Ventricular Assist Pump Cannula Clamping and Airflow Equalization
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Solution Overview
Problem
Existing ventricular assist devices (VADs) face issues with cannula connection stability, difficulty in installing cannula holders, inconsistent air distribution, and potential damage to the pump housing due to excessive fastening force, as well as challenges in removing air bubbles before implantation.
Innovation Solution
The VAD design includes a cannula holder with clasps to secure cannulas, a torqueable wrench to prevent over-torqueing, an airflow channel for homogeneous pressure distribution, and a purge device to remove air bubbles, enhancing stability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fastener is used to connect the cannula to the pump housing to prevent air leakage, then sealing reliability is improved, but the pump housing may be damaged due to excessive fastening force
Solution Approach 1:
A compliant sealing element (e.g., O-ring, gasket) is placed between the fastener and the pump housing to absorb and distribute the fastening force. This cushioning element prevents excessive point loads that could damage the pump housing while maintaining adequate sealing pressure to prevent air leakage.
Solution Approach 2:
The sealing interface is designed with localized compliance through materials or structures (such as elastomeric seals or distributed fastening points) that allow the sealing surface to deform locally to accommodate manufacturing tolerances and distribute forces evenly, preventing both leakage and housing damage.
2Reliability
If the VAD uses a closed design to prevent contamination, then sterilization and safety are improved, but cannula holders cannot be installed after cannula connection
Solution Approach 1:
The VAD system is divided into modular components: the pump housing (closed design for sterilization), the cannula connector, and the cannula holder. The holder is designed as a separate accessory that attaches to the connector interface, allowing the main housing to remain sealed while enabling post-assembly holder installation through the designed interface.
Solution Approach 2:
A connector interface acts as an intermediary between the closed pump housing and the external cannula holder. This interface allows the holder to be attached after cannula connection while maintaining the sterile barrier of the closed housing design, as the interface is designed to preserve sterility during the attachment process.
3Power
If air is pumped into the VAD to pressurize the sac, then pump function is activated, but air is not consistently and homogeneously distributed to the sac
Solution Approach 1:
A dedicated air introduction port and distribution channel are extracted from the main pump chamber. This separate air delivery system allows controlled introduction of air through specific pathways that ensure homogeneous distribution throughout the sac, preventing localized over-pressurization or trapped air pockets.
Solution Approach 2:
The air distribution system utilizes pneumatic principles with multiple distribution ports, capillary channels, or pressure-equalizing features that leverage fluid dynamics to automatically balance air pressure throughout the sac volume, ensuring homogeneous distribution without manual intervention.
4Volume of moving object
If the VAD is designed with a compact structure to reduce implantation size, then device size is reduced, but it becomes difficult to remove air bubbles from the sac before implantation
Solution Approach 1:
Air bubble removal features (such as purge ports, elevation channels, or one-way valves) are pre-integrated into the compact VAD design. These features allow air bubbles to be actively removed through controlled pathways during the priming process before implantation, eliminating the need for larger external removal equipment while maintaining compact dimensions.
Solution Approach 2:
The air bubble removal mechanism utilizes vertical or gravitational dimensionality within the compact structure. By designing air vents or purge channels that leverage gravity and orientation, small air bubbles can be efficiently removed through the compact structure without requiring excessive space, as the removal path exploits the third dimension rather than requiring lateral expansion.
Data Source
AI summary
Embodiments include Ventricular Assist Devices (VADs) with clips that help hold a cannula to the VAD. In some embodiments the clip embraces a cannula that has been placed around a cannula connector. In further embodiments an additional clip connects the first clip to the VAD housing preventing the first clip from slipping. The clip and additional clip may form a single piece. Further embodiments include a blood pumping sac located inside a cavity in the VAD forming one or more air chambers between the sac and the cavity walls, and an airflow channel leading from the air chambers to an airflow port allowing the sac to be evenly pressurized and depressurized.