Catheter Flow Sensor Transit Time Control
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Solution Overview
Problem
Existing cardiac tissue ablation techniques using radiofrequency energy face challenges in controlling local heating, leading to either ineffective lesions or excessive tissue damage due to overheating, which complicates the treatment of arrhythmias.
Innovation Solution
A method and apparatus that involve delivering heat energy to irrigation fluid within a catheter, measuring the transit time of the heated fluid using thermocouples, and adjusting the fluid flow to maintain a desired transit time, thereby controlling the cooling and ablation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radiofrequency energy is applied to create a large lesion for effective ablation, then the effectiveness of treating arrhythmia is improved, but excessive local heating occurs causing tissue charring and high impedance
Solution Approach 1:
The patent applies preliminary cooling action by delivering chilled irrigation fluid to the tissue surface before and during radiofrequency energy application. This pre-cooling prevents excessive temperature rise and tissue charring, allowing effective ablation without harmful overheating effects
Solution Approach 2:
The patent introduces chilled irrigation fluid as an intermediary substance between the radiofrequency electrode and the tissue. This fluid mediator absorbs excess heat and protects the tissue from direct thermal damage while allowing the ablation energy to effectively treat the arrhythmia
2Object-affected harmful factors
If slower heating is used to provide better control of ablation, then excessive local heating is reduced, but the procedure time is unduly prolonged
Solution Approach 1:
The patent maintains continuous delivery of chilled irrigation fluid throughout the ablation procedure, ensuring uninterrupted cooling action. This continuous cooling allows faster heating rates to be used without risk of overheating, reducing procedure time while maintaining safety
Solution Approach 2:
The patent employs temperature sensing that provides feedback on tissue temperature during ablation. This feedback mechanism allows real-time adjustment of heating and cooling rates, enabling faster overall treatment while preventing excessive heating through dynamic control
3Object-affected harmful factors
If thermocouples are integrated within the electrode for feedback control, then control of local heating is improved, but device complexity increases
Solution Approach 1:
The patent uses chilled irrigation fluid as an external cooling mediator rather than integrating thermocouples within the electrode. This approach provides effective temperature control through the cooling fluid system, avoiding the complexity of embedded temperature sensors while maintaining good thermal management
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 control of tissue heating, reducing the risk of excessive heating and improving the effectiveness of cardiac tissue ablation by optimizing fluid flow and cooling, thus enhancing the procedure's efficiency and safety.
Implementation Method 1
a heating element, disposed in a non-contacting relationship with the irrigation fluid flowing in the lumen
Implementation Method 2
a thermocouple disposed downstream from the heating element in a direction of flow of the irrigation fluid for measuring a temperature of the irrigation fluid
Implementation Method 3
irrigation of the target tissue during the energy application, using chilled fluids
Data Source
AI summary
Methods and systems facilitate catheterization of a living subject by passing a fluid through an irrigation conduit. Heat energy is delivered to the conduit to create a heated pod of irrigation fluid that propagates downstream from the heat source. A departure time of the pod from a first location in the conduit is recorded, and an arrival time of the pod is detected at a second location that is downstream from the first location. A transit time of the pod from the first location to the second location is determined, and the flow of the fluid is adjusted responsively to the transit time.