Autothreshold Pacing with Common Electrode Sensing
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Solution Overview
Problem
Implantable medical devices (IMDs) face challenges in determining the optimal pacing stimulation energy for the heart, as existing methods struggle when a sensing electrode independent from the pacing electrodes is unavailable, leading to difficulties in accurately detecting cardiac capture and potentially causing unnecessary heart stress or battery life issues.
Innovation Solution
The implementation of a system with a therapy circuit, cardiac signal sensing circuit, and control circuit that initiates a first threshold test mode to determine the optimum electrostimulation energy for heart chamber capture, using a sensing electrode common to the pacing electrodes and adjusting the energy delivery to find the minimum required for cardiac depolarization, even when an independent sensing electrode is not available.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensing electrode independent from the pacing electrodes is unavailable, then the device cannot accurately detect cardiac capture, but using a common electrode introduces measurement interference from pacing artifacts
Solution Approach 1:
The system dynamically switches between different threshold test modes (first mode using common electrode with artifact rejection, second mode using independent electrode) based on electrode availability and pacing configuration. The control circuit adapts the sensing strategy in real-time to optimize measurement accuracy while avoiding artifact interference.
Solution Approach 2:
The patent introduces an intermediary signal processing approach where the sensing circuit detects cardiac capture signals while the control circuit simultaneously identifies and rejects pacing artifacts through template matching and signal subtraction techniques. This intermediary processing layer enables accurate capture detection despite using a common electrode.
2Reliability
If pacing stimulation energy is increased to ensure cardiac capture, then therapy delivery is reliable, but heart stress increases and battery life decreases
Solution Approach 1:
The system performs automatic threshold tests to determine the minimum pacing energy required for reliable cardiac capture. The control circuit uses feedback from sensed cardiac signals to identify the capture threshold and automatically programs the pacing stimulus to deliver energy at or near this threshold, ensuring reliable capture while minimizing energy consumption and extending battery life.
Solution Approach 2:
The patent changes the energy parameter of pacing stimulation from fixed high energy to dynamically adjusted energy levels based on individually determined capture thresholds for each patient and each pacing electrode, optimizing the balance between capture reliability and energy conservation.
3Use of energy by moving object
If pacing stimulation energy is decreased to conserve battery life, then energy consumption is reduced, but cardiac capture reliability decreases
Solution Approach 1:
The patent replaces the traditional mechanical approach of using fixed high-energy pacing pulses with a sophisticated electronic control system that automatically determines and adjusts pacing energy levels. The control circuit uses signal processing algorithms to identify capture events and programmatically sets optimal energy levels, substituting electronic intelligence for conservative energy margins.
4Adaptability or versatility
If a first threshold test mode uses a common electrode for sensing, then the device can determine optimal pacing energy without independent sensing electrodes, but the measurement is affected by pacing artifacts
Solution Approach 1:
The system dynamically adapts between different threshold test modes based on electrode availability. When independent sensing electrodes are unavailable, the control circuit activates the first threshold test mode using common electrodes with artifact rejection algorithms. When independent electrodes are available, it switches to the second threshold test mode for cleaner signal acquisition, optimizing both versatility and measurement precision.
Data Source
AI summary
Cardiac electrostimulation energy is delivered to a heart chamber of a subject according to a normal pacing mode using a set of implantable pacing electrodes. When a threshold test for the heart chamber is initiated and a sensing electrode independent from the set of pacing electrodes is unavailable for the heart chamber, cardiac electrostimulation energy is delivered to the subject according to a threshold test mode. The threshold test mode includes sensing a cardiac activity signal from a subject using a set of sensing electrodes that includes an electrode common to the set of pacing electrodes, and changing the electrostimulation energy and sensing a resulting cardiac activity signal using the set of sensing electrodes to determine the optimum electrostimulation energy for capture of the heart chamber.