Infra-Renal Vena Cava Occlusion With Feedback-Controlled Preload Relief
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Solution Overview
Problem
Cardiac dysfunction and kidney dysfunction often form a vicious cycle, leading to worsening congestive heart failure and renal issues due to increased renal venous pressure, which affects renal perfusion and function, particularly in heart failure patients.
Innovation Solution
A blood pump with a support cage is placed in the renal vein or vena cava to maintain alignment and separation from the vessel wall, using a radial extension to anchor the pump and reduce venous pressure, combined with an occlusion element to partially occlude the vena cava, controlled by a system that adjusts operation based on physiological parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a blood pump is placed in the vena cava to reduce renal venous pressure, then renal perfusion improves, but the device complexity increases
Solution Approach 1:
The blood pump device is divided into distinct functional modules: an occlusion element (balloon or stent) for blocking venous flow, a pump element (impeller or diaphragm) for generating pressure gradient, and a delivery system. This segmentation allows each component to perform its specific function efficiently while simplifying the overall device design and manufacturing.
Solution Approach 2:
The pump element is nested within the occlusion element structure, with the impeller or diaphragm positioned inside the occlusion balloon or stent framework. This nested configuration reduces the number of separate components, simplifies deployment, and minimizes the device profile during catheter delivery while maintaining full functionality during operation.
2Stress or pressure
If an occlusion element is used to partially occlude the vena cava, then cardiac preload reduces, but the risk of harmful factors increases
Solution Approach 1:
The occlusion element is designed to provide partial occlusion of the vena cava rather than complete blockage, creating a controlled pressure gradient that redirects blood flow through the pump element. This partial action achieves the therapeutic effect of reducing cardiac preload while avoiding the harmful consequences of complete occlusion, such as severe venous congestion or organ ischemia.
Solution Approach 2:
The device incorporates pressure sensors that monitor venous pressure upstream and downstream of the occlusion element, providing real-time feedback to a control system. This feedback mechanism allows automatic adjustment of the occlusion degree and pump operation to maintain safe pressure levels, preventing harmful effects while optimizing the therapeutic benefit of reduced cardiac preload.
3Stress or pressure
If the pump operates continuously to maintain pressure gradient, then renal venous pressure lowers, but energy consumption increases
Solution Approach 1:
The pump element operates in periodic cycles rather than continuously, with the diaphragm or impeller activating intermittently to maintain the pressure gradient. This periodic operation reduces energy consumption while still achieving the therapeutic effect of lowering renal venous pressure, as the pressure gradient is maintained between pump cycles through the elastic properties of the vascular system and the occlusion element.
Solution Approach 2:
The device utilizes the body's own physiological mechanisms to maintain pressure gradient between pump cycles, leveraging vascular elasticity and the occlusion element's structural properties. This self-service approach minimizes the energy required from the pump motor, as the system automatically sustains the pressure differential without continuous active pumping, thereby reducing overall energy consumption while maintaining therapeutic effect.
Data Source
AI summary
Apparatus and methods are described including reducing cardiac preload of a subject by partially occluding a vena cava of the subject at an infra-renal location. One or more physiological parameters of the subject are monitored, the one or more physiological parameters including lower body venous pressure, central venous pressure, central venous blood flow, renal venous pressure, cardiac diameter, cardiac volume, arterial pressure, and/or arterial blood flow. An extent to which the vena cava is occluded at the infra-renal location is modulated, responsively to the one or more physiological parameters. Other applications are also described.