A New Modular Approach to Venous Stenting With ALTA's Multi-Segmented, Tapered Design

The world’s first in-length adjustable multisegmented tapered variable venous stent will be showcased at LINC this afternoon, exploring its potential in overcoming some of the limitations of contemporary venous stenting. 

LINC Today caught up with the stent founder Cees Wittens, Emeritus Professor of Venous Surgery at Maastricht University Medical Center (UMC+, the Netherlands) and the European College of Phlebology (ECoP) to find out more about the device in question – the Venous Stent ALTA® – and what characteristics and experience he will be sharing with the LINC audience. 

What unmet needs in deep venous stenting motivated the development of ALTA?

The development of the ALTA in-length adjustable, multi-segmented venous stent was driven by fundamental biomechanical and biological shortcomings of today’s purpose-built venous stents. 

Current venous stents are manufactured as long, continuous tubular structures that attempt to impose a fixed, factory defined geometry onto a living, compliant and constantly moving vein. In practice, veins are not straight tubes. They curve, taper, dilate and change shape with posture, respiration and flow. Forcing a rigid geometry into this environment leads to several predictable failure mechanisms. 

First, conventional nitinol stents progressively straighten after implantation as they attempt to return to their original manufactured shape. This straightening can create kinks, protrusions and areas of ‘curtaining’ at connection points or bends, where stent material protrudes into the lumen and impairs inflow or outflow. This is a direct cause of restenosis and chronic pain in a subset of patients, sometimes severe enough to require stent removal. 

Second, most current venous stents have low porosity designs. This has several consequences. Inflow from side branches is restricted, reducing total venous inflow into the stented segment and thereby lowering flow velocity and patency. Outflow from collateral veins into the stented conduit is also impaired, reducing the effective drainage capacity of the limb. At the cellular level, low porosity means that a large proportion of endothelial cells are crushed beneath the struts, with up to 60 to 70% cell loss behind the metal framework. This delays endothelialization of the struts, prolongs thrombogenic exposure of nitinol and drives the need for extended anticoagulation. 

Third, because iliofemoral disease almost always spans at long and variable lengths, most procedures require overlapping multiple stents. Overlap zones create local increases in metal density and stiffness, producing focal stenosis, disturbed flow, delayed healing and higher thrombosis risk. They also further increase the duration of anticoagulation required. 

Fourth, conventional stents may shorten during deployment and after release, making precise positioning difficult. This can compromise inflow or outflow zones and increases the risk of migration. 

Taken together, these limitations explain why venous stenting still requires prolonged anticoagulation, has non-trivial rates of restenosis and migration, and often fails to fully restore physiological venous flow. 

ALTA was developed to address these root causes, not just their symptoms. 

How does the multi-segmented, variable geometry design differ from current venous stents? 

ALTA is based on a fundamentally different concept. The goal of venous stenting is not to create a rigid tube but simply to prevent vein collapse while allowing the vessel to retain its natural shape, taper and compliance. 

ALTA therefore uses discrete cell stent segments rather than a continuous tube. Each closed cell segment provides high radial force to keep the vein open, but the segments are connected by only three thin nitinol connectors. These connectors are intentionally too weak to impose geometry on the vessel. As a result, the vein dictates the shape of the stent rather than the stent forcing the vein into a straight line. 

Because the distance between the segments can be adjusted, the overall length of the stent is variable. A single ALTA device can be deployed across the entire iliofemoral tract, up to 24 cm, eliminating the need for overlapping stents and the complications that come with overlap zones. Tapering is built into the design so that the stent naturally matches the typical diameter transition from the iliac vein into the femoral system. 

Porosity is another major differentiator. ALTA is designed to have a very high effective porosity between segments and the closed cell segments itself also have a high porosity. This preserves side branch inflow and collateral outflow, increasing total venous flow through the limb. It also preserves far more viable endothelial cells immediately after implantation. Those cells retain their potent antithrombotic function and can rapidly grow over the struts. In a high porosity design, endothelialization is expected to be completed in roughly three months rather than the six to nine months typical of low porosity stents, reducing the duration of required anticoagulation.

Despite this high porosity, each closed cell segment delivers high radial force, so the vein remains open. Because the segments are independent, the overall device remains extremely flexible and conformable. 

Anchoring is provided by GripTech barbs on the proximal and distal segments, preventing migration without compromising flexibility or vessel conformity. 

How does ALTA’s length adjustable and tapered design improve anatomical fit? 

The segmental architecture and ultra thin interconnections mean that ALTA does not have the mechanical strength to straighten or distort the vein. This is critical. In real patients, forced straightening of veins by conventional stents can compress adjacent nerves and soft tissue, leading to pain and sometimes necessitating stent explantation. 

ALTA adapts to the patient’s anatomy rather than imposing a generic geometry. The tapered, adjustable length design allows precise matching of both diameter and length across complex iliofemoral anatomy using a single device, while maintaining full conformability to curves, angulations and changes in vessel calibre

What procedural advantages does this offer operators?

The primary procedural advantage is that only one stent is required to treat the entire iliofemoral segment. This simplifies inventory, eliminates the need for overlapping stents and removes one of the main sources of technical and biological failure.

Deployment requires some familiarization with the adjustable length concept, but once learned it provides far greater control over final stent length and positioning than fixed length devices. 

How might this architecture impact outcomes in complex lesions?

By eliminating straightening, preserving side branch flow, avoiding overlap zones, accelerating endothelialization and reducing thrombogenic metal burden, ALTA directly targets the mechanisms that drive restenosis, thrombosis and chronic symptoms after venous stenting. 

These features are expected to translate into higher patency, fewer re-interventions, improved symptom relief and a reduced need for long-term anticoagulation in complex iliac and iliofemoral disease.

You mentioned GripTech earlier. What key role do the barbs and engineered porosity play? 

GripTech barbs on the proximal and distal segments provide secure anchoring without requiring a rigid or traumatic design. This reduces the risk of migration while preserving flexibility. 

Engineered high porosity preserves endothelial viability, accelerates healing and improves both inflow and outflow through the stented segment. Together, these features support both mechanical stability and biological integration. 

What clinical data are being prioritized? And which patients might benefit the most? 

A first in human study is planned for Q1 and Q2 of 2026 to establish procedural safety, deliverability and early patency. This will be followed by a pivotal trial beginning in the first half of 2027 to formally demonstrate safety and effectiveness. 

The design is relevant to all iliofemoral venous obstructions, but its advantages are expected to be greatest in long, tortuous, tapered and anatomically complex lesions where conventional stents struggle most. 

Do you think anatomy adaptive stents will become the standard? 

Modular, anatomy adaptive venous stents represent the logical next generation of venous intervention. The theoretical advantages are compelling, but definitive evidence will come from prospective, head-to-head randomized trials. If these trials confirm the expected improvements in patency, symptom relief and reduced anticoagulation, this design philosophy is likely to become the new standard of care.