Q&A: Rethinking Covered Stent Deliverability

Q: Why do covered stents still struggle with deliverability compared to bare‑metal stents?

Because coverage traditionally comes at a mechanical cost.

Bare‑metal stents are essentially flexible scaffolds. Once a polymer membrane is added, wall thickness increases, stiffness rises, and the stent begins to behave less like a conformable structure and more like a rigid tube. In tortuous or calcified anatomy, that difference is immediately felt by the physician during delivery.

This is the classic endovascular engineering tug‑of‑war: structural integrity versus navigation.

Q: What is the “Profile–Deliverability Paradox” physicians talk about?

It’s the persistent tradeoff between therapy and access.

Clinicians value covered stents for sealing perforations, excluding aneurysms, and preventing tissue ingrowth,but they often avoid them in challenging anatomy. Traditional designs tend to straighten vessels rather than conform to them, introducing biasing forces that can increase vessel trauma and edge complications.

In practice, physicians are forced to choose between:

• What the lesion needs, and

• What the anatomy will allow them to deliver

At Medibrane, we don’t see this as an unavoidable compromise,we see it as a materials problem.

Q: Why does bulk matter so much in endovascular delivery?

Because every micron adds friction, stiffness, and access limitations.

Conventional graft materials such as ePTFE or PET can significantly increase the crimped profile of a stent. That often forces larger French sizes, limiting patient eligibility and making navigation through tight curves more difficult.

Deliverability doesn’t fail catastrophically,it degrades incrementally. And bulk is usually the first culprit.

Q: How does Medibrane reduce stent bulk without sacrificing coverage?

By rethinking how membranes are made.

Medibrane uses Microlayer Polymer Deposition to create ultra‑thin, highly uniform membranes with wall thicknesses starting around 15 microns,a fraction of traditional graft materials.

For perspective, a human hair is roughly 70 microns thick.

What this enables:

• Dramatically lower crimped profiles

• Compatibility with delivery systems typically reserved for bare‑metal stents

• Full coverage performance without “bulky device” behavior

Q: Why are sutures and double‑layer designs a problem?

Because they add stiffness exactly where flexibility is needed.

Historically, membranes have been secured to Nitinol frames using sutures or full encapsulation (“sandwich” designs). Both approaches introduce mechanical penalties:

• Sutures create localized stress points and friction during delivery

• Double layers significantly increase axial and bending stiffness

The result is a covered stent that fights anatomy instead of following it.

Q: What is sutureless lamination and why does it matter?

Sutureless lamination bonds the membrane directly to the stent frame without stitching or encapsulation.

Medibrane can laminate the membrane selectively to the inner diameter (ID) or outer diameter (OD) of the stent, eliminating redundant material and preserving the native mechanical behavior of the Nitinol.

The outcome:A covered stent that retains shape memory, flexibility, and trackability—without the drag and rigidity of legacy attachment methods.

Q: Doesn’t coating the stent still make it stiff?

It can,if done continuously.

A fully coated stent behaves less like a spring and more like a tube. When every strut is locked together by polymer, independent movement is lost, and conformability suffers.

That’s why Medibrane uses Selective Bonding.

Q: What is selective bonding, exactly?

Instead of continuous coverage, the membrane is bonded only at strategically defined contact points—think of a “dot‑matrix” rather than a solid shell.

This allows:

• Individual struts to move independently

• The stent to flex naturally through curves

• Reduced vessel straightening and edge stress

The polymer provides coverage without dictating the mechanics.

Q: How does this impact clinical outcomes?

Mechanics matter clinically.

A stent that conforms to anatomy:

• Reduces trauma at stent edges

• Preserves natural vessel geometry and hemodynamics

• Lowers the risk associated with biasing forces and over‑constraint

Deliverability isn’t just about convenience—it’s about safety and durability.

Q: What is Medibrane ultimately trying to achieve?

A covered stent that doesn’t feel covered.

The goal is a device that:

• Tracks like a micro‑catheter

• Conforms like bare metal

• Performs like a state‑of‑the‑art stent graft

By minimizing profile, eliminating redundant layers, and preserving mechanical freedom, we are closing the gap between what physicians need and what current devices allow.

Q: Is the “deliverability gap” inevitable?

No.

It’s not a law of physics,it’s a design constraint driven by materials and manufacturing choices. And those choices can be re‑engineered.

Is your current covered stent design hitting a flexibility or profile ceiling?Medibrane partners with innovators to enable thinner, more conformable endovascular solutions—without forcing a platform redesign.

Let’s make covered stents feel naked again.