By Sunil Inamdar, Vice President of Technical Development, Polyzen
Specialized, custom-shaped low-pressure balloons are commonly used in gastrointestinal, cardiovascular, and/or drug delivery applications, among others. Why use low-pressure balloons? Perhaps their biggest benefit is that they have the flexibility to stretch over 600% of their predetermined diameter. This expansion profile, paired with high durability, enables low-pressure balloons to fill and create spaces, deliver drugs, and enable proper positioning.
The ability to design balloons with custom geometric conformation enables medical device designers to create products specifically for intended applications rather than designing around the restrictions of manufacturing traditional high-pressure balloons. Low-pressure balloons are especially useful for designing custom shapes to fill uniquely shaped cavities in the body; this is because they do not retain well-defined shapes. This freedom also allows designers to customize how the balloon is attached to the broader device, enabling previously unattainable geometries and neck-to-body ratios.
Procedures Utilizing Low-Pressure Balloons
Low-pressure medical balloons are used in various procedures and catheter applications, including:
- Cardiovascular
- Fixation: To fix the position of a catheter in a vessel
- Occlusion of blood flow: To seal off a vessel
- Cardioplegia balloons: To facilitate temporary heart arrest during surgery
- Drug delivery through a semi-porous membrane
- Tumor treatment (brachytherapy): Used in targeted radiation for tumor treatment
Catheter Applications Utilizing Low-Pressure Balloons
- Embolectomy/thrombolytic catheter balloons
- Esophageal balloon
- Heart valve and thermodilation
- Minimally invasive bypass surgery
- Port-access
What is Balloon Compliance?
When evaluating balloons, medical device designers must understand the concept of compliance. Compliance refers to how much a balloon will stretch beyond a predetermined diameter under an applied force. Low-pressure balloons are considered compliant. This means that increased pressure will expand the balloon in areas of low resistance in the balloon and in the body.
High-pressure, or “non-compliant” balloons, will not stretch beyond a predetermined diameter. Non-compliant balloons maintain their profile and shape with repeated inflations and can rupture before permanently deforming. An overview of the compliance scale is outlined below:
- A low-compliance, high-pressure balloon expands 5-10% beyond a predetermined diameter.
- A high-compliance, high-pressure balloon expands 18-30% beyond a predetermined diameter.
- A low-pressure balloon can stretch 100-600% and recover close to its original size; however, it cannot tolerate high pressures.
In addition to application and compliance, material selection is a key component of designing and developing a low-pressure medical balloon. Traditionally, latex balloons have been considered the standard for medical device applications. However, alternatives to latex must be considered when constructing low-pressure balloons, given the commonality of latex allergies and the superior properties offered by other materials such as polyurethane. Polyurethane has emerged as an excellent alternative for latex, which can be thermoformed and welded together to form a medical balloon that achieves previously unattainable neck-to-body ratios. Polyurethane is accessible and can be processed quickly, allowing for medical device designers to iterate with designing and prototyping.
In addition to polyurethane, thermoplastic elastomers can be used to create more flexible balloons. Silicone is also an excellent material for dip molding low-pressure balloons, as it can stretch up to 1000% of its original position and demonstrates excellent strength. Both thermoforming and dip molding are viable solutions for producing low-pressure balloons, depending on material selection and balloon requirements.
Thermoformed balloons are fully 3-dimensional and exhibit a nearly invisible seam on the inside of the balloon, making them ideal for in-patient applications. Using the thermoforming process, low-pressure balloons can be produced in almost any size and configuration, ranging from as small as 0.200” with neck-to-body ratios of 1:5, 1:10, and 1:20, depending on the material. These polyurethane balloons are compact and easily foldable, providing an easier insertion compared to traditional latex balloons. Various thicknesses are achievable depending on the designer’s application and requirements. These balloons offer more versatility compared to other non-latex, low-pressure alternatives that are limited by 2D forms and extremely low-pressure tolerances.
 Thermoformed Balloons |
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Dip-molded Balloons
Dip molding is another method for creating custom, low-pressure balloons. The dip-molding process uses a polymer solution to create seamless, hollow balloons by dipping a mandrel into the solution, baking off residual solvent, and demolding the mandrel. Dip-molded balloons can be made of polyurethane, silicone, fluoropolymers, and bioabsorbable polymers, among other materials, which opens the process for a wide range of applications. Given the lack of seam, dip-molded balloons are ideal for in-patient applications like gastrointestinal balloons, which must be seamless to avoid tearing/rubbing inside the patient’s stomach.
Develop Low-pressure Balloons with Confidence
Medical device manufacturers have a variety of methods and materials to consider when designing low-pressure medical balloons for gastrointestinal, cardiovascular, and drug delivery applications, among others. Thermoforming and dip molding have emerged as two reliable and repeatable methods for creating these critical medical device components, which can be customized for optimal construction for deployment, durability, strength, and thickness.
Device manufacturers should partner with an experienced medical balloon manufacturer that can match the right materials to the appropriate design and development processes to ensure that polymer-based devices or components meet specified performance criteria to ultimately impact patient care.
To explore polymer-based medical device and component solutions, visit www.polyzen.com.
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