Implant Lead Two-Wire Signaling for Safe Electrode Control
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Solution Overview
Problem
Implantable medical devices with multiple electrodes and sensors face challenges in safely and reliably managing complex configurations without modifying existing generator hardware, particularly in distinguishing between stimulation and control impulses to avoid inappropriate cardiac tissue depolarization.
Innovation Solution
An active implantable medical device system with a generator and lead configuration that uses a two-wire connection for digital data communication, including a control circuit to recognize distinctive micro-impulses for controlling switches and isolating electrodes from the connection, allowing safe and adaptable operation of multiple electrodes and sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiplexing systems with multiple electrodes and sensors are integrated into the lead, then the functionality and versatility of the implantable medical device are improved, but the complexity of managing multiple electrodes and distinguishing between stimulation and control signals increases
Solution Approach 1:
The patent segments the control signals into distinct types (stimulation impulses vs. control impulses) with unique identifying characteristics. Each impulse type has specific form factors including duration, amplitude, and waveform shape that allow the control circuit to differentiate and route them appropriately, managing complexity through systematic classification
Solution Approach 2:
The control circuit acts as an intermediary between the two-wire connection and the multiple electrodes/sensors. It receives all signals through the two-wire connection, identifies their type based on form characteristics, and selectively connects them to the appropriate electrodes or sensors via controlled switches, thereby managing the complexity of multiple connections
2Ease of operation
If control signals are transmitted through the same two-wire connection as stimulation impulses, then the ease of operation and adaptability are improved, but the risk of inappropriate cardiac tissue depolarization due to signal confusion increases
Solution Approach 1:
The control circuit performs preliminary identification of incoming impulses based on their form characteristics (duration, amplitude, waveform) before routing them to electrodes. This preliminary discrimination prevents misinterpretation of control signals as stimulation impulses, thereby preventing harmful inappropriate cardiac tissue depolarization
Solution Approach 2:
The patent uses distinct parameter values for different impulse types: control impulses have specific duration ranges (e.g., 1-10 microseconds), amplitude levels, and waveform characteristics that differ from stimulation impulses. These parameter changes enable reliable differentiation and prevent harmful signal confusion
3Reliability
If switches are used to selectively connect electrodes to the two-wire connection for control signals, then the reliability and safety are improved, but the device complexity increases
Solution Approach 1:
The control circuit performs preliminary identification and classification of incoming impulses before switching connections. By determining the impulse type (control vs. stimulation) in advance based on form characteristics, the circuit can safely activate the appropriate switch, ensuring reliability while managing complexity through sequential decision-making
Data Source
AI summary
An active implantable medical device including bidirectional communications between a generator and sensors or actuators located at the distal extremity of a lead. A lead (14) is connected at its proximal end to a generator (10) and has at the distal end electrodes (38, 42) able to come in contact with surrounding tissues. A two-wire connection (34, 36) connects these electrodes to the generator. The lead incorporates transducers (24, 26) of sensor or actuator type. The generator includes circuits for sending and receiving digital data (46,48,50,54,56) capable of producing instructions to one of the transducers and to receive and decode information from one of the transducers in response to a specific instruction produced by the generator. The transducer is able to receive, decode and carry out the aforementioned controls, as well as send data in response.