Impedance-Based Tissue Contact Detection for Ablation Catheters
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Solution Overview
Problem
Minimally-invasive cardiac ablation procedures face challenges in accurately positioning medical devices within the heart due to the tortuous and moving cardiac environment, risking damage to surrounding tissues during treatments like pulmonary vein ablation.
Innovation Solution
A medical system that uses impedance measurements to determine the position of electrodes relative to pulmonary veins, preventing ablative energy delivery to undesirably placed electrodes and conducting non-ablative RF energy for continuous or duty-cycled impedance monitoring between electrodes and a ground electrode, allowing for accurate placement and real-time alerts on electrode positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external imaging systems are used to locate targeted tissue, then some positioning information is provided, but accurate positioning remains difficult due to the tortuous and moving cardiac environment
Solution Approach 1:
The patent replaces mechanical/external imaging positioning systems with an electrical field-based impedance sensing system. The ablation catheter uses electrical impedance measurements through its electrodes to detect tissue contact and differentiate between pulmonary vein tissue and surrounding structures, substituting complex imaging mechanics with simpler electrical field interactions.
Solution Approach 2:
The patent introduces electrical impedance as an intermediary parameter to indirectly detect electrode-tissue contact and tissue type. Instead of directly visualizing the catheter position with imaging systems, the system uses impedance measurements as a mediator to infer positioning accuracy and tissue contact status.
2Reliability
If ablative energy is delivered to treat arrhythmias, then treatment efficacy is achieved, but risk of damage to surrounding healthy tissue increases
Solution Approach 1:
The patent implements real-time feedback through impedance monitoring during ablation. The system continuously measures impedance changes at the electrode-tissue interface and uses this feedback to detect when the electrode is in contact with pulmonary vein tissue versus surrounding structures, allowing dynamic adjustment or termination of energy delivery to prevent damage to healthy tissue.
Solution Approach 2:
The patent applies preliminary anti-action by using impedance sensing to identify and protect vulnerable structures before ablative energy is delivered. The system pre-detects the presence of pulmonary vein tissue or other critical structures adjacent to the electrode, and prevents or modifies energy delivery in advance to avoid harmful effects on surrounding healthy tissue.
3Measurement precision
If impedance measurements are continuously monitored, then electrode positioning accuracy is improved, but energy consumption and system complexity increase
Solution Approach 1:
The patent employs periodic action by implementing impedance measurements at specific intervals and during critical phases of the ablation procedure, rather than continuous monitoring. The system measures impedance before energy delivery, during duty cycles, and when tissue contact status may have changed, optimizing the balance between positioning precision and energy consumption.
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 positioning of electrodes within the heart, reducing the risk of damaging surrounding tissues by preventing ablative energy delivery to the pulmonary veins and ensuring effective contact with targeted tissue during procedures.
Implementation Method 1
measuring an impedance value between the at least one electrode and the tissue
Implementation Method 2
delivering radiofrequency energy to the at least one electrode, wherein the delivered radiofrequency energy is sufficient to ablate at least a portion of the tissue region
Data Source
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AI summary
Systems and methods for assessing tissue contact, including positioning an electrode adjacent a tissue region; delivering radiofrequency energy to the electrode, wherein the delivered radiofrequency energy is sufficient to ablate at least a portion of the tissue region; obtaining a plurality of impedance measurements from the electrode during the delivery of the radiofrequency energy; calculating a change in the impedance measurements over a pre-determined time period; and generating an alert if the calculated change is less than a pre-defined value.