Successful CTO crossing relies on the operator’s ability to precisely understand the spatial relationship between the guidewire tip, the vessel architecture, and the target true lumen. Over the past decade, 3D wiring has represented a major conceptual breakthrough in antegrade CTO techniques. Tip detection is regarded as its practical and image-integrated evolution, intrinsically linked to intravascular ultrasound (IVUS) guidance.

 

The original 3D wiring concept is based on reconstructing the three-dimensional orientation of the guidewire tip by systematically analyzing its behavior under different fluoroscopic projections. By rotating the C-arm and observing the direction of wire tip movement, the CTO is mentally reconstructed as a spatial structure rather than a flat angiographic silhouette. This approach allows the operator to intentionally direct the wire toward the vessel center and along the presumed course of the occlusion. When mastered, three-dimensional wiring enables precise guidewire control and may significantly improve the success rate of antegrade CTO crossing. However, conventional 3D wiring is limited by a steep learning curve and high technical complexity, both of which restricted its widespread adoption outside selected high-volume Asian centers.

​

A potential solution to this limitation has been proposed by Japanese operators with the introduction of the tip detection method, which relies on the combined interpretation of guidewire position and IVUS imaging. Using tip detection, IVUS-guided 3D wiring becomes feasible through a manual, real-time pullback technique, allowing simultaneous visualization of the guidewire tip and the target true lumen.

​

Tip detection builds on the foundations of 3D wiring by shifting the focus from the overall wire configuration to the exact spatial relationship between the wire tip and the intended target. Rather than relying solely on wire shape and torque response, TD systematically correlates dynamic tip movement with vessel anatomy, enabling real-time recognition of whether the wire tip is oriented toward the true lumen or deviating away from it. By gently moving the IVUS transducer back and forth—typically within a range of few millimetres between the target lumen and the wire tip—the operator can reconstruct a three-dimensional mental image that directly reveals both the direction (clockwise or counterclockwise) and the magnitude of guidewire rotation. By matching fluoroscopic tip orientation with IVUS cross-sectional anatomy, the optimal wiring or re-entry direction can be precisely defined.

​

Tip Detection–Assisted Antegrade Dissection and Re-entry (TD-ADR) represents a refined evolution of classical wire- or device-based ADR techniques. In this approach, IVUS is positioned within the subintimal space or in a suitable side branch to identify the true lumen and guide controlled re-entry. A two-operator strategy is typically adopted:

• Operator 1 manipulates the stiff re-entry wire, applying TD principles to fine-tune wire orientation, torque, and advancement toward the IVUS-defined target.

• Operator 2 controls the IVUS catheter and continuously interprets real-time images, providing clock-face guidance and spatial feedback on the relationship between the wire tip and the true lumen.

 

Through constant communication between the two operators, tip detection enables subtle, incremental adjustments, minimizing uncontrolled dissection and promoting a more physiological re-entry. This approach may preserve side branches and improve long-term vessel integrity, often without the need for dedicated re-entry devices.

​​

Tip detection therefore offers a precise, reproducible, and vessel-sparing strategy for complex CTO revascularization. Importantly, TD-ADR has paved the way for a broader paradigm shift in PCI – the continuous and dynamic integration of IVUS and angiography, allowing for an unprecedented level of procedural precision in complex PCI outside of the CTO field. This concept underlies our definition of Tip Detection–guided PCI (TD-PCI).

 

On this website, you will find the fundamentals of TD-PCI, plus practical guidance on integrating it into your interventional practice according to your level of experience.