Implantable Cardiac Support Flow Measurement With Dual Pressure Sensors
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Solution Overview
Problem
Existing methods for determining cardiac output in implanted left ventricular assist devices (LVADs) are error-prone and limited to cardiac surgery due to reliance on statistical assumptions and transcutaneous catheters, making accurate measurement of pump volume flow (Qp) challenging, especially at high support levels where aortic valve flow (Qa) becomes negligible.
Innovation Solution
An implantable vascular support system equipped with two pressure sensors, preferably MEMS sensors, is used to measure static and total pressures at different points in the fluid channel to calculate pump volume flow (Qp) using Bernoulli's equation, enabling continuous and accurate measurement outside surgical settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dilution methods with transcutaneous catheters are used to determine cardiac output, then measurement can be performed during cardiac surgery, but the method cannot provide continuous measurement outside surgical settings
Solution Approach 1:
The patent extracts the measurement function from external catheters and transcutaneous devices, integrating pressure sensors directly into the implantable support system itself. This allows the system to measure pump volume flow continuously without requiring external catheter insertion, resolving the contradiction between measurement precision and adaptability by making the measurement capability inherent to the implanted device.
Solution Approach 2:
The implantable support system performs self-measurement of pump volume flow using integrated pressure sensors, eliminating the need for external catheters and transcutaneous access. The system serves its own measurement needs, enabling continuous monitoring both during and after surgery, thus achieving both precision and continuous availability.
2Device complexity
If statistical assumptions and pump characteristic maps are used to correlate pump volume flow, then measurement can be performed with existing components, but the measurement becomes error-prone
Solution Approach 1:
The patent replaces statistical correlation methods and pump characteristic maps with direct physical measurement using pressure sensors. Instead of inferring pump volume flow from electrical power consumption and statistical assumptions, the system directly measures pressure differentials and calculates flow using Bernoulli's equation, eliminating the errors inherent in statistical methods while maintaining reasonable system complexity.
Solution Approach 2:
The patent introduces pressure sensors as intermediary measurement elements that directly capture the physical state (pressure) needed to calculate pump volume flow. These sensors serve as mediators between the fluid dynamics and the measurement system, providing accurate direct measurement data rather than requiring statistical inference from other parameters.
3Measurement precision
If ultrasonic sensor systems are used for flow measurement, then accurate measurement can be achieved, but the system requires large space and has high cost
Solution Approach 1:
The patent employs small, inexpensive pressure sensors (such as MEMS sensors) that can be integrated directly into the support system, replacing expensive and space-consuming ultrasonic sensor systems. These compact pressure sensors provide sufficient measurement precision for pump volume flow while occupying minimal space and reducing overall system cost.
Solution Approach 2:
The patent uses pressure measurement as a simplified copy or alternative approach to direct flow measurement. Instead of measuring flow velocity directly with complex ultrasonic systems, the system measures pressure (a related physical quantity) and calculates flow from it, achieving accurate measurement with much smaller and cheaper sensors.
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 system provides a continuous, energy-efficient, and accurate measurement of Qp, comparable to thermodilution catheters, without the need for external catheters, using pressure sensors that are small in size and require minimal space, offering improved measurement quality.
Implementation Method 1
calculate pump volume flow (Qp) using Bernoulli's equation, enabling continuous and accurate measurement outside surgical settings
Data Source
AI summary
A cardiac support system may include a tubular structure configured to permit fluid to flow therethrough. The cardiac support system may include a first pressure sensor connected to the tubular structure and configured to determine at least one of a static pressure or a total pressure in a first region of the cardiac support system having a first cross-sectional area. The cardiac support system may include a second pressure sensor connected to the tubular structure and configured to determine at least one of a static pressure or a total pressure in a second region of the cardiac support system having a second cross-sectional area of a different size relative to the first cross-sectional area.