Catheter Variable Arcuate Distal Section for Pulmonary Vein Isolation
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Solution Overview
Problem
Existing catheters for ablating and mapping pulmonary vein ostia face challenges in accommodating varying anatomy, achieving complete tissue contact, and ensuring accurate visualization due to fixed curved or circular end sections that may not fit all ostia sizes and angles, leading to incomplete contact and potential inefficiencies in ablation procedures.
Innovation Solution
A catheter with a distal assembly featuring a contraction wire-actuated, shape-memory support member that allows the curved or circular electrode-bearing portion to be variably configured, either on-axis or off-axis, and irrigated ablation ring electrodes with apertures for improved flow distribution, enabling better load distribution and tissue contact verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed curved or circular end section is used, then the catheter structure is simple, but the adaptability to different ostia sizes and angles is poor
Solution Approach 1:
The catheter employs a shape memory alloy support member that can dynamically change the configuration of the distal assembly between straight and curved states. This dynamic capability allows the catheter to adapt to different ostia geometries and approach angles, resolving the contradiction between adaptability and structural simplicity by introducing controlled complexity only when needed.
Solution Approach 2:
The shape memory alloy support member enables parameter changes in the distal assembly configuration through temperature or mechanical activation. By changing the curvature radius and orientation of the distal assembly, the catheter can accommodate varying ostia sizes and angles while maintaining a relatively simple overall structure that only becomes complex during active adaptation.
2Reliability
If a fixed configuration catheter is used, then the device is easy to operate, but complete tissue contact cannot be achieved for all anatomies
Solution Approach 1:
The dynamic reconfiguration capability allows the operator to adjust the distal assembly shape to match the specific anatomy being treated. This ensures reliable complete tissue contact by adapting the catheter shape to the patient's unique anatomy, while the shape memory alloy provides this adaptability through a relatively simple actuation mechanism that does not significantly complicate operation.
Solution Approach 2:
The shape memory alloy support member can be pre-configured to specific curvature patterns before use. This preliminary action allows the catheter to be deployed in an optimized configuration for the specific anatomical target, ensuring complete tissue contact from the outset without requiring complex real-time adjustments during the procedure.
3Object-affected harmful factors
If irrigation flow is not optimized, then the device structure is simple, but charring occurs during ablation
Solution Approach 1:
The ablation electrode incorporates apertures that enable optimized irrigation flow distribution across the electrode surface. This porous structure allows cooling fluid to reach the tissue-electrode interface effectively, preventing charring during ablation. The aperture design adds minimal structural complexity while significantly improving the harmful factor control.
4Productivity
If the distal assembly cannot be reconfigured, then the procedure time is short, but the ablation efficiency is reduced due to incomplete tissue contact
Solution Approach 1:
The shape memory alloy support member enables rapid reconfiguration of the distal assembly shape during the procedure. This dynamic capability allows the operator to optimize tissue contact for different anatomical targets without requiring complete catheter withdrawal and repositioning, thereby improving ablation efficiency while minimizing additional procedure time.
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 catheter achieves more consistent and complete tissue contact, enhanced mapping and ablation efficiency, and reduced risk of charring through adjustable configuration and improved irrigation, facilitating precise pulmonary vein isolation and ablation.
Implementation Method 1
a shape-memory support member that transforms from a generally straight configuration to a generally curved configuration
Implementation Method 2
a contraction wire that pulls the distal assembly to contract the curved configuration
Implementation Method 3
RF energy is then applied through an electrode on the catheter in order to create a lesion
Implementation Method 4
The ablation electrode is irrigated through apertures in the ablation electrode
Data Source
Figure 1~18
Figure 2
Figure 3
AI summary
A catheter includes an elongated body, a distal assembly with a shape-memory member defining a generally circular form, and a control handle adapted to actuate a deflection puller wire for deflecting a portion of the elongated body, and a contraction wire for contracting the generally circular form. The generally circular form which carries at least one ring electrode has an off-edge configuration relative to the elongated body such that a longitudinal axis of the elongated body does not intersect the circumference of the circular form and the generally circular form spirals about the longitudinal axis of the elongated body. Moreover, the circular form can have an on-axis configuration such that the longitudinal axis of the elongated body is axially aligned with a central longitudinal axis of the circular form, or an off-axis configuration such that these axes are axially offset from each other. In a more detailed embodiment, the catheter has a distal assembly with a helical form or a crescent form carrying a plurality of irrigated ablation ring electrodes and a plurality of smaller ring electrodes adapted for impedance recording or PV potential recording. A support member with shape memory extends through the distal assembly to provide the helical or crescent form. The support member has a varying stiffness along its length, for example, a decreasing stiffness toward a distal end of the support member. The support member can also be hollow so that it can receive a mandrel whose stiffness is greater than that of the support member.