Cryoablation Mapping Electrodes for PV Occlusion and Lesion Sensing
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Solution Overview
Problem
Current methods for assessing tissue contact and lesion formation during cardiac ablation procedures, such as pulmonary vein isolation, are inadequate, leading to incomplete lesions and potential recurrence of arrhythmias due to suboptimal cryoballoon occlusion and temperature application, and rely on inconclusive impedance measurements and auxiliary imaging systems.
Innovation Solution
A medical system with a treatment element and mapping elements, including temperature sensors and impedance electrodes, that determine transmurality of lesions by comparing impedance and temperature measurements before and after cryogenic fluid circulation, allowing for real-time evaluation of ice formation and occlusion without the need for renal toxic dyes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fluoroscopic imaging with radiopaque contrast medium is used to assess PV occlusion, then occlusion assessment can be performed, but the patient is exposed to large doses of contrast medium and radiation
Solution Approach 1:
The patent replaces fluoroscopic imaging (optical/mechanical system) with electrical impedance sensing to assess PV occlusion. Multiple electrodes measure impedance changes in the pulmonary vein, providing real-time occlusion assessment without radiation or contrast medium exposure. The impedance variations directly reflect blood flow status and occlusion quality.
Solution Approach 2:
The patent uses electrical impedance as an intermediary parameter to indirectly assess PV occlusion status. Instead of directly imaging the occlusion, the system measures impedance changes caused by occlusion-induced alterations in blood flow and tissue electrical properties, providing a safe indirect measurement method.
2Measurement precision
If impedance measurements are used to monitor tissue contact, then contact status can be assessed, but the results are inconclusive and sensors are not located on the entire treatment element
Solution Approach 1:
The patent divides the treatment element into multiple segments, each equipped with its own impedance sensing electrodes. This segmentation allows independent measurement of tissue contact at different locations along the treatment element, providing comprehensive and location-specific contact status information rather than a single aggregate measurement.
Solution Approach 2:
The treatment element is designed with multifunctional capabilities: it can deliver cryoablation therapy while simultaneously performing tissue contact assessment through integrated impedance electrodes. This multi-functionality eliminates the need for separate monitoring devices and ensures comprehensive contact evaluation across the entire treatment surface.
3Measurement precision
If pressure monitoring through guidewire lumen is used to assess occlusion, then occlusion status can be determined, but the exact location of inadequate tissue contact cannot be pinpointed in real time
Solution Approach 1:
The patent segments the monitoring function by placing multiple impedance electrodes at different locations along the treatment element. Each electrode independently measures impedance at its specific location, enabling real-time identification of which particular segment has inadequate tissue contact, thus pinpointing the exact location of contact problems.
Solution Approach 2:
The system provides real-time feedback through continuous impedance measurements from multiple electrode locations. This feedback allows immediate detection and localization of inadequate tissue contact, enabling the operator to adjust the treatment element position or pressure at the specific problematic location rather than guessing based on general pressure readings.
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 determination of lesion quality and completeness, ensuring effective tissue ablation and occlusion, reducing the risk of arrhythmia recurrence and minimizing exposure to contrast medium and radiation.
Implementation Method 1
circulation of the cryogenic fluid within the treatment element causing formation of an ice ball between the treatment element and the area of tissue
Implementation Method 2
a plurality of mapping elements on the treatment element... processing circuitry being configured to determine transmurality of a lesion based on signals received from the plurality of mapping elements
Data Source
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AI summary
A device, system, and method for treating an area of tissue and evaluating lesion formation and quality. The system may include a medical device having a plurality of mapping electrodes on a treatment element, the plurality of mapping electrodes being configured to record from the area of tissue at least one of unipolar impedance measurements, bipolar impedance measurements, local electrical activity, and pace threshold measurements before, during, and after circulation of the cryogenic fluid within the treatment element. These measurements may be transmitted to a control unit having processing circuitry configured to compare pre-treatment measurements, in-treatment measurements, and/or post-treatment measurements to each other and/or to threshold values to determine occlusion and/or lesion quality, such as lesion transmurality.