VAD Motor Current Waveform Analysis for Heart Rate
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for monitoring heart rate in patients with implantable blood pumps rely on electrocardiogram (ECG) signals, which require electrodes and are not feasible without them, necessitating an alternative method for heart rate determination using VAD circuitry.
Innovation Solution
A method and system that measure and analyze the motor current signal of an implantable blood pump to detect events indicative of cardiac cycles, using a combination of unfiltered and filtered signals to determine heart rate, allowing for heart rate calculation based on elapsed time between specific events in the current signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ECG signals are used to detect heart rate, then heart rate monitoring accuracy is improved, but device complexity increases due to requirement of ECG electrodes
Solution Approach 1:
The patent extracts the heart rate detection function from the ECG electrode system and relocates it to the VAD motor control circuitry. By analyzing the motor current signal already present in the VAD system, the invention eliminates the need for separate ECG electrodes while maintaining heart rate monitoring capability. The motor current signal contains cardiac cycle information that can be processed to determine heart rate, thus removing the additional hardware requirement.
Solution Approach 2:
The VAD motor control circuitry is made multi-functional by enabling it to perform both its primary function (controlling the blood pump motor) and the secondary function (detecting heart rate). The same circuit that drives the motor also senses the motor current signal, which is then analyzed to extract cardiac cycle information. This universal approach allows one system to serve multiple purposes, reducing overall device complexity.
2Reliability
If ECG electrodes are used for heart rate monitoring, then heart rate detection reliability is improved, but ease of operation deteriorates due to additional patient equipment requirements
Solution Approach 1:
The VAD system performs self-service by using its own motor current signal for heart rate detection. The system does not require external ECG electrodes or additional patient equipment because the motor current inherently contains the cardiac cycle information needed for heart rate monitoring. The VAD essentially monitors itself, eliminating the need for separate monitoring hardware and simplifying patient care.
3Device complexity
If motor current signal analysis is used to determine heart rate, then device complexity is reduced, but measurement precision may deteriorate compared to ECG signals
Solution Approach 1:
The patent introduces signal filtering and event detection algorithms as intermediaries between the raw motor current signal and the heart rate determination. These processing steps act as mediators that extract the cardiac cycle information from the motor current signal, ensuring accurate heart rate measurement despite the indirect nature of the measurement. The filtering and event detection processes enhance the reliability of the derived heart rate data.
Data Source
AI summary
The present disclosure provides for methods and systems for determining heart rate of a patient. Based on motor current signals of a ventricular assist device (VAD), each of first, second and third events in the measured current signal may be detected, the first event being indicative of a rise or fall in the current signal, the second event being indicative of a rise or fall in the current signal in the opposite direction as the first event, and the third event being indicative of a rise or fall in the current signal in the same direction as the first event. A timer counter may be initiated upon detection of the first event, and an elapsed time may be measured upon detection of the third event. Heart rate may be determined based on the elapsed time of the timer counter.