Microwave Ablation Device with Unbalanced Radiator and Irrigation Cooling
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Solution Overview
Problem
Existing radiofrequency catheters for renal artery denervation often cause unintended injury to the renal artery, reducing efficacy due to their tendency to damage the full thickness of the artery before affecting the nerves, which can lead to renal artery stenosis and inadequate blood pressure reduction.
Innovation Solution
A microwave ablation device with an unbalanced radiator and irrigation system that uses a conductive core extending to the radiator, insulated from its environment, allowing for circumferential thermal ablation of renal nerves while sparing the renal artery wall through arterial blood flow and irrigation fluid cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radiofrequency catheters perform ablation to destroy renal nerves, then denervation efficacy is improved, but the renal artery wall is injured causing stenosis
Solution Approach 1:
The microwave radiator is designed to create a non-uniform heating pattern where the energy is concentrated at greater depths (adventitia layer) while the luminal surface remains cooler. This local quality differentiation allows effective nerve destruction in the outer layer while preserving the arterial wall integrity.
Solution Approach 2:
Irrigation fluid is introduced as an intermediary cooling medium between the microwave radiator and the renal artery luminal surface. The irrigation fluid absorbs excess heat and prevents thermal injury to the arterial wall while allowing effective ablation of the renal nerves in the adventitia layer.
2Object-affected harmful factors
If conservative ablation is performed to avoid renal artery stenosis, then artery safety is improved, but denervation efficacy is reduced
Solution Approach 1:
The microwave ablation system creates a depth-dependent temperature distribution with higher temperatures at greater depths where the nerves are located and lower temperatures at the luminal surface. This allows aggressive ablation of nerves without causing stenosis, overcoming the limitation of conservative ablation.
Solution Approach 2:
The system changes the thermal parameters by using microwave energy with specific penetration characteristics and controlling the temperature gradient through irrigation cooling. This enables the ablation zone to extend deeper into the artery wall while keeping the luminal surface temperature safe, thereby improving denervation efficacy without causing stenosis.
3Reliability
If full thickness ablation is performed to ensure complete nerve destruction, then denervation efficacy is improved, but renal artery stenosis occurs
Solution Approach 1:
The microwave radiation produces a characteristic heating pattern with maximum temperature at intermediate depths and lower temperature at the surface. By positioning the radiator appropriately and using irrigation cooling, complete nerve destruction in the adventitia layer is achieved while the luminal surface remains protected from thermal injury.
Solution Approach 2:
The irrigation fluid serves as a protective intermediary layer that absorbs thermal energy before it reaches the luminal surface. This allows the application of sufficient microwave power to ensure complete nerve destruction while preventing full-thickness thermal injury that would cause stenosis.
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 denervates renal nerves with minimal injury to the renal artery, providing a more efficient and safer procedure for hypertension treatment by achieving targeted thermal ablation with reduced risk of renal artery stenosis.
Implementation Method 1
a microwave ablation device comprising a feed line, a microwave radiator and a device outer sheath
Implementation Method 2
the conductive core forming a radiating element electrically insulated from its surrounding environment
Implementation Method 3
the sheath in use allowing an irrigation liquid to flow therethrough
Data Source
AI summary
A microwave ablation device (10) comprises a feed line (22), a microwave radiator and a device outer sheath (46) in which at least part of the feed line (22) is contained. The sheath (46) in use, allows an irrigation liquid to flow therethrough, wherein the feed line has a junction (38) with the radiator (22) has an outer conducting shield (28) terminating and insulated at the junction (38). The feed line (22) has a conductive core (32) that extends to the radiator (24). The conductive core forms a radiating element (34) electrically insulated from its surrounding environment. The radiator (24) is unbalanced.