When it comes to the cardiovascular procedures, small is indeed beautiful. With the need for minimally invasive procedures and increasing moves to deliver therapies to hard-to-reach areas such as the brain, miniaturization is a niche that demands significant focus. Procedures are rapidly changing, creating a need for new technologies that can help address unmet needs. Nevertheless, as with all medical devices, the proof is in the application, and this requires supporting evidence pointing to successful outcomes.

Small and ultra-small peelable heat shrink tubing is enabling new levels of miniaturization for catheters and guide wires to address these unmet needs. This miniaturization is also paving the way for peelable fluoropolymers that can be used in applications such as improving safety for catheter construction. Overall, peelable heat shrink tubing (PHST) is a direct answer to the medical device industry's call for quicker and more efficient processes, without compromise to the overall product integrity.

When manufacturing catheters, for example, fluorinated ethylene propylene heat shrink tubing (FEP-HST) is typically welded, laminated, or tipped, to create required features. However, removing FEP-HST can cause problems in catheter manufacturing. The only way to remove this material is by ‘skiving,’ using a customized tool, which takes considerable time and effort and increases the possibility of damaging the catheter (see Figure 1).

Fig. 1 - Removing FEP-HST takes considerable time and effort and increases the possibility of damaging the catheter. By contrast, PHST can be removed simply using a 10-mm pre-slit on one end of the tube.

By contrast, PHST can be removed simply using a 10-mm pre-slit on one end of the tube. In recent years, PHST has been used successfully to weld polyamide in the manufacture of catheters and guide wires. Figure 2 shows typical applications.

Taking PHST to the Next Generation

Two families of ultra-miniature PHST products developed by Junkosha are aimed at helping make microsurgical procedures safer, more precise, and less invasive. The ultra-small PHST and high-shrink ratio PHST products are intended primarily for use in miniaturized microcatheters and guide wires and are designed to help enable access to the most exacting parts of the vasculature with minimal impact on the patient.

Fig. 2 - A splitting tool facilitates the removal of PHST.

Ultra-small PHST offers a recovered ID as low as 0.009 in., meaning it can be used as a laminated jacket coating for tiny guide wires, typically between 0.011 and 0.014 in. The resulting miniature guide wires are well suited for procedures that navigate tiny vessels to reach a lesion or vessel segment within, for example, the brain or heart. Moreover, the high-shrink ratio PHST (2:1) makes it ideal for manufacturing processes where tapered microcatheter shafts are used or where tolerance take-up is an issue.

These PHST products support the development of the next generation of precision engineered, miniaturized microcatheters and guide wires. As medical professionals push the boundaries of what they require for minimally invasive procedures, this ultra-small tubing offers a pathway to miniaturized medical technology future.

Miniaturization Paves the Way for the Future

The trend toward miniaturization of catheters covers a wide spectrum of applications including neurovascular delivery of devices such as coils and stents for stroke or aneurysm therapies and even to deliver signals or energy to help support treatments such as neuro-modulation or neurostimulation for the treatment of Parkinson's disease. These developments are paving the way for further innovations in the field of active catheters, which are designed to provide conduits for the delivery of signals or energy such as intravascular ultrasound (IVUS). This technology is used for diagnostic applications such as intravenous examination of atherosclerosis, a condition in which fatty material collects along the walls of arteries, with the distal end providing signals back to data collection equipment. Alternatively, therapeutic applications involve pulsed ultrasound to remove plaque, and a transcranial MRI-guided high-intensity focused ultrasound (HIFU) system for the non-invasive treatment of various brain diseases such as brain cancer and Parkinson's disease (thermal ultrasound) and stroke (mechanical ultrasound using microbubbles). 1

Peripheral artery disease (PAD), where plaque builds up in arteries in the legs and in other places preventing blood flow, is usually treated using balloon angioplasty and stents, if a procedure is called for. A new device, pioneered by Fremont-based Shockwave Medical, combines lithotripsy — which uses sound waves to break up calcium and is often used to treat patients with kidney stones — with the commonly used angioplasty balloon catheter. The Lithoplasty System was cleared by FDA for use in the treatment of PAD in the United States, where one in 20 individuals over the age of 50 has PAD. 2

Microcatheter Future and Miniaturization

An approach developed by Junkosha is supported by Robert LaDuca, CEO of Duke Empirical, Inc., a medical device manufacturer, who explains: “As medical technology advances, device designers worldwide are being challenged to produce smaller and thinner microcatheters and guide wires that provide clinicians with the ability to reach and treat previously inaccessible anatomical targets. The extension of minimally invasive treatment options for previously untreatable patient populations has created a need for new tools used in catheter manufacturing, such as the peelable heat shrink tubing. In our experience, these new tools have been cost-effective in reducing scrap rates while increasing throughput by shortening assembly time.

“In addition, these new products enable the manufacture of products that previously would not have been possible due to the challenges of heat shrink removal from delicate soft polymers used in certain high-performance catheters,” continues LaDuca. “In the future, we anticipate the utilization of miniaturized catheter solutions will be widely adopted by most medical manufacturers working on the leading edge of microcatheter technology.”

In general, smaller FEP-HST tubing is more difficult to remove. Ultra-small PHST tubing (less than 0.25 mm recovered ID) is easy to skive away because of its peelability. If it is difficult to make a slit in the center of the tube at the peeling end, the splitting tool provides the complete solution (see Figure 3).

Future Proofing

Fig. 3 - A splitting tool facilitates the removal of PHST.

The medical device industry is driving tubing manufacturers to investigate applications, review customers unmet needs, and innovate new products and solutions in order to deliver therapies to hard-to-reach areas, and in some cases the delivery of nanotechnology synthesized medication in, for example, cancer treatments.

Understanding these roadmaps and how they are being led by clinicians is critical. It is only by understanding how they are being challenged that the technology can be tailored to address the need. Suppliers must embark on a new or unexplored path requiring fresh, innovative approaches. This is, in effect, is what is referred to as discontinuous innovation — or the popular buzzword disruption — whereby suppliers seek to effect a paradigm shift in science or technology and/or the market structure of the industry. It takes a certain type of organization to have the courage to continuously push the boundaries. That means learning by doing, sorting, and sifting through what works and what does not to produce an optimized solution that is robust and provides real added value to the customer.

In order to lead this category, it is imperative to pioneer and innovate. It is also essential to be acutely aware of costs. In the United States, for example, where healthcare is 20 percent of the total spend, the pressure is on to reduce costs. U.S. healthcare spending is projected to rise 5.3 percent in 2018, reflecting rising prices of medical goods and services and higher Medicaid costs, and an upward trend is forecast for the next decade. This increase represents a sharp rise from 2017 spending, which the U.S. Centers for Medicare and Medicaid Services (CMS) now estimates to have been a 4.6 percent climb to nearly $3.5 trillion. 3 If nothing else, this places a huge focus on efficiency of processes and that's where innovation can play an important part.

Overall, a successful approach and market strategy is to provide to customers a reduced total cost of ownership. This is predicated by the successful supply chain partner ticking some vital boxes, namely: time, efficiency, yield, and reduction in number of processes. Junkosha looks at this continuously as the company gauges the impact and value of its product offerings. With costs always in mind, a healthy strategy is to help customers and end users maintain outcomes, while delivering value. This is not an easy journey since companies must at the same time meet the ongoing push toward shorter product life cycles and global supply chains.


The increase in minimally invasive procedures and advances in technologies to deliver therapies to hard-to-reach areas such as the brain has driven the need for miniaturization. Small and ultra-small peelable heat shrink tubing is enabling new levels of miniaturization for catheters and guide wires to address these unmet needs. The ultra-small PHST and high-shrink ratio PHST products are for use in miniaturized micro-catheters and guide wires, which are designed to help enable access to the most exacting parts of the vasculature with minimal impact on the patient.

This article was written by Joe Rowan, President and CEO, United States and Europe, Junkosha, Tokyo, Japan. For more information, visit here .

Medical Design Briefs Magazine

This article first appeared in the June, 2018 issue of Medical Design Briefs Magazine.

Read more articles from this issue here.

Read more articles from the archives here.