Expandable Catheter with Resistive Sensing for Lumen Size Normalization
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Solution Overview
Problem
Current methods for treating body lumens, such as the esophagus, face challenges in accurately measuring the size of the lumen for precise ablational therapy, leading to potential over- or under-treatment due to variations in lumen size and leaks in the system, which can result in inaccurate diameter estimates.
Innovation Solution
The development of methods and systems that use expandable operative elements with sensing circuitry, such as resistivity or inductance-based circuits, to measure the size of body lumens, allowing for controlled delivery of ablative energy by expanding the element to a predetermined pressure and varying the sensing circuitry accordingly, enabling precise energy normalization to the tissue surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If expandable catheters are used to treat body lumens, then treatment efficiency is improved when the catheter is at or slightly larger than the diameter of the esophageal wall, but accurate measurement of lumen size is difficult to achieve
Solution Approach 1:
The patent replaces mechanical measurement systems (expandable catheters requiring manual sizing) with an electrical measurement system. The sensing circuitry uses electrical resistivity changes to directly measure lumen diameter, providing accurate measurements without complex mechanical instrumentation. This electrical approach substitutes for traditional mechanical sizing methods and enables precise energy delivery control.
Solution Approach 2:
The expandable catheter integrates multiple functions: it serves as both the treatment delivery mechanism and the measurement device. The sensing circuitry is incorporated into the catheter structure itself, allowing simultaneous measurement of lumen size and delivery of ablational energy through the same device, eliminating the need for separate measurement and treatment instruments.
2Manufacturing precision
If pressure is applied to expand the catheter to achieve therapeutic contact, then treatment uniformity is improved, but accurate diameter estimation becomes difficult due to leaks in the system
Solution Approach 1:
The patent replaces mechanical pressure-based sizing methods with an electrical sensing system. Instead of relying on pressure measurements that are affected by leaks, the system uses electrical resistivity sensing to directly measure lumen diameter. This substitution eliminates the measurement errors caused by system leaks while maintaining the pressure expansion method for achieving uniform therapeutic contact.
3Ease of operation
If the catheter profile is made as small as possible for ease of delivery, then ease of delivery is improved, but treatment effectiveness is reduced when the catheter is too small relative to the esophageal wall diameter
Solution Approach 1:
The catheter is designed with dynamic expandability, transitioning from a compact delivery profile to an expanded treatment profile. The catheter is delivered in a collapsed state for easy insertion, then expanded within the lumen to achieve therapeutic contact. This dynamic transformation allows the device to optimize both ease of delivery and treatment effectiveness at different stages of the procedure.
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
This approach allows for high-resolution, real-time measurement of lumen size, ensuring uniform and controlled depth of treatment, reducing the risk of complications like perforation or incomplete treatment by normalizing energy delivery based on accurate size measurements.
Implementation Method 1
an expandable operative element having sensing circuitry with a resistivity that varies according to a size of the operative element
Implementation Method 2
an expandable operative element having sensing circuitry with an inductance that varies according to a size of the operative element
Implementation Method 3
expanding the operative element to a predetermined pressure
Implementation Method 4
an ablational energy delivery element to ablate a target tissue in a body lumen
Data Source
AI summary
Methods and devices for measuring the size of a body lumen and a method for ablating tissue that uses the measurement to normalize delivery of ablational energy from an expandable operative element to a luminal target of varying circumference are provided. The method includes inserting into the lumen an expandable operative element having circuitry with resistivity or inductance that varies with circumference of the operative element, varying the expansion of the operative element with an expansion medium, measuring the resistivity of the circuitry, and relating the resistivity or inductance to a value for the circumference of the operative element. In some embodiments the sizing circuit includes a conductive elastomer wrapped around the operative element. Other embodiments apply to operative elements that include an overlapping energy delivery element support in which the overlap varies inversely with respect to the state of expansion, and electrodes that sense the amount of the overlap.