LVAD Physiological Control Using Ventricular Volume Feedback
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Solution Overview
Problem
Current LVADs operate at a fixed pump speed, failing to adapt to dynamic heart failure conditions, leading to insufficient cardiac output during exercise, ventricular suction events, and adverse events like endothelial dysfunction and gastrointestinal bleeding, due to lack of sensitivity to hemodynamic parameters and reliance on impractical or unreliable sensors.
Innovation Solution
A physiological control system using resonantly coupled sensors to measure ventricular chamber volume, implementing a gain-scheduling proportional-integral control algorithm to adjust pump speed based on end-diastolic volume, preventing ventricular suction and enhancing vascular pulsatility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed pump speed is used, then device complexity is reduced, but adaptability to physiological demands deteriorates
Solution Approach 1:
The control system continuously monitors hemodynamic parameters (ventricular pressure, flow rate, heart rate) and uses this feedback to dynamically adjust pump speed. The controller compares measured parameters with target values and modifies pump operation in real-time to maintain optimal hemodynamics across varying physiological conditions.
Solution Approach 2:
The system transitions from static fixed-speed operation to dynamic variable-speed control. The pump speed is continuously adjusted based on real-time hemodynamic conditions, allowing the device to adapt to changing physiological demands during rest, exercise, and transitional states.
2Manufacturing precision
If fixed pump speed is used, then manufacturing precision requirements are reduced, but measurement precision of hemodynamic parameters deteriorates
Solution Approach 1:
The system replaces complex mechanical sensing mechanisms with advanced signal processing and computational methods. Hemodynamic parameters are derived from motor current analysis, acoustic sensing, and pressure waveform analysis, eliminating the need for direct implantable flow and pressure sensors.
Solution Approach 2:
The control system uses intermediary measurements (motor current, acoustic signals, pressure waveforms) to indirectly infer hemodynamic parameters. These intermediary signals serve as proxies for direct measurement, allowing accurate assessment of ventricular pressure and flow without invasive sensors.
3Adaptability or versatility
If sensor-based control is implemented, then adaptability to physiological demands is improved, but device complexity increases
Solution Approach 1:
The system extracts control information from existing pump components and external monitoring devices rather than adding dedicated sensors. Motor current data, acoustic signals, and pressure waveforms from the pump system itself are utilized as control inputs, eliminating the need for separate implantable flow and pressure sensors.
Solution Approach 2:
The control system uses multi-functional signals that serve multiple purposes. Motor current data is used for both pump control and hemodynamic parameter estimation, acoustic sensors serve both diagnostic and control functions, and the system can operate with different sensor configurations depending on patient needs.
4Use of energy by moving object
If fixed pump speed is used, then power consumption is reduced, but productivity in meeting cardiac demand deteriorates
Solution Approach 1:
The pump operates with dynamic speed adjustment rather than fixed speed. During rest, the pump operates at lower speeds to conserve energy, while during exercise or increased metabolic demand, the pump automatically increases speed to maintain adequate cardiac output and tissue perfusion.
Solution Approach 2:
The system changes operational parameters (pump speed, flow rate) based on physiological state. By adjusting these parameters dynamically, the system optimizes the balance between power consumption and productivity, ensuring adequate cardiac output during high-demand states while minimizing energy use during rest.
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 effectively regulates pump speed to meet physiological demands, preventing ventricular suction and improving cardiac output, reducing adverse events, and enabling long-term reliability without the need for implantable sensors.
Implementation Method 1
measured chamber volume is based on a signal generated from resonantly coupled sensors
Data Source
AI summary
A physiological control system for a blood pump includes a controller configured to receive an input signal indicative of ventricular chamber volume, and generate an output pump control signal based on the input signal. A physiological method for controlling a blood pump is also disclosed.