Cannula Apparatus for VADs with Segmented Flow and Priming
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Solution Overview
Problem
The insertion of Ventricular Assist Devices (VADs) is complicated by the need for muscle coring and the risk of stroke due to ventricular intracavity free air and air introduction during pump priming, which can lead to suction occlusion and micro air bubbles.
Innovation Solution
A cannula apparatus with an outer and inner cannula that can be configured between open and closed arrangements to prevent tissue occlusion and air entry, featuring multiple sidewall openings to ensure blood flow and a priming mechanism that maintains fluid within the cannula without offloading the ventricle, reducing the risk of air introduction during placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct ventricular coring is performed to place the distal tip of the cannula, then the distal tip is free from adjacent trabeculated fibro-muscular attachments, but the procedure becomes more complex and carries higher risk of complications
Solution Approach 1:
The cannula is divided into multiple segments with multiple drainage holes distributed along its length rather than a single distal tip hole. This segmentation allows blood to enter through multiple locations, eliminating the need to precisely position a single distal tip away from trabeculated structures, thereby simplifying the surgical procedure while maintaining reliable cannula function
Solution Approach 2:
A retrieval snare is introduced as an intermediary tool to capture and remove the cannula if proper placement cannot be achieved or if complications arise. This intermediary device provides a safety mechanism that reduces surgical risk and simplifies the overall procedure by offering a non-invasive retrieval option rather than requiring complex removal maneuvers
2Object-affected harmful factors
If surgical maneuvers such as hypodermic needles are used to evacuate air from the outflow graft, then air is removed from the system, but additional bleeding risks are introduced and procedure time is prolonged
Solution Approach 1:
The cannula and VAD are primed with blood or blood-compatible fluid before implantation, and air evacuation ports are pre-positioned in the outflow graft. This preliminary preparation allows air to be evacuated through the pre-designed ports during normal surgical flow rather than requiring additional time-consuming maneuvers with hypodermic needles after implantation
Solution Approach 2:
Designated air evacuation ports serve as intermediary structures that provide a controlled pathway for air removal. These ports allow air to escape without requiring direct needle puncture of the graft, thereby eliminating the need for additional bleeding control measures and reducing procedure time
3Object-affected harmful factors
If hypodermic needles are used to puncture outflow graft material for air evacuation, then air is removed from the system, but post-implant bleeding risks are introduced
Solution Approach 1:
The outflow graft incorporates designated air evacuation ports as intermediary structures that provide a controlled pathway for air removal. These ports are integrated into the graft material itself, allowing air to escape without requiring external needle puncture that would create uncontrolled bleeding risks. The ports can be accessed and sealed in a controlled manner, eliminating the need for additional bleeding control measures
4Object-affected harmful factors
If suction lines are used to evacuate air from the device chamber, then air is removed from the system, but micro air bubbles are introduced into the outflow graft
Solution Approach 1:
The cannula incorporates a distal air evacuation port as an intermediary structure that provides a dedicated pathway for air removal from the device chamber. This port is positioned and designed to allow air to escape directly from the chamber without creating negative pressure that would draw blood and micro air bubbles into the outflow graft. The port serves as a controlled air evacuation route that prevents the harmful side effect of bubble introduction
Data Source
AI summary
Cannula apparatus, ventricular assist systems including the cannula apparatus, and methods of priming and placing the cannula apparatus and ventricular assist systems are described herein.