Microwave Ablation Catheter with Independent Sensing
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Solution Overview
Problem
Current radiofrequency ablation techniques are limited in creating deep ventricular lesions due to the attenuation by epicardial fat and the presence of coronary arteries, leading to insufficient lesion depth and potential tissue overheating.
Innovation Solution
The use of a microwave ablation device with a specially designed catheter that includes a microwave radiation antenna, an independent electrical sensing system, and a septated lumen structure to facilitate fluid flow and electrical sensing, allowing for deeper and more controlled tissue ablation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If radiofrequency ablation is used to create deep ventricular lesions, then the catheter can be inserted via vasculature to target VT circuits, but the lesion depth is insufficient (maximum 7mm) due to thermal conduction limitations and epicardial fat attenuation
Solution Approach 1:
The patent replaces radiofrequency thermal conduction with microwave electromagnetic radiation to achieve deeper tissue penetration. Microwave energy directly heats tissue at greater depths without relying on thermal conduction from the catheter surface, overcoming the 7mm depth limitation of RF ablation and enabling reliable targeting of deep arrhythmogenic substrates in the ventricular myocardium.
Solution Approach 2:
The patent changes the energy delivery parameter from radiofrequency (lower frequency) to microwave (higher frequency) to alter penetration depth characteristics. This parameter change enables the energy to penetrate through epicardial fat and reach deeper ventricular structures, transforming the ablation capability from surface-limited to depth-capable.
2Volume of stationary object
If higher radiofrequency energy is delivered at higher contact forces to generate larger lesions, then lesion size increases, but tissue overheating occurs leading to steam pops, ventricular perforation and systemic embolism
Solution Approach 1:
The patent substitutes microwave energy for radiofrequency energy to achieve more uniform volumetric heating. This replacement allows larger lesion volumes to be created without the excessive surface heating that causes steam pops and perforation, as microwave energy distributes thermal energy more evenly throughout the target tissue volume rather than concentrating it at the catheter-tissue interface.
Solution Approach 2:
The patent employs pulsed microwave delivery with intermittent cooling periods to prevent tissue overheating. By delivering energy in controlled pulses rather than continuous exposure, the system accumulates therapeutic lesion volume while allowing heat dissipation between pulses, preventing steam pop formation and vascular injury.
3Length of stationary object
If radiofrequency ablation is performed in the epicardium to overcome lesion depth limitations, then deeper substrate can be targeted, but epicardial fat attenuates resistive heating and coronary arteries limit safe ablation sites
Solution Approach 1:
The patent changes the energy frequency parameter to microwave, which penetrates epicardial fat more effectively than radiofrequency energy. This parameter change removes the attenuation barrier posed by epicardial fat, enabling ablation at any epicardial site regardless of fat thickness, and significantly increasing the versatility and adaptability of available ablation locations.
Solution Approach 2:
The patent replaces contact-dependent radiofrequency heating with non-contact microwave radiation. This substitution eliminates the need for direct catheter-tissue contact and overcomes the limitation of coronary arteries blocking safe ablation sites, as microwave energy can be delivered through the catheter wall and heat tissue at a distance, providing greater adaptability in selecting ablation locations.
4Manufacturing precision
If microwave ablation is used to debulk left ventricular outflow tract in hypertrophic obstructive cardiomyopathy, then a more predictable and safer septal lesion can be produced, but the conduction system must be protected from injury to avoid pacemaker implantation
Solution Approach 1:
The patent applies microwave energy with localized targeting to create precise lesions in the hypertrophied septum while sparing the conduction system. By controlling the microwave field distribution and duration, the system produces predictable tissue ablation in the target region while the moving conduction system structures are less likely to be permanently damaged, maintaining conduction system integrity and reducing pacemaker requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The microwave ablation device effectively creates deeper and larger lesions compared to radiofrequency ablation, while minimizing the risk of coronary artery injury and tissue overheating, thus providing a safer and more effective treatment for ventricular arrhythmias.
Implementation Method 1
microwave energy applied in the right way can also penetrate epicardial fat, sparing coronary arteries (because of arterial blood flow) and therefore minimising the potential for arterial injury
Implementation Method 2
The inventors have determined that endocardial microwave catheter heating can overcome these limitations by providing the ability to directly heat a larger volume of myocardium
Implementation Method 3
an outer sheath encasing the radiating element, and includes perforations at the distal end of the catheter to enable (1) open irrigation (including cooling function)
Implementation Method 4
the electrical sensing system includes an electric circuit which incorporates an ionic conductivity bridge formed between said one or more metal electrodes and the fluid exiting said one or more orifices
Implementation Method 5
Microwave energy applied in the right way can also penetrate epicardial fat, sparing coronary arteries
Implementation Method 6
sparing coronary arteries (because of arterial blood flow) and therefore minimising the potential for arterial injury
Data Source
Figure 1
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AI summary
The invention relates to an ablation device for delivery of microwave energy to a selected region of tissue, in particular for producing deep endocardial or epicardial ventricular lesions, such as for the treatment or prevention of arrhythmias. The device includes a microwave radiation antenna electrically connectible via a microwave feedline to an electrical microwave system, the microwave antenna configured to generate a microwave field able to ablate tissue in said selected region of tissue, the antenna positioned within an antenna-receiving portion of an elongated catheter configured to allow fluid flow along the catheter to exit through one or more orifices in the catheter wall, the catheter provided with an electrical sensing system including one or more metal electrodes and being independent of the electrical microwave system, the device configured such that in use the electrical sensing system includes an electric circuit which incorporates an ionic conductivity bridge formed between said one or more metal electrodes and the fluid exiting said one or more orifices, the ionic conductivity bridge traversing said catheter antenna-receiving portion.