Neurovascular microcatheters have transformed the treatment of patients around the world. They enable minimally invasive treatments in a challenging part of the body, so have significantly advanced healthcare in this field.
The range of neurovascular conditions that microcatheters are used to treat includes cerebral aneurysms, ischemic stroke, and other conditions that affect the vessels that supply blood to the brain and spine.
While there have been significant advances in the design and development of neurovascular microcatheters, there is a constant strive to push the boundaries of innovation, particularly in relation to the miniaturisation of catheter devices and components.
Further advances in miniaturisation reduce patient risk and trauma, and they enable the use of new medicines as well as new therapeutic and diagnostic technologies. As smaller and smaller microcatheters are developed, new types of treatment also become possible.
Navigating the Tortuous Vasculatures of the Head and Neck
A fundamental objective in most neurovascular microcatheter design projects is to make the outside diameter of the catheter as small as possible. This needs to be done while achieving the levels of performance required for the intended use of the catheter.
One particular performance objective that tops the list in many neurovascular microcatheter design projects is the ability to navigate tortuous and delicate blood vessels in the head and neck area. This is to ensure the catheter can reach the target treatment or diagnostic location, complete its function, and then be removed from the patient’s body, without causing trauma to blood vessels as it passes through.
Neurovascular Microcatheter Treatment and Application Examples
Different types of microcatheters can be designed for neurovascular applications, depending on the condition that is being treated. Cerebral aneurysms, for example, are often treated with occlusion balloon catheters. Stent delivery catheters, on the other hand, are often used to treat patients suffering from ischemic stroke.
Common applications for neurovascular microcatheter design projects include:
- Stent and graft delivery devices, including to the carotid artery
- Aneurysm coiling systems
- Embolization catheters
- Occlusion catheters and balloon catheters
- Catheters for thrombolytic treatments
Common Neurovascular Microcatheter Performance Characteristics
The performance characteristics typically required in neurovascular microcatheters include:
- Pushability to ensure the clinician can advance the catheter to the target treatment location.
- Effective torque from the proximal end to the distal tip, ensuring the clinician can effectively turn the distal tip.
- Steerability to ensure distal end responsiveness as the clinician navigates the catheter through vessels in the head and neck. Actuators such as pressure sensors, conducting layers, and other advanced technologies can enhance the steerability of microcatheter devices.
- Flexibility to enable the catheter to navigate through the complex blood vessels of the head and neck.
- Kink resistance.
- Visibility under fluoroscopy to assist clinicians during surgery.
- Pressure resistance to optimise the burst pressure rate, i.e., to ensure the catheter shaft doesn’t burst.
- Compression resistance to ensure the catheter shaft maintains its shape.
- Delamination resistance to prevent the separation of the catheter’s layers (liner, braid and/or coil reinforcement layer, and the outer jacket).
Three Essential Layers
A neurovascular microcatheter will typically have three main layers, with the objective being to minimise the thickness of each layer as much as possible while retaining the required performance characteristics. The three layers include:
- Ultra-thin shaft walls, often comprising a combination of different polymers
- Lubricious liners, often achieved by using PTFE
- Reinforced shafts
The materials used in each of the three layers are crucial to performance, so material science is an essential part of neurovascular microcatheter design.
In terms of achieving the desired performance characteristics while minimising the outer diameter of the shaft, the type of reinforcement that is used is critical.
The reinforcement techniques that are typically included in neurovascular microcatheters are braid reinforcement, coil reinforcement, or a combination of both. Furthermore, the design of the reinforcement can vary along the length of the shaft to optimise performance.
For example, using a combination of braid and coil reinforcement and varying this along the catheter’s shaft can achieve the desired levels of stability, flexibility, and radial strength.
Working With an Experienced Partner
Given the complexity and level of detailed knowledge that is involved in the development of neurovascular microcatheters, it is important to work with a design partner with the right expertise. To speak to one of our design engineers about your project, please get in touch.
