The journey towards intelligent catheters
The journey towards ‘intelligent catheters’ is an important one. In order to advance surgery, it is crucial to have smaller, more flexible and higher capacity catheters at your disposal. Solutions such as Multi-Filar and Multi-Channel Transmission (MCT) represent a breakthrough in the design of medical device cables that take us one step closer on the journey to the next generation of these important devices.
Multi-Filar active catheter solution
Multi-Filar cables have a capacity of up to 60 power lines – depending on AWG size or pitch – and are designed to provide not only increased functionality but also more signals into formerly inaccessible areas of the body.
Using precision-engineered PTFE lamination technology, single strand configurations are joined into a Multi-Filar assembly that can be utilised in electrophysiology catheters for applying pacing and recording protocols from inside the heart, ablation and balloon ablation catheters for atrial fibrillation as well as cardiac mapping.
The Multi-Filar technique also allows for easier assembly of the signal or power wires into the final medical device, making the manufacturing process simpler and more cost-effective.
The bond strength between the individual strands can be adjusted to maximise strength for challenging assembly conditions or optimised for difficult separation processes. Multi-Filar configurations allow for joining dissimilar single strand alloys together in one package, which is perfectly suited for applications like thermocouples, micro-cables that need a high strength member for load bearing, or assembly operations and electrochemical process cells.
MCT cables are a further milestone towards intelligent catheters. MCT represents a significant improvement on existing twisted pair coaxial and flexible printed circuit technology and enables new data-rich signals to be utilised in therapies such as intracardiac echocardiogram, ultrasound endoscopy and IntraVascular UltraSound (IVUS).
Existing catheters use twisted pair coaxial constructs to support signals along the device. This established technology has driven advances in catheter design and facilitated the delivery of many essential interventional, intervascular diagnostics and therapies. However, both progress of miniaturisation and flexibility has been hampered by the standard coaxial approach which comprises a core conductor, insulation, and a shield wire. Physics and electromagnetics have prevented the development of smaller cables and has inhibited catheter flexibility.
In contrast, the new MCT cable design uses a cluster of simple microwires that are individually insulated with an innovative shielding/grounding construct which employs flux cancellation, therefore, increasing its signal capacity for a given size. Whilst the traditional catheter requires two coaxial cables to run in parallel carrying two individual signal streams, MCT enables multiples of four signals to be brought together in one cable, therefore, significantly increasing the signal capacity per unit diameter.
Early prototypes have achieved a 32% reduction in the size of the cable, a critical factor in the attainment of future procedures within narrower vessels. The MCT approach also provides a greater degree of flexibility compared to the existing approaches which promises major advances in the scope of medical procedures, especially within endoscopy. Importantly, MCT addresses the mutually exclusive needs of small size and signal integrity simultaneously.
Looking further forward into the future, the next steps will likely focus on improved imaging. One route for this is through equipping catheters with an optical fibre containing tiny “mirrors” that reflect light when it passes through. When the fibre bends, sensors can detect any change of colour in the reflected light which provides information on the intensity and direction of the curvature1, thus enabling more precise navigation. A prototype of this system is due later this year.