Modulated High-Frequency Electrical Stimulation Pulses
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Solution Overview
Problem
Medical devices delivering electrical stimulation therapy often cause discomfort or pain due to extraneous stimulation of non-targeted tissues, such as skeletal muscle or nerves, especially when electrodes are positioned extra-cardiac or extracardiovascular and not in direct contact with the targeted tissue.
Innovation Solution
A medical device that generates modulated high-frequency electrical stimulation pulses by varying the frequency and bias of the pulse signal within the pulse width, minimizing extraneous stimulation through targeted depolarization of cardiac, muscle, or nerve tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high frequency electrical stimulation pulses are delivered to treat cardiac arrhythmias, then therapeutic effect is improved, but extraneous stimulation of non-targeted tissue (skeletal muscle, nerves) causes patient discomfort or pain
Solution Approach 1:
The patent applies dynamics by modulating the frequency of electrical stimulation pulses during the pulse width. The frequency is varied between a minimum frequency (e.g., 50-200 Hz) and a maximum frequency (e.g., 500-2000 Hz) to achieve targeted cardiac stimulation while minimizing extraneous tissue activation. This dynamic frequency adjustment allows the stimulation to adapt during the pulse duration, capturing cardiac tissue effectively while reducing perception by sensory nerves.
Solution Approach 2:
The patent changes physical parameters of the electrical stimulation pulse, specifically the frequency parameter, to resolve the contradiction. By modulating frequency between minimum and maximum values during the pulse width, and adjusting pulse amplitude and width parameters, the system achieves effective cardiac capture while staying below the threshold for painful sensory nerve activation. This parameter modulation transforms a static stimulation approach into a dynamic one that selectively targets different tissue types.
2Device complexity
If electrodes are positioned extra-cardiac or extracardiovascular for therapy delivery, then device complexity is reduced, but extraneous tissue stimulation increases causing discomfort
Solution Approach 1:
The patent uses frequency modulation as an intermediary mechanism to differentiate between targeted and non-targeted tissue responses. By varying frequency during the pulse width, the system creates a selective stimulation pattern that preferentially activates cardiac tissue while minimizing activation of skeletal muscle and sensory nerves. This intermediary modulation approach allows extra-cardiac electrode positioning without the usual penalty of extraneous stimulation.
Solution Approach 2:
The dynamic frequency modulation during pulse width creates a time-varying stimulation pattern that exploits differences in tissue excitability thresholds and response characteristics. Cardiac tissue responds effectively to the modulated frequency pattern, while sensory nerves and skeletal muscle remain below their activation thresholds, enabling simplified electrode positioning without increased discomfort.
3Reliability
If electrical stimulation amplitude is increased to ensure cardiac capture, then therapeutic reliability is improved, but perception and discomfort by patient increases
Solution Approach 1:
The patent employs periodic frequency modulation within the pulse width, creating a pattern of oscillating stimulation intensity. This periodic variation allows the stimulation to remain below the threshold for painful sensory nerve activation while still achieving effective cardiac capture through cumulative effect. The modulated pattern delivers therapeutic benefit without triggering the high-threshold pain receptors.
Solution Approach 2:
Instead of simply increasing amplitude, the patent changes the frequency parameter dynamically during the pulse. This parameter transformation allows the system to achieve cardiac capture through frequency-selective stimulation rather than amplitude escalation, keeping the stimulation perceptible to cardiac tissue but not to sensory nerves.
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 modulated pulse delivery reduces patient discomfort and perception of electrical stimulation, enabling a wider range of therapeutic options for arrhythmias while minimizing extraneous tissue activation.
Implementation Method 1
The modulator is configured to modulate the frequency of oscillations of the electrical stimulation pulse signal between a minimum frequency and a maximum frequency during the pulse width
Implementation Method 2
The modulator is configured to modulate the bias of the electrical stimulation pulse signal between a minimum offset and a maximum offset during the pulse width
Implementation Method 3
minimizing extraneous stimulation through targeted depolarization of cardiac, muscle, or nerve tissue
Data Source
AI summary
A medical device is configured to deliver therapeutic electrical stimulation pulses by generating frequency modulated electrical stimulation pulse signals. The medical device includes a pulse signal source and a modulator. The pulse signal source generates an electrical stimulation pulse signal having a pulse width. The modulator may include a high frequency modulator configured to modulate a frequency of the pulse signal from a starting frequency down to a minimum frequency during the pulse width. The modulator may include a low frequency bias generator to modulate the offset of the pulse signal between a minimum offset and a maximum offset in other examples.