In order to identify the location of a catheter tip under fluoroscopy, the use of marker bands is commonplace in medical applications. These bands are typically platinum iridium metals that are easily detectable on the technology used during the surgeries but can also be made of tantalum or gold for certain applications. The marker bands are put on the catheter, either through swaging or embedding, as a shiny indicator to the surgeon of directly where in the body the tip is located as the operation progresses.

The significant difference between these two methods of how the marker band is adhered ultimately impacts the failure or success of the product, which begins at the development phase.

The development team behind the product design identify the need for a catheter with this marker band on the tip and begin the prototyping process. They bring the design to a contract manufacturer or the engineers responsible for bringing the design to life, who are faced with two options — swage the marker band on or embed it in the tip. This is a pivotal choice in the success of the product’s end use.

What Are the Differences Between the Two?

Swaging a marker band onto the tip has been the default choice for designs of this caliber. This method of adhesion is performed using a swaging machine with a special die that essentially hammers the marker band onto the extrusion. It is mechanically bonded onto the tip but is still exposed on the outer diameter.

Embedding a marker band into the tip is newer technology that is not always considered during development but has recently become more popular. This technique uses radiofrequency (RF) energy to physically flow the plastic around the marker band, totally encapsulating it within the extrusion wall. The marker band is not exposed to the inner nor outer diameters; it is completely within the extrusion.

After adhesion to the tip by either method, the physical result in terms of process development is expected to be the same — the marker band stays on the tip during the procedure. Specialized dies and tooling must be designed for both options, the cycle time per process is roughly equivalent, and they both require ownership of respective equipment, such as a swaging machine or RF generator. The upfront cost of this development for choosing to embed the marker band is slightly higher than swaging, but the ultimate cost of possible failure that results from swaging outweighs the upfront costs.

Success vs. Failure

Swaging can be a viable option for many manufacturers but because of the nature of swaging, there is a chance of failure in the field. The marker band is hammered mechanically onto the catheter, but it is still exposed. This can make the surface uneven on an inherently lubricious shaft, providing the unfortunate possibility of a slightly angled marker band to cut into an arterial or venous wall during surgery. An improperly swaged marker band can even fall off altogether inside the body as discussed earlier, which has been viewed under fluoroscopy and infamously deemed a “shooting star.”

When embedding a marker band, neither of these damaging failures are possible. The marker band is encapsulated in the extrusion entirely, which allows for no dislodging. The surface of the catheter is smooth to the touch so there are no sharp edges to damage the inside of the body with. Fluids or other necessary devices are free to travel through and around the catheter as desired.

As newer technology becomes available, the use and adhesion of marker bands in the medical field will continue to evolve into more effective, superior methods. It is the responsibility of engineers to incorporate these techniques into the processes of their contracted medical products to make them better. The lives of patients everywhere depend on it.

This article was written by Ariana Boyden, Technical Writer for Pelham Plastics, Pelham, NH. For more information, visit here .


Medical Design Briefs Magazine

This article first appeared in the June, 2020 issue of Medical Design Briefs Magazine.

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