Expandable Sheath Trapping Dilator Mechanism

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Solution Overview

Problem

Existing introducer sheaths for intracardiac heart pump assemblies face challenges such as premature tearing, excessive force requirements for removal, and complications in vessel closure due to their non-radial expandability and potential for clot formation.

Innovation Solution

An expandable introducer sheath with a dilator configured to trap the distal tip of the sheath, allowing for tensioning to reduce the outer diameter and achieve a lower profile during insertion, thereby minimizing patient complications and facilitating easier device positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a peel-away introducer sheath is used, then the sheath can be easily removed after device insertion, but the sheath may tear too easily or require excessive force to remove

Engineering Contradiction:

Improveease of sheath removalVSAvoidsheath structural integrity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The introducer sheath transitions from a non-expandable static structure to a radially expandable dynamic structure. The sheath can expand radially to accommodate the device and then be collapsed for removal, providing controlled mechanical behavior that prevents premature tearing while enabling easy removal through radial collapse rather than longitudinal tearing.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The sheath's radial dimension is changed dynamically through expansion and collapse. By changing the radial parameter of the sheath, the device can be accommodated during insertion, and then the sheath is collapsed radially to facilitate removal without requiring forceful tearing, thus maintaining structural integrity while enabling easy removal.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If a non-expandable sheath is used, then the sheath structure is simpler, but the outer diameter must be large enough to accommodate the largest device portion

Engineering Contradiction:

Improvesheath structure simplicityVSAvoidsheath outer diameter

Core Design Contradiction:

Device complexityVSVolume of moving object

Solution Approach 1:

The sheath transitions from a static fixed-diameter structure to a dynamic radially expandable structure. This allows the sheath to have a smaller collapsed diameter for insertion, then expand radially to accommodate the device, and finally collapse again for removal. This dynamic behavior eliminates the need for a constantly large outer diameter while maintaining the ability to accommodate large devices.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The device is nested within the expandable sheath during the insertion phase. The sheath encapsulates the device, allowing the combined assembly to pass through the vasculature. Once positioned, the device is deployed and the sheath is collapsed and removed, leaving the device in place. This nesting approach allows temporary accommodation of large devices without requiring a permanently large sheath.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Volume of moving object

If an expandable sheath is used, then the sheath can accommodate larger devices, but the sheath may be completely flexible leading to kinking or buckling

Engineering Contradiction:

Improvesheath inner diameterVSAvoidsheath rigidity

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

The sheath structure incorporates different mechanical properties in different locations or aspects. The radial expandability provides flexibility and collapse capability, while the axial rigidity is maintained through structural design elements that prevent kinking and buckling during insertion and device passage. This local differentiation of mechanical properties allows the sheath to simultaneously accommodate large devices and maintain structural integrity.

Inventive Principle:

Principle #3Local quality

4Ease of operation

If a peel-away sheath is used, then the sheath can be removed after device passage, but the arteriotomy may be stretched requiring larger vessel opening

Engineering Contradiction:

Improvesheath removabilityVSAvoidvessel opening size

Core Design Contradiction:

Ease of operationVSLength of stationary object

Solution Approach 1:

The sheath employs radial expansion and collapse rather than longitudinal tearing for removal. The sheath is collapsed radially to a small profile and then pulled back through the arteriotomy, minimizing stretching of the vessel opening. This dynamic radial collapse mechanism allows sheath removal without permanently enlarging the access site, facilitating easier closure compared to peel-away techniques that require longitudinal tearing and can stretch the arteriotomy.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20250121161A1Expandable sheath with trapping dilator

Publication Date: 2025.04.17 ABIOMED INC

AI summary

An expandable introducer sheath with a dilator configured to trap the distal tip of the introducer sheath. In some examples, the dilator may have a tip configured to slide relative to the body of the dilator, such that moving the dilator body in the proximal direction relative to the dilator tip reveals an area in which the outer diameter of the dilator transitions to an area of reduced diameter, and moving the dilator body in the distal direction relative to the dilator tip may enable the distal tip of the introducer sheath to become trapped.