On-Axis Position Sensor in Irrigated Ablation Tip
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Solution Overview
Problem
Conventional electrophysiologic catheters face challenges in effective cooling and position sensing during ablation procedures, leading to increased impedance, coagulum formation, and reduced accuracy due to the external placement of position sensors and limited space for irrigation fluid flow.
Innovation Solution
A catheter design with an on-axis, distally located electromagnetic position sensor within the irrigated ablation tip electrode, featuring a shell with fluid ports and a baffle configuration to promote uniform fluid flow and dispersion, reducing temperature variations and enhancing thermal transfer while protecting the sensor from RF ablation and bending stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the position sensor is placed externally on the catheter, then the sensor can detect position, but the sensor accuracy is reduced due to distance from the tip electrode and the sensor is exposed to bending stresses
Solution Approach 1:
The position sensor is nested inside the tip electrode housing, placing it in a protected internal environment that shields it from bending stresses while maintaining its proximity to the active tip for accurate position sensing during ablation procedures
Solution Approach 2:
The tip electrode housing acts as an intermediary structure that houses and protects the position sensor, providing a stable mounting environment that isolates the sensor from mechanical stresses while allowing it to accurately track the catheter tip position
2Temperature
If multiple coolant channels are added to reduce hot spots, then temperature uniformity improves, but the device complexity and fluid management burden increase
Solution Approach 1:
The single coolant channel is segmented into multiple flow paths by internal baffles and flow directors, creating distributed cooling zones that eliminate hot spots while maintaining a simple single-channel external structure for easy fluid management
Solution Approach 2:
Internal baffles and flow director structures act as intermediaries within the coolant channel, distributing the cooling fluid across multiple zones to achieve uniform temperature control without requiring multiple external channels or complex fluid management systems
3Temperature
If the irrigation flow rate is increased to improve cooling, then temperature control improves, but the fluid load on the patient increases
Solution Approach 1:
The cooling system delivers irrigation fluid precisely where needed at the tip electrode surface through strategically positioned outlets, creating localized high-velocity cooling jets that maximize cooling efficiency with minimal total fluid volume
Solution Approach 2:
The system changes the flow parameters by using high-velocity, low-volume irrigation through the tip electrode, transforming the cooling approach from high-flow bulk cooling to targeted jet cooling that achieves superior temperature control with reduced fluid load
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 design improves cooling efficiency, reduces fluid load on the patient, and maintains accurate position sensing, enabling larger and more uniform lesions with lower fluid flow rates, thus enhancing the effectiveness and safety of the ablation procedure.
Implementation Method 1
A position sensor, such as an electromagnetic (EM) sensor, is located in a distal and on-axis position in an irrigated ablation tip electrode
Implementation Method 2
Another method is to irrigate the ablation electrode, e.g., with physiologic saline at room temperature, to actively cool the ablation electrode
Implementation Method 3
The tip electrode has an internal configuration that promotes fluid diffusion and dispersion
Data Source
AI summary
A catheter carries a position sensor in a distal, on-axis position in an irrigated ablation tip electrode. The tip electrode has a shell wall that defines a cavity through which fluid flows and exits via fluid ports formed in the shell wall. The cavity is sealed by an internal member extends into the cavity with a baffle portion and a distal portion. The distal portion safely houses the position sensor and the baffle portion diffuses and disperses fluid entering the tip electrode for a more uniform flow through the cavity. The distal portion is configured to provide an annular region that runs along the length of the tip electrode to better feed fluid to the more distal fluid ports on the tip electrode for more uniform cooling at all locations on the tip electrode.