Guidewires are thin, flexible metal wires that play a crucial role in minimally invasive treatments. They guide the placement of catheters and other medical instruments in complex vascular systems through blood vessels. They are coated with hydrophilic guidewire coatings, a type of medical coating which helps ensure smooth and safe navigation. Hydrophilic coatings form a smooth, low friction layer on their surface when they are exposed to bodily fluids. This “slippery-when-wet” layer has high lubricity and wettability. This significantly reduces patient discomfort. It also prevents adverse reactions, such as thrombosis that lead to longer hospital stays and increased healthcare costs.
This guide provides an introduction to hydrophilic guidewire coatings. We will discuss what they are as well as cover their top benefits in radiology and cardiology procedures. At the end, we compare guidewires coated with hydrophilic and hydrophobic coatings. So you will want to make sure you read to the end.
If you are interested in this topic you will find our guide on Hydrophilic Coatings for Medical Devices very useful.
What are Hydrophilic Guidewire Coatings?
Hydrophilic guidewire coatings are surface modifications applied to guidewires. These coatings make the guidewire surfaces hydrophilic. Because they are water-loving they attract surrounding water molecules. As a result, they form hydrogels that have high lubricity and an extremely low coefficient of friction.
The main purpose of these coatings is to make the surface of the wire “slippery-when-wet”. This greatly reduces friction between the guidewire and the vessel wall. Reduced friction allows guidewires to more easily navigate through narrow areas and complex blockages.
Hydromer®, Inc. manufactures and supplies hydrophilic guidewire coatings to medical device manufacturers. These coatings help surgeons easily navigate through twisted or narrowed arteries. Coated guidewires reduce the risk of adverse reactions and complications. Improved insertion and movement throughout the patient’s body also ensures reduced discomfort and injury.
Components of a Hydrophilic Guidewire
Hydrophilic guidewires are composed of a core and an outer coating. We discuss each in more detail below.
Guidewire Core
The core of the guidewire is made of stainless steel or nitinol. Such materials enhance the strength and flexibility required to navigate through complex capillaries.
- Stainless Steel: Stainless steel guidewires are reasonably priced. They are durable and ideal for applications requiring high mechanical strength. Stainless steel also has excellent torque control and responsiveness compared to other guidewire core wire materials.
- Nitinol: Nitinol guidewires are more expensive due to their complex manufacturing processes. They have exceptional pushability, kink resistance, and flexibility. They are used in complex procedures requiring flexibility and softer torque response.
Guidewire Coating
The surface of the core (or wire) is coated with a hydrophilic guidewire coating. The coating covers the entirety of the guidewire surface. It plays a crucial role in the overall success and usability of a guidewire.
Below is a list of hydrophilic materials applied on the surface of guidewires:
- Hydrophilic Polymers: Polymer-based hydrophilic coatings are versatile. They have excellent properties, such as wettability, lubricity, and low friction. Hydromer’s medical coatings also exhibit critical properties, such as biocompatibility and thromboresistance.
- Some of the most popular hydrophilic polymers include poly(acrylic acid), polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), and polyethylene glycol (PEG).
- Hydrogels: Hydrogels contain 90% water entrapped in a three-dimensional, hydrophilic polymer network. A gel-like layer is created when hydrogels come in contact with surrounding liquids. Such a layer is extremely slippery when wet.
Top 5 Benefits of Using Hydrophilic Coatings for Guidewires
Hydrophilic coatings play a critical role in complex endovascular procedures. Some examples include navigating tight iliac or femoropopliteal lesions. Their water-attracting properties reduce vessel trauma. They also prevent endothelial damage, spasms, or dissections during delicate procedures.
Here are a few of the key benefits of hydrophilic guidewire coatings:
1. Excellent Lubricity Means Smooth, Rapid Movement
Lubricity is an important property when it comes to achieving smooth movement and navigation. It improves both the efficiency and safety of guidewires in medical procedures.
Hydrophilic coatings are activated in the presence of bodily fluids. The hydrophilic surface treatment attracts and retains moisture from the surroundings. This creates a thin layer that offers high lubricity and reduced friction. This is why they are referred to as “slippery-when-wet”. Hydrophilic guidewire coatings retain lubricity throughout the interventional procedure.
2. Decreased Trauma
Recovery time heavily depends upon the level of arterial damage caused by friction between the guidewire and artery walls. In many medical procedures, vascular trauma becomes a main reason for longer hospital stays.
In short, the risk of vessel damage or injury during such procedures should be minimized to the maximum possible level.
For this, hydrophilic guidewire coatings are helpful. They are used to reduce friction and improve safety during the procedure. This helps to reduce damage.
3. Improved Trackability
Hydrophilic coated guidewires are able to smoothly, and rapidly pass through convoluted vascular paths. When such coatings are exposed to moisture, they create a super slippery, gel-like surface. This reduces the friction between the guidewire surface and twisted or tortuous blood vessels. This low-friction feel inside the vessel improves trackability.
4. Greater Visibility
Advanced hydrophilic coatings are radiopaque. In other words, they block radiation and improve visibility under X-ray or fluoroscopy.
Why is this important?
The reason is that certain polymers and metal oxides absorb X-rays. They are combined with hydrophilic polymers to create radiopaque coatings. These coatings enable physicians enable physicians to track the location of the guidewire easily. As a result, the accuracy of catheter placement has increased significantly.
5. Enhanced Precision
Reduced friction, and improved navigation ultimately provide enhanced precision. This cuts down procedure time, increases the success rate, and speeds up patient recovery.
Medical instruments coated with Hydromer® hydrophilic medical coatings enable physicians to navigate smoothly with increased precision. This is extremely beneficial during interventional procedures like angioplasty and stent deployment.
Hydrophilic vs. Hydrophobic Guidewire Coatings
Hydrophilic and hydrophobic coatings are the most commonly used guidewire coatings in the medical industry. So which is better, and which should be used?
Here are the key differences that will help you decide the best choice for your guidewires.
| Attribute | Hydrophilic Coatings | |
|---|---|---|
| Purpose | Absorb water | Repel water |
| Lubricity | Excellent | Moderate |
| Navigation | Smooth even in convoluted vascular paths | Smooth across straight paths |
| Tactile Control | Due to high lubricity and slipperiness, handling the movements becomes challenging | Offers excellent movement control |
| Trauma | Drastically reduces the chances of vessel wall irritation | Compared to hydrophilic coatings, they have lower protection against vessel wall irritation |
| Applications | Medical procedures requiring easy navigation through complex vessel pathways | Best suited for less tortuous anatomy that requires precise control and push-ability |
Conclusion
High performance hydrophilic medical coatings are vital to the overall reliability and success of guidewires. These coatings help improve performance as well as patient outcomes.
Hydromer, Inc. is a medical coatings manufacturer with 40+ years of experience formulating and supplying customized hydrophilic medical coatings. Our company is focused on helping our customers improve the performance of their medical devices.
Our team includes highly qualified Ph.D. chemists, scientists, and regulatory experts. No matter what stage of the product development lifecycle you are in, we can help. You will get more than just a medical coatings supplier. Our capabilities span from R&D and regulatory consulting to contract coating and technology transfer. When you need a full-service partner, choose Hydromer.
Here is a quick list of contract services offered by Hydromer:
- Research and Development (R&D) services
- Contract coating services
- Specialized Analytical Testing
- Custom Machine Building
- Turn-key Operations
- Technology Transfer Services
- Technical consulting and support services
Contact our team of experts today to learn more about our services.
