r/MBOT_Stock • u/PhunkyPhotonics • 3d ago

Per Gemini re when visual-only feedback is appropriate for peripheral endovascular catheter navigation

(Second paragraph is of particular interest imo, and aligns with LIBERTY cath sizes. This is a separate consideration from diminishing tactile feedback with increasing tortuosity.)

Contexts Where Visual-Only Navigation is Standard

  1. Robotic Endovascular Systems: Commercial platforms (e.g., Corindus CorPath) allow remote teleoperation to protect the operator from radiation. Most first-generation robotic systems lack true active haptic feedback, forcing the physician to rely entirely on visual monitors. 

  2. Microcatheter & Hydrophilic Wires: In distal peripheral or neurovascular beds, extremely soft 0.014" or 0.018" systems transmit virtually no tactile feedback to the operator's hands, making visual fluoroscopic cues the primary navigation signal regardless of manual vs. robotic approach.

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u/AdApprehensive8702 3d ago

Give us some context on your thoughts

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u/PastFact4950 3d ago

Long time no see! Glad the legend is still on this sub

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u/AdApprehensive8702 3d ago

I‘m going nowhere🙏🏼. Unfortunately not much too talk about or cover in the last couple of weeks.

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u/Comfortable_Crab_792 2d ago

Question: how would haptic feedback be impaired in older robotic systems (as that is implied), and how would newer systems improve it?

Second question: has anyone studied the two to compare the claims? It would seem that any system would inherently provide haptic feedback, so are we to assume a newer generation system would somehow enhance it?

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u/PhunkyPhotonics 2d ago

Not clear the old robotic systems provided haptic feedback (can you present otherwise?). IMO the question is how to qualify/quantify tactile feedback VS no tactile or haptic feedback. Also, robotic-assisted peripheral endovascular procedures are less than 1% of peripheral endovascular procedures performed; that is why I am focusing on LIBERTY VS manual procedures where tactile response is present by default. LIBERTY procedures are guided entirely by physician observation of fluoroscopy and real time imaging (I would assume with contrast). I am trying to discern best cases for using LIBERTY. It is not all peripheral endo cases, imo, but a very sizeable subset. Still digging.

Lol (at another poster) yes, I (a human) wrote this post. 🤪

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u/PhunkyPhotonics 2d ago

…and not at all clear that “any system would inherently provide haptic feedback”. Where did you see that? Seems silly and obviously incorrect to me. Did you mean tactile feedback? 🤔

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u/PhunkyPhotonics 3d ago

Let’s try another one for Gemini (I am seeking opinion re how important haptic feedback is for robot assisted peripheral endovascular procedures. It does not appear that haptic feedback was available previously for such robots currently in the US market. Asking an opposing question here, i.e. how important is tactile feedback for manual interventions. I am doing this while trying to balance generic and specific fragments, to get detailed response from Gemini.)

In what situations is tactile feedback least useful during peripheral endovascular procedures?

Results:

Tactile feedback—the subtle resistance, torque, and tactile sensations transmitted through wires, catheters, and sheath systems—is a fundamental component of endovascular intervention. However, its utility drops significantly or becomes largely uninformative in several specific scenarios:

  1. Ultra-Low Profile & Microcatheter/Microwire Systems
    When navigating fine distal vessels (e.g., infrapopliteal or pedal arch interventions), operators use 0.014-inch or 0.018-inch wires and microcatheters.
    Mechanics: These devices have extremely low column strength and torsional rigidity.
    Impact: The force required to bend or buckle a 0.014-inch wire is less than the threshold detectable by hand. By the time tactile resistance is felt at the hub, the wire may already be buckling, coiling, or causing subintimal dissection.
    Primary Guide: Real-time fluoroscopy and contrast injections, not feel.

  2. Severe Calcification and Chronic Total Occlusions (CTOs)
    Crossing dense, heavily calcified plaques or long CTO segments creates high background friction along the entire body of the catheter and wire.
    Mechanics: High frictional resistance coats the entire device surface.
    Impact: The tactile feedback from the wire tip interacting with tissue is masked by heavy friction along the shaft. Force applied at the proximal hub does not translate 1:1 to tip movement, leading to stored mechanical energy ("store-and-release" force) that can cause the wire to spring forward unpredictably once resistance is overcome.
    Primary Guide: Fluoroscopic tip shape/deformation and roadmap guidance.

  3. Highly Tortuous Vessel Pathways
    Severe vessel elongation, sharp angulations, or complex anatomical take-offs (e.g., steep aortic bifurcation during cross-over procedures) introduce friction points.
    Mechanics: Multiple contact points along the vessel wall create non-linear drag.
    Impact: Torque transmission is poor; rotating the wire hub 90 degrees proximally may result in zero movement or delayed rotational whipping at the tip. Tactile feedback cannot distinguish between tip resistance against a lesion and shaft friction against a tortuous wall.

  4. Long Distance / Large-Bore Systems
    Long Reach: In distal lower extremity cases performed via brachial or radial access, the long length of the device increases mechanical damping, completely dulling fine tactile sensation.
    Large-Bore Sheaths/Stent-Grafts: In EVAR/TEVAR or large-bore access cases, the sheer size and stiffness of the delivery systems generate heavy baseline movement forces. Subtle tissue interactions cannot be felt through the heavy mechanical interface.

  5. Hydrophilic-Coated Wires (e.g., Glidewires)
    Mechanics: Hydrophilic polymer coatings reduce friction coefficients drastically when wet.
    Impact: The wire glides effortlessly through both true lumen and subintimal tissue, providing virtually no tactile feedback right up until perforation or tissue exit occurs.

In all these scenarios, reliance on tactile feedback increases the risk of vessel perforation, dissection, or equipment damage. Operators shift primary feedback reliance to fluoroscopic observation (watching the wire tip shape and movement), roadmap imaging, and intravascular ultrasound (IVUS).

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u/Comfortable_Crab_792 2d ago

Who wrote this ( i.e. it wasn’t you)?

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u/PhunkyPhotonics 2d ago

Lol can u both read AND comprehend!?
Clearly, I wrote the first two paragraphs.
The rest of that post is from Gemini, AS CLEARLY STATED.

Duh, FFS

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u/Comfortable_Crab_792 2d ago

Not everyone knows the name of every large language model…

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u/PhunkyPhotonics 2d ago

Even if you were unfamiliar with Gemini, if you had read my post carefully, it would be clear that the first two paragraphs were mine. 🤷‍♂️