Outflow Cannula Geometry for Blood Pump Backflow Occlusion
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Solution Overview
Problem
Existing blood pumps face challenges in preventing backflow and causing minimal harm to the vessel while maintaining effective blood flow, particularly due to the limited size of the central lumen and short contact time of drug delivery devices.
Innovation Solution
The blood pump design incorporates an outflow cannula with an enlarged intermediate portion that contacts the vessel wall to occlude it, reducing backflow and minimizing vessel harm, and includes a drug eluting device for prolonged contact with the vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circumferential balloon is used to occlude the vessel, then backflow is prevented, but the central lumen size is limited and blood flow is restricted
Solution Approach 1:
The outflow cannula is divided into three distinct portions: a first portion for blood intake, a second enlarged intermediate portion for vessel occlusion, and a third portion for blood output. This segmentation allows each portion to perform its specific function optimally without compromising the others, resolving the contradiction between occlusion effectiveness and blood flow delivery.
Solution Approach 2:
The invention transitions from a two-dimensional circumferential balloon occlusion to a three-dimensional outflow cannula structure with an enlarged intermediate portion. This dimensional change allows the cannula to occupy the same radial space for occlusion while maintaining a sufficient central lumen for blood flow through its extended longitudinal structure.
2Reliability
If the outflow cannula is made larger to prevent backflow, then vessel occlusion is improved, but the risk of vessel harm increases
Solution Approach 1:
The outflow cannula features a localized enlarged intermediate portion that contacts the vessel wall for occlusion, while the upstream and downstream portions maintain smaller diameters for blood flow. This local quality variation allows effective occlusion at the intermediate portion without requiring the entire cannula to be large, thereby reducing overall vessel harm risk.
Solution Approach 2:
The enlarged intermediate portion of the outflow cannula acts as an intermediary structure between the pump and the vessel wall. It distributes the occlusion force over a larger area compared to a traditional balloon, reducing pressure concentration and minimizing direct harm to the vessel while still achieving effective occlusion.
3Device complexity
If a drug eluting device is used with short contact time, then device complexity is reduced, but drug delivery effectiveness is limited
Solution Approach 1:
The outflow cannula serves multiple functions simultaneously: it acts as a structural support for the pump, provides vessel occlusion through its enlarged intermediate portion, and serves as a drug delivery conduit. This multi-functionality allows the device to maintain prolonged contact with the vessel for drug delivery without adding separate complex components.
Solution Approach 2:
The invention merges the drug eluting function with the outflow cannula structure. The drug eluting portion is integrated into the outflow cannula, combining the structural and drug delivery functions into a single component, thereby extending drug delivery time without significantly increasing device complexity.
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 design effectively prevents backflow and reduces vessel damage by distributing contact force over a larger area, while allowing for prolonged drug delivery to the vessel.
Implementation Method 1
the outflow cannula is sized and shaped to contact an inner wall of the vessel in which the blood pump is placed during operation of the blood pump, in order to occlude the vessel during operation of the blood pump
Implementation Method 2
an impeller is rotatably supported within the pump casing, with the impeller being provided with blades for conveying blood
Implementation Method 3
blood is conveyed from the blood flow outlet of the pump casing into and through the intermediate portion of the outflow cannula towards the downstream end portion of the outflow cannula
Implementation Method 4
The design effectively prevents backflow and reduces vessel damage by distributing contact force over a larger area
Data Source
AI summary
A blood pump comprises a pump casing having a blood flow inlet and a blood flow outlet, and an impeller arranged in said pump casing so as to be rotatable about an axis of rotation. The impeller has blades sized and shaped for conveying blood from the blood flow inlet to the blood flow outlet. The blood pump also has an outflow cannula having an upstream end portion, a downstream end portion and an intermediate portion extending between the upstream end portion and the downstream end portion. The upstream end portion of the outflow cannula is connected to the pump casing such that blood is conveyed from the blood flow outlet of the pump casing into and through the intermediate portion of the outflow cannula towards the downstream end portion of the outflow cannula, wherein the downstream end portion has a blood flow outlet through which blood can exit the outflow cannula. At least a portion of the intermediate portion of the outflow cannula has an outer diameter that is larger than an outer diameter of the pump casing.