How a professional CMO can turn catheter design intent into scalable, verifiable, and traceable manufacturing performance.

Structural heart intervention continues to expand, and China’s occluder market has reached a significant level of clinical adoption. In 2025, approximately 143,000 congenital heart defect occluders were implanted in China, with atrial septal defect (ASD) and patent foramen ovale (PFO) devices accounting for the largest share. During the same period, annual transcatheter left atrial appendage (LAA) closure procedures exceeded 31,000, with more than 700 medical centers performing the therapy.

Rising procedure volumes are increasing demand not only for the implants themselves, but also for delivery sheaths, dilators, loaders, and deployment components. Whether the procedure involves an ASD, ventricular septal defect (VSD), patent ductus arteriosus (PDA), PFO, or LAA occluder, the implant ultimately closes the defect or isolates the target anatomy. The delivery system, however, determines whether the device can reach the intended site, deploy predictably, be released accurately, and, when required, be retrieved and repositioned.

For occluder manufacturers, the real challenge is rarely whether a single functional delivery sheath can be produced. The difficulty becomes apparent when a project moves from prototype validation to pilot production, clinical registration, and commercial-scale supply.

Why does the distal curve vary from unit to unit? Why does the sheath kink or lose lumen integrity along a tortuous path? Why do defects repeatedly occur during distal forming, flaring, bonding, welding, or at loader transition interfaces?

As a CMO specializing in precision interventional catheter manufacturing, Shanghai Eco Polymer views the core challenge as an engineering translation process: transforming an experience-dependent prototype into a manufacturing process that is verifiable, traceable, and reproducible at scale.

1. Why Are Occluder Delivery Systems So Difficult to Manufacture?

From a manufacturing perspective, a complete occluder delivery system can generally be divided into four component groups: the delivery sheath or delivery catheter, the dilator, the loader, and the delivery or release mechanism. The exact definition of the “system” may vary among device manufacturers.

For an upstream catheter manufacturer, the objective is not to replace the customer’s implant design capabilities. Instead, it is to translate the clinical requirements of the delivery sheath, dilator, and related catheter components—particularly the need to establish a safe and reliable access pathway—into structures and processes that can be manufactured consistently.

Challenge 1: Balancing Flexibility, Support, and Kink Resistance

Different closure procedures impose different performance requirements on the delivery system.

ASD and PFO occluders generally require a low-profile system, distal flexibility, and controlled deployment. Although the PFO opening itself is often small, the occluder discs may cover a relatively broad area. The system must therefore minimize its outer diameter while maintaining stable loading, advancement, retrieval, and deployment performance.

VSD and PDA closure procedures may involve more variable access routes, defect locations, and anatomical conditions. Their delivery systems typically require greater support, kink resistance, lumen stability, and smooth advancement.

LAA closure places broader demands on coaxial alignment, directional control, distal pre-shaping, and controlled deployment. Torque response, kink resistance, and flexible transitions are therefore particularly important.

An occluder delivery system is neither “the stiffer, the better” nor “the softer, the safer.” The proximal section must provide sufficient support for advancement and control, while the distal section must remain flexible and atraumatic, with smooth transitions and stable dimensions to support controlled deployment at the target site.

Challenge 2: Combining a Low-Friction Lumen with Stable Inner Diameter

During loading, advancement, retrieval, and deployment, the occluder is compressed, advanced through the delivery system, expanded, and potentially repositioned. A lumen that meets dimensional specifications during static inspection does not necessarily provide smooth and consistent functional performance under simulated-use or clinical-use conditions.

Liner lubricity and adhesion, inner-diameter consistency, wall-thickness uniformity, and surface quality all directly affect release force and physician handling.

Excessive internal friction may increase advancement resistance. If the inner diameter changes when the catheter is bent, device passage may become inconsistent, deployment may become less predictable, and the operator may have greater difficulty identifying critical release points.

In volume production, these issues rarely result from a single out-of-specification dimension. More often, they are caused by the combined effects of raw-material lot variation, multilayer construction, thermal processing, liner surface condition, and secondary operations.

Challenge 3: Distal Engineering for Access, Positioning, and Safety

The distal section is the part of the delivery system closest to the intracardiac anatomy and is a major determinant of procedural handling.

In LAA closure, distal curve geometry and coaxial alignment influence how effectively the physician can align the system with the appendage ostium. For congenital occluders, flexible transitions, flared ends, radiopaque marker placement, and stable connection interfaces also affect device passage, expansion, and deployment.

Distal construction may involve tip forming, flaring, pre-shaping, radiopaque marking, welding, edge rounding, bonding, or hydrophilic coating.

During prototyping, experienced operators may manually adjust individual units. Once a product enters pilot and volume production, however, curve springback, flare dimensions, weld strength, step-offs at transition zones, and surface burrs become critical sources of lot-to-lot variation.

In many cases, the difference between an acceptable delivery system and a consistently reliable one is not whether the shaft can be extruded. It is whether these seemingly minor distal features can be controlled consistently across every production lot.

2. The Role of a Professional CMO: Converting Uncertainty into a Controlled Process Window

A professional CMO should be more than a build-to-print supplier. It should serve as an engineering partner capable of translating the customer’s design intent into a manufacturing pathway that can be scaled up, verified, and traced.

For an occluder delivery system, Shanghai Eco Polymer provides more than tubing or manufacturing capacity. The objective is to create manufacturing certainty through coordinated control of structure, materials, processes, and inspection.

From Dimensional Compliance to Reproducible Functional Performance

During development, teams often focus on whether the final dimensions meet the drawing requirements. At commercial scale, however, the more important question is whether the same process can consistently reproduce pushability, kink resistance, torque response, and deployment feel across different production lots, shifts, operators, and raw-material batches.

・Material-system matching: Select the liner, reinforcement layer, outer jacket, and durometer gradient based on the customer’s functional targets, rather than simply combining available materials.

・Reinforcement process window: Establish a stable balance between support and flexibility through braid or coil architecture, wire specifications, reinforcement density, reinforcement length, and transition design.

・Thermoforming consistency: Establish a predictable and verifiable process window for controlling shrinkage and springback during distal pre-shaping, flaring, and tip-forming operations.

From Subjective Handling Feedback to Data-Based Verification

Many delivery-system issues are described during clinical or simulated use as an “inconsistent feel.” Production-scale quality control, however, cannot rely on subjective handling feedback alone.

The variables behind that feel must be decomposed into measurable and traceable critical quality attributes.

・Dimensions and construction: Outer diameter, inner diameter, wall thickness, concentricity, effective length, distal curve angle, flare dimensions, and radiopaque marker position.

・Mechanical and handling performance: Kink resistance, pushability, torque response, release force, retrieval smoothness, and distal transition flexibility.

・Process and reliability: Thermal bond strength, weld strength, hydrophilic coating performance, delamination risk, surface burrs, particulate control, and performance drift after aging.

・Validation and traceability: Appropriate process validation, lot traceability, and inspection records to support regulatory submissions, supplier audits, and commercial-stage quality management.

3. You Define the Performance Target; Shanghai Eco Polymer Builds the Manufacturing Path

In structural heart occlusion, a device company’s core differentiation often comes from implant design, release-mechanism architecture, anatomical compatibility, and physician experience.

Entrusting the precision manufacturing and consistent supply of delivery sheaths, dilators, and related catheter components to a specialized CMO is therefore more than an outsourcing decision. It is a practical way to reduce uncertainty between product development and commercial production.

If your team is developing or upgrading an ASD, VSD, PDA, PFO, or LAA closure system, Shanghai Eco Polymer welcomes the opportunity to discuss your structural, material, process, and performance requirements.

Conclusion: Reliable Access, Predictable Deployment

The occluder closes the defect or isolates the target anatomy—but the delivery system determines how safely, smoothly, and predictably it gets there.

As structural heart intervention continues to grow, competition among occluder manufacturers is no longer defined by implant design alone. Delivery-system performance, material and process engineering, and scalable manufacturing capabilities are becoming increasingly important.

Shanghai Eco Polymer’s objective is clear: to move occluder delivery-system manufacturing from an experience-dependent prototype that is merely functional to a data-driven, stable, and reproducible commercial process.