Cooled Microwave Denervation Catheter with Balloon Cooling
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Solution Overview
Problem
Current percutaneous renal denervation methods using RF energy damage the intima and media of the artery, leading to potential aneurism, atherosclerosis, and limitations in retreatment due to thermal injury risks, while existing cooled RF devices require electrical contact with tissue and are complex, and there is a need for a method that can provide complete circumferential thermal injury without damaging the artery walls.
Innovation Solution
A cooled microwave catheter system that uses a balloon to deliver microwave energy omnidirectionally, maintaining the intima and media of the artery at a safe temperature while heating targeted nerves to induce thermal damage, utilizing a microwave antenna optimized for renal denervation with adaptations such as modified antenna pitch and coil configuration to create precise SAR zones, allowing for controlled thermal ablation without damaging the artery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF energy is used to create focal ablation lesions in renal arteries, then renal denervation is achieved, but the intima and media of the artery are damaged leading to potential aneurism and atherosclerosis
Solution Approach 1:
The patent applies local quality by creating a temperature gradient where the adventitia and surrounding tissue are heated to ablation temperatures while the intima and media are actively cooled to protective temperatures. This spatial differentiation of thermal zones allows selective destruction of nerves in the adventitia while preserving the structural integrity of the intima and media through active cooling.
Solution Approach 2:
The patent implements preliminary anti-action by pre-cooling the intima and media with cold blood flow before and during the microwave ablation process. This proactive cooling creates a thermal barrier that prevents heat from propagating to the vulnerable arterial wall layers, counteracting the potential harmful thermal effects before they can occur.
2Object-affected harmful factors
If multiple discrete lesions are created in each renal artery to avoid arterial damage, then complete circumferential nerve ablation is attempted, but the procedure time is extended and nerve pathways cannot be completely eliminated
Solution Approach 1:
The patent merges multiple discrete ablation lesions into a single continuous circumferential ablation zone by using a microwave antenna that radiates energy omnidirectionally around the renal artery. This allows simultaneous creation of a complete 360-degree ablation band in the adventitia, eliminating the need for multiple sequential lesions and significantly reducing procedure time while maintaining arterial safety through selective thermal targeting.
Solution Approach 2:
The patent transitions from creating discrete point lesions to forming a continuous circumferential ablation zone by utilizing the radial dimension of microwave radiation. The microwave antenna generates a three-dimensional thermal field that envelops the renal artery, creating a continuous ablation band around the entire circumference rather than separate linear lesions.
3Object-affected harmful factors
If cooled RF devices are used to protect arterial walls, then thermal damage to intima and media is reduced, but the device complexity increases and electrical contact with tissue is required
Solution Approach 1:
The patent replaces the mechanical contact-based RF ablation system with a microwave radiation-based system. Instead of requiring electrical contact between an RF electrode and tissue, the microwave antenna generates electromagnetic fields that penetrate tissue and generate heat dielectrically. This substitution eliminates the need for complex electrical contact mechanisms while maintaining thermal control through blood flow cooling.
Solution Approach 2:
The patent changes the fundamental energy delivery parameter from electrical current (RF) to electromagnetic radiation (microwave). This parameter change allows for non-contact energy delivery and simplifies the device design by eliminating the need for electrical insulation and contact maintenance mechanisms required in RF systems, while achieving similar thermal ablation effects.
4Reliability
If discrete lesions are created at the same location along the artery length, then nerve pathways are blocked, but arterial weakening occurs leading to aneurism and possible rupture
Solution Approach 1:
The patent applies local quality by creating distinct thermal zones where the adventitia receives high-energy microwave radiation for nerve ablation while the intima and media are simultaneously protected by active cooling. This spatial differentiation allows complete circumferential nerve destruction without compromising arterial wall strength, as the vulnerable structural layers are maintained at protective temperatures throughout the ablation process.
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 system effectively denervates renal nerves while protecting the artery from damage, reducing the risk of aneurism and atherosclerosis, enabling retreatment and providing a shorter, more straightforward procedure by using microwave energy that does not require electrical contact with the tissue, thus ensuring the integrity and safety of the artery.
Implementation Method 1
a microwave antenna carried by the catheter, the microwave antenna being connectable to a microwave generator to supply power to the microwave antenna to cause microwave energy to be emitted omnidirectionally from the microwave antenna, thereby heating the tissue spaced from the body lumen to a temperature sufficient to cause thermal damage
Implementation Method 2
the tissue forming and adjacent to the wall of the body lumen are maintained at a temperature where thermal damage does not occur by virtue of circulation of cooling fluid in the balloon around the microwave antenna
Data Source
AI summary
A catheter is disclosed for creating a lesion in nerve-containing tissue spaced from a body lumen while protecting tissue forming and adjacent to a wall of the body lumen from injury. The catheter includes a catheter body having at least one fluid passage therein, a balloon in communication with the at least one fluid passage to receive cooling fluid for inflating the balloon, a microwave antenna carried by the catheter that emits microwave energy omnidirectionally, thereby heating the tissue spaced from the body lumen to a temperature sufficient to cause thermal damage while the tissue forming and adjacent to the wall of the body lumen are maintained at a temperature where thermal damage does not occur, and a tip structure located at an end of the catheter body, configured to receive a guide wire extending through the at least one fluid passage in the catheter body.