Implantable Blood Pump Preload Tracking Using Pump Filling Index
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Solution Overview
Problem
Current implantable blood pumps lack an efficient method to track cardiac preload, leading to potential ventricle overfilling or underfilling, which can cause systemic congestion or edema in patients with failing hearts.
Innovation Solution
A method to estimate cardiac preload by calculating a beat-to-beat pump filling index (PFI) from the current waveform of the implanted blood pump, using thresholds to generate alerts and adjust the impeller speed accordingly to maintain optimal cardiac function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a predetermined set speed is maintained to prevent ventricle overfilling or underfilling, then ventricular function is protected, but preload tracking capability is insufficient leading to potential congestion or edema
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring the current waveform from the blood pump and calculating the pump filling index (PFI) in real-time. The PFI is derived from waveform characteristics including amplitude (difference between peak and trough) and timing parameters (duration of filling phase). This feedback loop enables the system to detect preload changes and generate alerts when PFI deviates from predetermined thresholds, allowing clinicians to adjust pump settings to prevent ventricular overfilling or underfilling while maintaining reliable ventricular function protection.
2Productivity
If VAD assists the failing ventricle to migrate blood into circulation, then appropriate perfusion is achieved, but efficient preload tracking method is lacking
Solution Approach 1:
The patent replaces complex mechanical or invasive measurement systems with an electrical measurement approach. Instead of using pressure sensors, volume sensors, or other complex mechanical devices to track preload, the system utilizes the existing current waveform from the blood pump's motor. By analyzing waveform characteristics (amplitude, duration, shape) that naturally vary with preload conditions, the system derives the pump filling index without adding mechanical complexity. This substitution maintains high blood perfusion efficiency while avoiding device complexity increases.
3Measurement precision
If beat-to-beat PFI calculation is implemented from current waveform, then real-time preload monitoring is achieved, but computational complexity increases
Solution Approach 1:
The patent segments the current waveform into distinct phases for analysis: the filling phase (from trough to peak) and the ejection phase. By identifying key waveform features such as the trough point, peak point, and inflection points, the system divides the continuous waveform into manageable segments. The pump filling index is then calculated using simple ratios of amplitude differences and time durations of these segmented phases. This segmentation approach enables beat-to-beat preload monitoring with high measurement precision while keeping computational complexity low through straightforward arithmetic operations on segmented waveform data.
Data Source
AI summary
A method of estimating a patient's cardiac preload in a patient having an implantable blood pump. The method includes generating a current waveform from operation of the implanted blood pump. A beat-to-beat pump filling index (PFI) is calculated, the PFI is calculated by dividing a current amplitude component by a time component, the amplitude component being calculated by subtracting a trough of the current waveform from an inflection point divided by an amplitude difference of peak to trough of the waveform, the time component being calculated by dividing a time between the trough and the inflection point by a time between the peak and the trough. An alert is generated if the PFI deviates from predetermined thresholds.