rate and to identify future research pathways, this study systematically reviews the state-of-the-art of all existing and invented devices for crossing occlusions. The literature search was executed in the databases of Scopus and Espacenet using medical and instrument-related keyword combinations. The search yielded over 840 patents and 69 articles. After scanning for relevancy, 45 patents and 16 articles were included. The identified crossing devices were subdivided based on the determinant for the crossing path through the occlusion, which is either the device (straight and angled crossing), the environment (least resistance, tissue selective, centerline, and subintimal crossing) or the user (directly steered and sensor enhanced crossing). It was found that each crossing path is characterized by specific advantages and disadvantages. For a future crossing device, a combination of crossing paths is suggested were the interventionist is able to exert high forces on the CTO (as seen in the device approach) and actively steer through the CTO (user: directly steered crossing) aided by intravascular imaging (user: sensor enhanced crossing) or an intrinsically safe device following the centerline or path of least resistance (environment: centerline crossing or least resistance crossing) to reach the distal true lumen.
authors.affiliation: Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands. a.sakes@tudelft.nl.
authors.forename: Aimée
authors.initials: A
authors.lastname: Sakes
authors.affiliation: Department of Biomedical Engineering, Erasmus Medical Center, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Regar
authors.affiliation: Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands.
authors.forename: Jenny
authors.initials: J
authors.lastname: Dankelman
authors.affiliation: Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Breedveld
mesh_terms: D054059:Coronary Occlusion / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D062645:Percutaneous Coronary Intervention
keywords: Chronic total occlusions (CTO); Crossing; Percutaneous coronary intervention (PCI); Recanalization; Review; State of the art; Treatment
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