Antegrade, retrograde, and combination strategies for chronic total occlusions

Crossing Total Occlusions: Navigating Towards Recanalization

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.

A complex dissected chronic occlusion: targeted balloon dilatation of false lumen to access true lumen, combined localized subintimal tracking and re-entry, parallel wire, contralateral injection and a useful antegrade lumen re-entry technique

Chronic total occlusion (CTO) angioplasty is one of the most challenging procedures remaining for the interventional operator. Recanalizing CTOs can improve exercise capacity, symptoms, left ventricular function and possibly reduce mortality. Multiple strategies such as escalating wire, parallel wire, see-saw, contralateral injection, subintimal tracking and re-entry (STAR), retrograde wire techniques (controlled antegrade retrograde subintimal tracking, CART), reverse CART, confluent balloon, rendezvous in coronary, and other techniques have all been described. Selection of the most appropriate approach is based on assessment of vessel course, length of occluded segment, presence of bridging collaterals, presence of bifurcating side branches at the occlusion site, and other variables. Today, with significant operator expertise and the use of available techniques, the literature reports a 50–95% success rate for recanalizing CTOs.