Microwave Electrosurgical Snare for Low-Voltage Tissue Coagulation
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Solution Overview
Problem
Existing surgical snares for polyp removal in the GI tract require high electrical power for RF cutting, which increases the risk of thermal damage to the bowel wall due to high peak voltages associated with monopolar and bipolar coagulation.
Innovation Solution
A surgical snare that radiates microwave frequency energy, with a retractable loop and a radiating structure acting as a microwave monopole antenna, reducing collateral thermal damage by confining heat to the target tissue with lower peak voltages (10 V or less) and effectively coagulating blood.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high electrical power is used for RF cutting, then cutting effectiveness is improved, but thermal damage to surrounding tissue increases
Solution Approach 1:
The patent changes the frequency parameter of electromagnetic energy from traditional RF (lower frequency) to microwave frequency (higher frequency, at least three orders of magnitude higher). This parameter change enables more effective cutting and coagulation at lower power levels, thereby reducing thermal damage to surrounding tissue while maintaining cutting effectiveness
Solution Approach 2:
The patent employs pulsed microwave energy delivery rather than continuous RF energy. By delivering energy in controlled pulses, the system achieves effective tissue cutting and coagulation while allowing thermal diffusion between pulses, preventing excessive heat accumulation and collateral thermal damage to the bowel wall
2Power
If monopolar or bipolar coagulation is used, then cutting action is achieved, but peak voltage becomes excessively high (exceeding 450V)
Solution Approach 1:
The patent transitions from monopolar/bipolar RF systems operating at high voltages (>450V peak) to a microwave system operating at low voltages (10V or less peak). This fundamental parameter change in operating voltage and frequency enables the system to achieve effective tissue cutting and coagulation without the excessively high peak voltages associated with traditional RF coagulation methods
3Reliability
If RF energy is used for tissue coagulation, then coagulation is achieved, but collateral thermal damage occurs
Solution Approach 1:
The patent employs microwave frequency energy (at least three orders of magnitude higher than typical RF) to achieve tissue coagulation. This frequency parameter change enables more precise energy deposition and better control of thermal spread, providing effective coagulation while minimizing collateral thermal damage to surrounding healthy tissue
Solution Approach 2:
The patent replaces the traditional RF electrical field mechanism with a microwave electromagnetic field mechanism. This substitution changes the fundamental physics of energy interaction with tissue, allowing for more confined and controllable thermal effects that achieve reliable coagulation without extensive collateral thermal damage
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 energy reduces the risk of thermal damage to surrounding tissue, providing effective coagulation and facilitating the removal of polyps while minimizing collateral damage.
Implementation Method 1
a radiating structure arranged to radiate microwave frequency energy into the area encircled by the retractable loop
Implementation Method 2
microwave frequency energy (e.g. electromagnetic energy with a frequency of at least three orders of magnitude higher than typical RF energy) within the area encircled by the snare's loop
Implementation Method 3
a coaxial cable for conveying microwave frequency energy to the radiating structure, the coaxial cable comprising an inner conductor, an outer conductor surrounding and coaxial with the inner conductor, and a dielectric material separating the inner conductor and the outer conductor
Implementation Method 4
the emitted microwave field can be more effective than an RF field at coagulating blood
Implementation Method 5
By controlling the shape of the emitted microwave field, the risk of collateral thermal damage can be reduced
Data Source
AI summary
An electrosurgical snare, e.g. suitably sized for insertion down the instrument channel of an endoscope, arranged to radiate microwave frequency energy (e.g. having a frequency greater than 1 GHz) from an elongate conductive element within an area encircled by a retractable loop. The elongate conductive element and retractable loop may be independently slidable relative to a snare base at a distal end of a sleeve to provide an appropriate device configuration. By controlling the shape of the emitted microwave field, the risk of collateral thermal damage can be reduced.