Vagal Stimulation System Reducing Pain via Inverted Fiber Recruitment
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Solution Overview
Problem
Current methods for vagal nerve stimulation often cause adverse pain, discomfort, or damage due to the unnatural recruitment order of nerve fibers and lack of control over stimulation parameters, which can lead to heart rate fluctuations and neuropathic pain.
Innovation Solution
A vagal stimulation system using a multipolar electrode device applied to the vagus nerve with a control unit that configures stimulation to minimize pain by applying bursts of pulses with specific pulse repetition intervals, synchronizing with cardiac cycles, and incorporating ramping techniques to gradually adjust stimulation parameters, thereby mimicking natural nerve fiber recruitment and reducing adverse effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional vagal nerve stimulation is applied to treat heart conditions, then heart rate can be reduced, but pain and discomfort are caused due to unnatural nerve fiber recruitment order
Solution Approach 1:
The patent inverts the conventional stimulation approach by reversing the natural recruitment order of nerve fibers. Instead of stimulating larger diameter fibers first (which causes pain), the system stimulates smaller diameter fibers first, then progressively activates larger fibers. This inversion of the stimulation sequence eliminates pain while maintaining effective heart rate control through vagal nerve activation.
Solution Approach 2:
The patent employs dynamic adjustment of stimulation parameters including pulse amplitude, pulse width, and frequency in a progressive manner. The system dynamically increases stimulation intensity in controlled steps rather than applying maximum intensity abruptly, allowing the nervous system to adapt gradually. This dynamic progression from low to high intensity stimulation eliminates pain while achieving effective heart rate reduction.
2Reliability
If high intensity vagal stimulation is applied to achieve effective heart rate reduction, then therapeutic effect is improved, but neuropathic pain and tissue damage risk increase
Solution Approach 1:
The patent applies preliminary action by first establishing a baseline of effective vagal stimulation at low intensity before progressively increasing to higher intensities. The system initially activates at a threshold level sufficient to achieve therapeutic heart rate reduction, then gradually increases intensity only as needed. This preliminary establishment of effective stimulation at safe levels prevents the sudden onset of high intensity that causes pain and tissue damage.
Solution Approach 2:
The patent systematically changes multiple stimulation parameters including pulse amplitude, pulse width, and frequency in a coordinated progressive manner. Rather than abruptly increasing any single parameter to high intensity, the system modifies parameters step-by-step, maintaining therapeutic effectiveness while keeping intensity within pain-free ranges. This multi-parameter progressive adjustment achieves therapeutic effects without generating neuropathic pain or tissue damage.
3Speed
If abrupt stimulation is applied to quickly reduce heart rate, then rapid therapeutic response is achieved, but heart rate fluctuations and discomfort occur
Solution Approach 1:
The patent implements periodic action through rhythmic, cyclic vagal stimulation patterns that mirror natural physiological rhythms. The system applies stimulation in repeated cycles with controlled intervals, allowing the heart rate to gradually respond to each cycle rather than being subjected to a single abrupt stimulus. This periodic approach achieves progressive heart rate reduction while maintaining stability and preventing fluctuations.
Solution Approach 2:
The patent employs dynamic, adaptive adjustment of stimulation timing and intensity in response to real-time heart rate feedback. The system dynamically modulates stimulation parameters to match the heart's natural rhythm, progressively accelerating heart rate reduction without causing abrupt changes. This dynamic adaptation maintains heart rate stability while achieving timely therapeutic response.
4Productivity
If stimulation parameters are rapidly adjusted to optimize treatment, then treatment efficiency is improved, but patient comfort and tolerance decrease
Solution Approach 1:
The patent employs dynamic, progressive adjustment of stimulation parameters in a coordinated manner. The system simultaneously modifies pulse amplitude, pulse width, and frequency in a controlled sequence that prioritizes patient comfort. Parameters are adjusted in small incremental steps rather than abrupt changes, allowing the patient's nervous system to adapt gradually. This dynamic progressive adjustment maintains treatment efficiency while ensuring continuous patient comfort and tolerance.
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 system effectively reduces heart rate and minimizes pain by mimicking natural nerve fiber recruitment, reducing the likelihood of heart rate fluctuations and preventing neuropathic pain through controlled and gradual adjustment of stimulation parameters.
Implementation Method 1
The use of nerve stimulation for treating and controlling a variety of medical, psychiatric, and neurological disorders has seen significant growth over the last several decades. In particular, stimulation of the vagus nerve (the tenth cranial nerve, and part of the parasympathetic nervous system) has been the subject of considerable research.
Implementation Method 2
The control unit configures: (a) a pulse repetition interval (PRI) within each of the multi-pulse bursts to be on average at least 20 ms, such as at least 30 ms, e.g., at least 50 ms, and (b) the burst duration to be less than 75% of the interburst interval
Data Source
AI summary
Apparatus is provided including an electrode device and a control unit. The electrode device is configured to be coupled to a site of a subject selected from the group consisting of: a vagus nerve, an epicardial fat pad, a pulmonary vein, a carotid artery, a carotid sinus, a coronary sinus, a vena cava vein, a right ventricle, a right atrium, and a jugular vein. The control unit is configured to drive the electrode device to apply to the site a current in at least first and second bursts, the first burst including a plurality of pulses, and the second burst including at least one pulse, and set (a) a pulse repetition interval (PRI) of the first burst to be on average at least 20 ms, (b) an interburst interval between initiation of the first burst and initiation of the second burst to be less than 10 seconds, (c) an interburst gap between a conclusion of the first burst and the initiation of the second burst to have a duration greater than the average PRI, and (d) a burst duration of the first burst to be less than a percentage of the interburst interval between, the percentage being less than 67%. Other embodiments are also described.