Composite Pacing Pulse Generation via Capacitor Array Segmentation
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Solution Overview
Problem
Existing implantable medical devices (IMDs) face challenges in delivering effective cardiac pacing pulses using extra-cardiovascular electrodes, as the pulse voltage amplitude required to capture the heart may exceed acceptable comfort levels for patients, and the long pulse width needed can exceed the capacity of typical low voltage pacing capacitors due to fast decay rates.
Innovation Solution
The implementation of a medical device system that generates a composite pacing pulse by delivering a series of fused low voltage electrical pulses using extra-cardiovascular electrodes. This system employs a capacitor array with multiple capacitors, selectively coupling different portions of the capacitors to an output signal line to generate individual pulses with varying effective capacitance and decay rates, thereby producing a composite pulse with adequate cumulative energy to capture the heart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage pacing pulses are delivered using extra-cardiovascular electrodes to capture the heart, then the pacing effectiveness is improved, but the patient comfort deteriorates due to excessive voltage amplitude
Solution Approach 1:
The pacing pulse is segmented into multiple lower-voltage sub-pulses delivered in rapid succession. Instead of delivering one high-voltage pulse, the system delivers a series of pulses with individually lower amplitudes that collectively achieve cardiac capture while maintaining patient comfort.
Solution Approach 2:
The system employs periodic delivery of multiple pacing pulses within a defined composite pulse width. The pulses are delivered at specific intervals (e.g., 100-500 Hz repetition rate) to accumulate electrical charge effect on cardiac tissue while maintaining low individual pulse amplitudes.
2Reliability
If long pulse width is used to deliver adequate energy to capture the heart with extra-cardiovascular electrodes, then the pacing effectiveness is improved, but the capacitor capacity requirement increases beyond typical low voltage pacing capacitor limits
Solution Approach 1:
The total pulse width is segmented into multiple shorter sub-pulse durations. Instead of requiring one long-duration pulse that exceeds capacitor capabilities, the system delivers multiple shorter pulses (e.g., 200-500 microseconds each) in sequence, where each pulse is within the capacitor's delivery capability.
Solution Approach 2:
Multiple pacing pulses are delivered periodically within the composite pulse width timeframe. The repetition rate and number of pulses are configured so that the cumulative energy delivery achieves capture threshold while each individual pulse duration remains within capacitor specifications.
3Adaptability or versatility
If multiple capacitors are selectively coupled to generate composite pacing pulses with varying decay rates, then the pacing versatility is improved, but the device complexity increases
Solution Approach 1:
The capacitor bank is segmented into multiple discrete capacitor elements that can be independently selected and coupled. This allows the system to create different effective capacitance values by combining different numbers and configurations of individual capacitors, enabling customized decay rates for different pacing scenarios.
Solution Approach 2:
The capacitor configuration is dynamically adjustable during operation. The control circuitry can selectively couple different capacitor combinations based on real-time pacing requirements, allowing adaptation of pulse decay characteristics without requiring manual reconfiguration or multiple fixed capacitor banks.
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
The technique allows for the successful pacing of the heart using extra-cardiovascular electrodes, even when individual pulse energies are below the capture threshold, by extending the pulse width and maintaining a low enough pulse amplitude to be comfortable for the patient.
Implementation Method 1
A therapy module 85 may include a capacitor array 110 including multiple capacitors C1-Cn
Implementation Method 2
A composite pacing pulse delivered using extra-cardiovascular electrodes may capture the heart when the cumulative pulse energy of the individual pulses exceeds a capture threshold of the heart
Data Source
AI summary
An implantable medical device has a therapy module configured to generate a composite pacing pulse including a series of at least two individual pulses. The therapy module is configured to generate the composite pacing pulse by generating a first pulse of the at least two individual pulses by selectively coupling a first portion of a plurality of capacitors to an output signal line and generate a second pulse of the at least two individual pulses by selectively coupling a second portion of the plurality of capacitors to the output signal line.