Insulated Cutting Cables for Minimally Invasive Tissue Excision
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Solution Overview
Problem
Existing minimally invasive breast biopsy methods, such as electrosurgical cutting, face challenges including thermal damage to surrounding tissue, nerve stimulation, and inadequate cutting in varying tissue densities, leading to inefficiencies and patient discomfort.
Innovation Solution
A tubular delivery cannula with flexible leaf members and polymeric extrusion members, featuring insulated cutting and pursing cables, ensures minimal invasive tissue excision by controlling electrical current flow to prevent overheating and thermal damage, while accommodating varying tissue resistivities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electrosurgical cutting is used for minimally invasive breast biopsy, then tissue excision can be achieved through small incisions, but thermal damage occurs to surrounding tissue
Solution Approach 1:
The cutting cable is divided into multiple independently controllable segments or zones along its length. Each segment can be activated selectively to cut different portions of tissue, allowing precise control of the cutting path and limiting thermal exposure to only the immediate cutting zone rather than the entire cable length.
Solution Approach 2:
The electrosurgical cutting employs pulsed or intermittent electrical current delivery rather than continuous application. By delivering energy in controlled pulses with duty cycles optimized for tissue cutting, the system achieves effective incision while allowing thermal dissipation between pulses, preventing excessive heat accumulation in surrounding tissues.
2Ease of operation
If electrosurgical cutting is used for tissue excision, then cutting can be performed through insulated cables, but nerve stimulation occurs causing patient discomfort
Solution Approach 1:
The electrical current is delivered in pulsed fashion with carefully controlled duration and frequency. By limiting the duty cycle and pulse width, the system prevents sustained electrical stimulation of nerves while maintaining effective cutting during the active pulse periods. The intermittent nature of pulsed delivery allows neural tissue to recover between stimuli, preventing discomfort.
Solution Approach 2:
The electrical parameters including voltage, current amplitude, pulse duration, and frequency are optimized to distinguish between cutting and nerve stimulation thresholds. By operating at parameter combinations that exceed the dielectric breakdown threshold for cutting but remain below sustained nerve stimulation thresholds, the system achieves cutting efficacy while minimizing patient discomfort.
3Productivity
If electrosurgical cutting is used for tissue excision, then cutting capability is achieved, but inadequate cutting occurs in varying tissue densities
Solution Approach 1:
The system dynamically adjusts electrical parameters such as power output, pulse duration, and frequency based on real-time feedback from tissue impedance sensing. When encountering denser or more resistant tissue, the system automatically increases power delivery within safety limits to maintain cutting effectiveness, while adapting to softer tissues to prevent excessive energy application.
Solution Approach 2:
The electrosurgical system incorporates impedance sensing that continuously monitors tissue electrical properties during cutting. This feedback information is used to adjust cutting parameters in real-time, compensating for variations in tissue density, composition, and hydration. The closed-loop control ensures consistent cutting performance across heterogeneous breast tissue types.
4Measurement precision
If larger tissue volumes are excised for biopsy, then diagnostic accuracy improves, but cosmetic appearance and patient trauma worsen
Solution Approach 1:
The electrosurgical cutting system enables precise localization of the cutting path to exactly match the boundaries of the lesion identified by imaging guidance. By confining thermal and mechanical damage to the immediate surgical margin rather than requiring large excision zones, the system achieves adequate diagnostic sampling while preserving cosmetic appearance and reducing patient trauma.
Solution Approach 2:
The system replaces traditional mechanical cutting with electrosurgical cutting through insulated cables. This substitution allows cutting to occur at a distance from the incision site, enabling the incision to be made in optimal cosmetic locations while the actual tissue excision occurs deeper within the breast tissue guided by imaging, thus separating cosmetic considerations from diagnostic 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
Enables precise and efficient excision of defined tissue volumes with reduced thermal and electrical harm to surrounding tissue, improving procedural safety and efficacy.
Implementation Method 1
a resistively heated cutting and pursing cable extending along the distal tip of the leaf member and multi-lumen polymeric extrusion assembly which (a) provides a thermal cutting effect by virtue of being resistively heated and maintained above a temperature threshold
Data Source
AI summary
The recovery of an intact volume of tissue proceeds with a delivery cannula distal end positioned in confronting adjacency with the volume of tissue to be recovered. A tissue cutting and capture assembly formed of a plurality of metal leafs is deployed from the distal end of the delivery cannula. The tips of these leafs carry a pursing cable assembly, which is electrically excited to electrosurgically cut around and circumscribe the tissue volume. These pursing cables are tensioned to complete the envelopment of the tissue volumes by drawing the leaf tips together. An essential attribute of the disclosed apparatus is the confinement of the path of electrical conduction of constant current required to achieve tissue cutting to only those portions of the deploying and retracting resistively heated portion of the cutting and pursing cable that are in direct contact with tissue.