Self-Expanding Venous Cannula Stenting for CPB Drainage
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Solution Overview
Problem
Inadequate venous drainage during cardiopulmonary bypass (CPB) due to the collapse of venous system segments, leading to reduced pump flow and perfusion, particularly with traditional short cannulas and negative pressure application, which complicates surgical procedures and can result in major volume loss.
Innovation Solution
The use of longer self-expanding venous cannulas with an open wall design that temporarily stents the caval axis, allowing blood to enter the cannula lumen at any level and preventing collapse, thereby enhancing drainage and supporting the venous system during CPB.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional short cannulas are used with negative pressure application, then the venous system can be drained, but the venous system segments collapse leading to inadequate drainage
Solution Approach 1:
The patent employs a flexible mesh structure within the cannula that acts as a stent to prevent collapse of the venous system segments. This mesh structure maintains the luminal width and prevents wall collapse while allowing the cannula to remain flexible for insertion and adaptation to the vessel geometry.
Solution Approach 2:
The cannula is designed with multiple segments or zones along its length, with the distal portion having a different configuration than the proximal portion. The mesh structure is distributed along specific segments of the cannula to provide targeted support where needed while maintaining overall flexibility and drainage function.
2Productivity
If longer cannulas are used to drain the entire venous system, then drainage coverage is improved, but the cannula becomes more complex and harder to manage
Solution Approach 1:
The long cannula is designed with segmented zones having different properties - the proximal portion has a first configuration optimized for insertion and the distal portion has a second configuration optimized for stenting and drainage. This segmentation allows each portion to be optimized for its specific function while maintaining overall manageability.
Solution Approach 2:
The cannula incorporates dynamic elements including a collapsible mesh structure that can be compressed during insertion and then expands to provide stenting support. The ability to change configuration from a compressed state during insertion to an expanded state during operation reduces the effective length and complexity during manipulation while providing full-length drainage coverage when deployed.
3Productivity
If self-expanding cannulas are used to maintain luminal width, then venous drainage is enhanced, but the cannula requires more complex expansion mechanisms
Solution Approach 1:
The cannula employs a self-expanding mesh structure that automatically expands to its full diameter when inserted into the venous system, eliminating the need for external balloons or扩张 devices. The mesh structure inherently provides the expansion force through its elastic properties and geometric configuration, allowing the cannula to self-adjust to the vessel lumen.
Solution Approach 2:
The mesh structure utilizes material properties and geometric parameters that enable automatic expansion. The mesh configuration, material elasticity, and structural design are optimized to provide self-expanding characteristics, where the cannula transitions from a compressed insertion state to an expanded drainage state through passive elastic recovery and geometric expansion forces.
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
This approach significantly increases venous drainage flow by up to 51% compared to standard cannulas, achieving better perfusion and simplifying surgical procedures by maintaining the luminal width and preventing venous wall collapse, even at low drainage pressures without augmentation.
Implementation Method 1
The cannula comprises a mesh structure which is expandable from a compressed insertion state to a full drainage state
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A self expanding cannula (6) with improved drainage properties based upon its greater length is provided, along with methods of using the cannula in cardiopulmonary bypass.