Pulsed RF Ablation Electrode Temperature Control
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Solution Overview
Problem
Current radiofrequency ablation systems are limited by the risk of steam pops when using high continuous power levels, restricting the ability to achieve desired lesion sizes efficiently.
Innovation Solution
Selecting specific ranges for RF power (70 W-100 W), contact force (5 g-50 g), temperature (55° C.-65° C.), and irrigation rate (8-45 ml/min) to perform ablation, with real-time monitoring of impedance and temperature to adjust power delivery and prevent adverse effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous power levels of 20-50 watts are used for RF ablation, then the ablation process is safe without steam pops, but the ablation time is extended to approximately 1 minute
Solution Approach 1:
The patent applies periodic action by delivering RF energy in pulsed cycles rather than continuous operation. The system delivers high power RF energy for a first time period, then delivers no RF energy for a second time period, repeating this cycle throughout the ablation procedure. This allows higher peak power delivery while preventing continuous heating that causes steam pops, thereby reducing overall ablation time while maintaining safety.
Solution Approach 2:
The patent implements dynamics by making the RF power delivery variable and adaptive rather than static. The system dynamically adjusts power delivery based on real-time temperature monitoring and impedance changes, switching between high power and zero power states. This dynamic control allows the system to operate at higher power levels safely by adapting the delivery pattern to prevent steam pop formation.
2Productivity
If high power levels are used to reduce ablation time, then the ablation process becomes faster, but steam pops are formed causing safety risks
Solution Approach 1:
The system uses periodic action to deliver high power RF energy in controlled pulses followed by rest periods. During the first time period, high power is delivered to achieve rapid tissue heating and缩短 ablation time. During the second time period, no power is delivered to allow heat dissipation and prevent steam pop formation. This cyclic pattern enables high productivity while eliminating the harmful steam pop effect.
Solution Approach 2:
The system applies preliminary anti-action by proactively interrupting high power delivery before steam pops can form. The periodic off-cycles serve as preventive measures that counteract the tendency toward steam pop formation that would otherwise occur during continuous high power delivery. This preemptive approach allows aggressive power settings that would normally cause harm to be used safely.
3Loss of time
If RF energy is delivered in pulsed cycles with high power for short durations, then ablation time is reduced and safety is improved, but the system complexity increases due to real-time monitoring requirements
Solution Approach 1:
The system implements feedback by continuously monitoring temperature and impedance during RF energy delivery and using this information to control the pulsed power delivery. Temperature sensors provide real-time feedback on tissue heating, and impedance changes indicate tissue properties and potential steam pop risks. This feedback loop enables the system to automatically adjust the pulsed delivery pattern, achieving safe and efficient ablation without requiring complex external control systems.
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 the safe application of higher RF power to reduce ablation time without steam pops, allowing for precise control of lesion depth and size.
Implementation Method 1
Tissue surrounding the electrode in the target region is destroyed by heating via RF electric current
Implementation Method 2
RF ablation is typically performed at continuous power levels of the order of 20-50 watts, with a contact force of approximately 10 g, and under irrigation
Data Source
AI summary
A method, including selecting a first maximum radiofrequency (RF) power to be delivered by an electrode within a range of 70 W-100 W, and selecting a second maximum RF power to be delivered by the electrode within a range of 20 W-60 W. The method also includes selecting an allowable force on the electrode within a range of 5 g-50 g, selecting a maximum allowable temperature, of tissue to be ablated, within a range of 55° C.-65° C., and selecting an irrigation rate for providing irrigation fluid to the electrode within a range of 8-45 ml/min. The method further includes performing an ablation of tissue using the selected values by initially using the first power, switching to the second power after a predefined time between 3 s and 6 s, and terminating the ablation after a total time for the ablation between 10 s and 20 s.