Ablation Device Flow Impedance Choked Flow
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Solution Overview
Problem
Conventional ablation systems face challenges in reliably suppressing blood flow into the catheter during a leak, which can lead to hemorrhagic shock and damage to the ablation system.
Innovation Solution
An ablation device with a flow impedance between the boiling chamber and the ablation medium drain line, utilizing the choked flow effect to maintain pressure balance, and a closure mechanism with valves to enclose a predefined volume, preventing blood from entering the system in case of a leak.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vacuum source is connected to the return line to actively exhaust the refrigerant, then the refrigerant can be efficiently removed from the catheter, but blood may be sucked into the catheter causing hemorrhagic shock
Solution Approach 1:
A flow impedance element is pre-installed in the return line between the boiling chamber and the vacuum source connection point. This element is positioned beforehand to limit the maximum flow velocity of any fluid (including blood) that might be suctioned into the catheter during vacuum operation, thereby preventing hemorrhagic shock before it can occur
Solution Approach 2:
The flow impedance element acts as an intermediary component between the vacuum source and the boiling chamber. It mediates the suction force by restricting the flow velocity, allowing refrigerant exhaustion while blocking the harmful effect of high-velocity blood suction into the catheter
2Stress or pressure
If the flow velocity of ablation medium in the flow impedance is increased to at least 50% of acoustic velocity, then the pressure balance is maintained and refrigerant flow is controlled, but the system complexity increases due to precise flow control requirements
Solution Approach 1:
The flow impedance element is designed with specific geometric parameters (cross-sectional area, length, shape) that naturally restrict the flow velocity of the ablation medium to at least 50% of acoustic velocity. By changing the physical parameters of the flow path rather than adding complex active control systems, the pressure balance in the boiling chamber is maintained while avoiding increased system complexity
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
The solution effectively prevents blood from entering the ablation device during a leak, reducing the risk of hemorrhagic shock and minimizing damage to the system, while ensuring efficient operation and safety.
Implementation Method 1
the ablation medium has an average flow velocity in the flow impedance of at least about 50% of the acoustic velocity
Implementation Method 2
an ablation medium conveying unit adapted for conveying the ablation medium to the boiling chamber, through the flow impedance and to the ablation medium drain line
Implementation Method 3
a boiling chamber adapted for boiling an ablation medium for ablating material from an object
Data Source
Figure 1
Figure 1a
Figure 2
AI summary
An ablation device (1), comprises a boiling chamber (42) adapted for boiling an ablation medium for ablating material from an object; an ablation medium drain line (46, 32) adapted for draining the ablation medium received from the boiling chamber (42); a flow impedance (44) arranged between the boiling chamber (42) and the ablation medium drain line (46, 32); an ablation medium conveying unit (62) adapted for conveying the ablation medium to the boiling chamber (42), through the flow impedance (44) and to the ablation medium drain line (46, 32); wherein the ablation medium conveying unit (62) and the flow impedance (44) are adapted so that the ablation medium has an average flow velocity in the flow impedance (44) of at least 50% of the acoustic velocity.