Cryoablation Dose Control via Time to Effect Mapping

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Solution Overview

Problem

Current cryoablation methods face challenges in accurately directing and controlling the depth of tissue cooling, leading to potential collateral damage and inadequate treatment due to imprecise monitoring of lesion formation and tissue temperature during procedures for cardiac arrhythmias.

Innovation Solution

A system and method that utilize a processor to calculate the time to effect (TTE) and time to isolation (TTI) based on mapping signals, determining a recommended cryoablation dose to achieve electrical isolation, incorporating a sensing device and treatment device with a temperature-adjusting capability to optimize cryotreatment delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If real-time temperature monitoring is implemented to control cryoablation depth, then treatment precision is improved, but device complexity and procedural difficulty increase

Engineering Contradiction:

Improvecryoablation depth controlVSAvoidtemperature monitoring system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/thermal monitoring system with an electrical field-based system. Mapping electrodes detect electrical signals from cardiac tissue to indirectly measure tissue thickness and cryoablation depth, eliminating the need for direct temperature sensors and complex thermal monitoring infrastructure

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces electrical mapping signals as an intermediary measurement method. Instead of directly measuring temperature or physical depth, the system uses electrical signal characteristics (amplitude, morphology) from mapping electrodes positioned near the target tissue to infer tissue properties and cryoablation effectiveness

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If extended cryoablation time is applied to ensure adequate treatment depth, then treatment effectiveness is improved, but risk of collateral damage to non-target tissue increases

Engineering Contradiction:

Improveelectrical isolation achievementVSAvoidcollateral tissue damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where mapping electrodes continuously monitor electrical signals during cryoablation. The system detects changes in signal amplitude and morphology that indicate approaching critical tissue depths, providing real-time feedback to adjust or terminate cryoablation before collateral damage occurs

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent performs preliminary electrical mapping to assess tissue thickness and electrical characteristics before initiating cryoablation. This preliminary assessment allows the system to pre-determine safe treatment parameters and duration specific to each patient's anatomy, preventing both under-treatment and over-treatment

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If traditional fixed-duration cryoablation protocols are used, then procedural simplicity is maintained, but treatment precision and adaptability to individual tissue characteristics decrease

Engineering Contradiction:

Improveprocedure simplicityVSAvoidtreatment customization to tissue thickness

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent transforms fixed, static cryoablation protocols into dynamic, adaptive protocols. The system continuously adjusts treatment parameters based on real-time electrical mapping data, allowing the cryoablation duration and intensity to vary according to each patient's specific tissue characteristics while maintaining procedural flow

Inventive Principle:

Principle #15Dynamics

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 precise determination of the optimum cryoablation dose, reducing collateral damage and ensuring effective electrical isolation by correlating TTE and TTI with tissue thickness, enabling more accurate and controlled treatment without the need for real-time temperature monitoring.

Implementation Method 1

During cryoablation, tissue is cooled by a cryotreatment catheter until the aberrant electrical conduction is eliminated

Methodology Applied

Scientific EffectCryogenic cooling: Cryogenics

Implementation Method 2

the pulmonary vein ostium and/or antrum may be cooled until the pulmonary vein(s) is/are isolated from the left atrium

Methodology Applied

Scientific EffectFreezing: Freezing

Data Source

PatentUS11172974B2Method of using time to effect (TTE) to estimate the optimum cryodose to apply to a pulmonary vein

Publication Date: 2021.11.16 MEDTRONIC CRYOCATH LP

AI summary

A system and method for determining the optimum dose of cryotreatment to an area of target tissue to achieve isolation based on the time to effect (TTE). The system may generally include a treatment device, a sensing device, and a processor programmed to calculate the optimum dose of cryotreatment, in seconds, based on TTE. The TTE may be based on electrical signals received by the processor from the sensing device. The processor may be further programmed to automatically terminate a cryoablation procedure when the optimum dose of cryotreatment has elapsed. The optimum dose of cryotreatment may be the time, in seconds, it takes to achieve isolation, which may be the time it takes for an area of tissue to reach approximately −20° C.