Low-Power Admittance Measurement for Heart Failure Detection
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Solution Overview
Problem
Current methods for monitoring heart failure, such as Chronicle and Optivol/CorVue, are downstream measures that do not detect the earliest indicators of impending heart failure, and existing technologies for measuring left ventricular volume are invasive, noisy, and not suitable for chronic measurements.
Innovation Solution
A low-power apparatus that measures complex electrical admittance using a stimulator and sensor with electrodes placed in the heart, allowing for early detection of heart failure by determining left ventricular preload without major redesign of pacemakers, using existing leads and power sources, and providing a true/false warning or quantitative measure of heart volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conductance measurements are used to detect LV volume, then early detection of heart failure is enabled, but the measurements become invasive and noisy
Solution Approach 1:
The patent replaces mechanical/invasive conductance measurement systems with an electrical admittance measurement system. The admittance apparatus uses electrical fields to measure complex electrical properties (resistance and reactance) of the heart, which can be derived from voltage and current measurements taken through existing pacemaker leads. This substitution eliminates the need for invasive conductance electrodes while providing accurate LV volume measurements.
Solution Approach 2:
The patent introduces complex electrical admittance as an intermediary parameter that mediates between the electrical measurements available through pacemaker leads and the physiological parameter of LV volume. By measuring admittance (which includes both resistive and reactive components) and using signal processing to separate blood and muscle components, the system can non-invasively determine LV volume without direct mechanical contact.
2Measurement precision
If admittance apparatus is added to pacemakers to measure complex electrical properties, then early warning for heart failure is enabled, but device complexity increases
Solution Approach 1:
The patent makes the existing pacemaker leads multi-functional by enabling them to serve both their original pacing function and the new admittance measurement function. The same leads that deliver electrical pulses for pacing are also used to measure voltage and current for admittance calculations. This universality approach allows heart failure monitoring to be added without requiring separate dedicated measurement leads, thereby limiting the increase in device complexity.
Solution Approach 2:
The pacemaker system performs self-diagnosis and self-monitoring by using its own existing components (leads, power source, processing unit) to measure admittance and detect heart failure. The system leverages its existing electrical output and measurement capabilities to monitor its own performance and detect physiological changes, eliminating the need for external monitoring devices and reducing overall system complexity.
3Duration of action of stationary object
If continuous measurements are made to monitor heart volume, then continuous monitoring capability is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic admittance measurements rather than continuous measurements. The system performs measurements at specific intervals or triggered by pacemaker firing events, during which the admittance apparatus is activated, and remains in a low-power state between measurements. This periodic operation enables continuous monitoring capability over extended periods while significantly reducing average power consumption compared to continuous operation.
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
Enables early detection of heart failure, reduces hospital admissions, and improves heart pumping efficiency by providing accurate and continuous measurements of heart volume, stroke volume, and pressure-volume relationships, while being small in size and low in power consumption.
Implementation Method 1
stimulating with a stimulator disposed in a housing disposed in the patient with two or more electrodes disposed in the patient with either current or voltage
Implementation Method 2
sensing with a sensor disposed in the housing with two or more sensing electrodes disposed in the patient to sense a response from the sensing electrodes based on the stimulation of the stimulating electrodes
Implementation Method 3
determining with a signal processor disposed in the housing and in electrical communication with both the stimulator and the sensor the complex electrical admittance and/or complex electrical impedance of the patient
Data Source
AI summary
An apparatus for measuring complex electrical admittance and/or complex electrical impedance in animal or human patients includes a first electrode and at least a second electrode which are adapted to be disposed in the patient. The apparatus includes a housing adapted to be disposed in the patient. The housing has disposed in it a stimulator in electrical communication with at least the first electrode to stimulate the first electrode with either current or voltage, a sensor in electrical communication with at least the second electrode to sense a response from the second electrode based on the stimulation of the first electrode, and a signal processor in electrical communication with the sensor to determine the complex electrical admittance or impedance of the patient.