Spring-Loaded Actuator for Controlled Sheath Retraction
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Solution Overview
Problem
Current endovascular introducer systems require manual force to retract the outer sheath, leading to potential loss of control and incorrect deployment of medical devices due to jolting, especially in larger systems or those following tortuous paths within the patient.
Innovation Solution
A deployment assembly with a sprung-loaded actuator element providing rotational restoring force, coupled with a speed control device for controlled retraction, minimizing jolting and allowing for automated retraction without manual effort, thus maintaining precise control during device deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual force is applied to retract the outer sheath, then the sheath can be withdrawn to expose the device, but the introducer may jolt and move unintentionally out of position
Solution Approach 1:
The deployment assembly employs a spring-loaded actuator that automatically provides the retraction force needed to withdraw the outer sheath. The spring mechanism self-generates the necessary force through its restoring force, eliminating the need for the physician to manually pull the sheath while maintaining stable introducer positioning.
Solution Approach 2:
The patent replaces the manual mechanical pulling action with an automated spring-loaded mechanical system. The spring-loaded actuator converts elastic potential energy stored in the spring into kinetic energy for sheath retraction, substituting the physician's manual force application with a controlled mechanical system that prevents introducer jolting.
2Force
If substantial force is applied to retract the outer sheath in larger introducer systems, then the sheath can be withdrawn, but the risk of introducer movement increases significantly
Solution Approach 1:
The spring-loaded actuator replaces manual force application with a controlled mechanical system. The spring provides substantial retraction force automatically, eliminating the need for the physician to apply large manual forces that could cause introducer movement and deployment location inaccuracies.
Solution Approach 2:
The spring-loaded actuator serves as an intermediary mechanism between the sheath retraction requirement and the introducer positioning stability. It mediates the force application by providing controlled, automated retraction force that achieves sheath withdrawal without the destabilizing effect of manual pulling on the introducer.
3Ease of operation
If a two-handed operation is used to retract the sheath, then the sheath can be withdrawn, but the physician risks losing control of the deployment process
Solution Approach 1:
The spring-loaded actuator performs the sheath retraction function automatically without requiring the physician's direct manual intervention. The physician simply activates the mechanism, and the spring-loaded system self-executes the retraction process, maintaining deployment control while simplifying operation.
Solution Approach 2:
The patent substitutes the two-handed manual operation with an automated spring-loaded mechanical system. This replacement eliminates the control risks associated with manual two-handed manipulation while maintaining ease of operation through simple activation of the automated mechanism.
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 ensures smooth and precise retraction of the outer sheath, reducing the risk of device misplacement and allowing for efficient deployment of medical devices, even in complex anatomical paths, by eliminating the need for manual force and minimizing longitudinal movement of the introducer.
Implementation Method 1
The free end of the draw cable is attached to a body member (20) and to a spiral spring (90). The spiral spring (90) is constrained within a recess (92) formed in the casing (32).
Implementation Method 2
A compression spring which is oriented at an angle to the retraction direction, for example at 30°, 45° and even up to 90°.
Implementation Method 3
The damper (61) provides a frictional force to the toothed wheel (50) which is controllable by the trigger (16) so as to control a speed of the toothed wheel (50).
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A deployment assembly (10) for an introducer used for introducing into a patient a stent or other device, the deployment assembly including a housing 30 carrying a sprung loaded (90) actuator (44,50). The actuator includes a toothed wheel (50) carrying a spool (48) around which a retraction strap (44) can be wound. The strap (44) is coupled to a body member (26) of the introducer and through this to the outer sheath (14) thereof. A trigger (16) is provided for operating the actuator (44, 50). When the trigger (16) is pressed, the actuator winds, under the force produced by the spring (90), the strap (44) to thereby retract the outer sheath (14) so as to expose and then deploy the device carried on the introducer. The mechanism is such that a surgeon need not expend his own energy to retract the outer sheath (14) since this force is provided by the spring (90). Furthermore, the spring (90) acts in a plane other than that of the direction of retraction of the sheath (14), which minimises the risk of inadvertent movement of the introducer as the sheath (14) is being retracted.