The Smart Catheter Project: Using Ultrasound at the Tip to Boost First-Pass Thrombectomy

Speakers: Dr Naga (neuroradiology) & Dr Nishal (ultrasonics)
Topic: Catheter-tip ultrasound sensing to guide clot-removal strategy in large-vessel occlusion stroke

Mechanical thrombectomy has transformed outcomes for selected stroke patients but interventionalists still face a stubborn constraint: first-pass effect (complete reperfusion on the first attempt) sits at ~30–40% across studies. Each extra pass risks emboli, delays reperfusion, and adds cost. The presenters laid out a compelling engineering path: use ultrasound at the catheter tip to “see” clot morphology in real time and pick the right tool and technique before the first pull.

The clinical engineering problem behind the numbers

• We can find the clot, not its nature. Imaging localises an occlusion, but can’t definitively label its composition (soft/red vs organised/fibrin-rich/calcific) or adhesion at the moment of engagement.
• Technique/device choice varies. Operators pick aspiration, stent retriever, or combination based on experience—without definitive intraluminal feedback.
• Time is brain. Every minute of delay costs outcome; more passes mean more minutes.

“What if the catheter could tell you—before the first pass—what you’re dealing with?”

The concept: miniaturised ultrasound sensing at the tip

Dr Nishal outlined a design aimed at giving tactile-like feedback from within 2–3 mm vessels:

• Miniaturisation: Target ≤0.2 mm elements without compromising catheter flexibility.
• Frequency vs penetration: Small elements push frequencies up (~200–300 MHz), increasing resolution yet reducing penetration—demanding careful trade-offs.
• Impedance matching: Blood/tissue have low acoustic impedance; classic ceramic transducers reflect energy. Thin-film/structured materials and matching layers widen bandwidth and push energy into the medium.
• Manufacturing: Exploring thin-film piezoelectric deposition and advanced micro-fabrication (including scaffold-grown piezo structures) for sensitivity at very small apertures.
• Durability: Must withstand aspiration forces—no delamination, no debris risk.

How it could change first pass

If the tip can classify clot stiffness/morphology and adhesion, it can:

• Inform device and technique selection (aspiration vs retriever vs combined; dwell times; pull speeds).
• Reduce passes, procedure time and embolisation risk.
• Improve door-to-reperfusion KPIs—central to NHS stroke ambitions.

A vivid case shared in the session—rapid language and motor recovery immediately after reperfusion—underlines the stakes: getting it right on the first attempt matters.

Where the project is now

• Stage: Early research. 6–12 months to benchtop prototypes (synthetic clots in model vessels), 3–5 years to a clinical-grade device subject to regulatory pathways.
• Collaborators: Birmingham City University, clinical partners, and materials/fabrication groups (including Singapore).
• Forward look: From 2D to 3D localisation, and pushing <1 m system-level accuracy in adjacent locationing research (relevant for lab navigation and hybrid approaches).

What clinical engineers can do today

• Engage R&I early: If your Trust runs thrombectomy, connect the stroke service with your R&D governance to scope pre-clinical evaluation channels.
• Contribute to testbeds: Share experience on catheter robustness, aspiration dynamics, and sterile pathway constraints; help define verification & validation protocols.
• Map integration: Consider how tip-sensing would feed imaging, recording, and PACS/registry data for audit and learning.

NHS alignment

Improving first-pass reperfusion and compressing door-to-reperfusion times directly supports the Long Term Plan’s aims to expand thrombectomy and improve stroke outcomes—better function, shorter stays, lower long-term costs.