Cardiac Pacing Unwanted Stimulation Detection

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Solution Overview

Problem

Cardiac rhythm management devices often cause unwanted stimulation of skeletal muscles, such as the phrenic nerve, leading to discomfort and inefficiencies in heart pacing due to the proximity of pacing electrodes to the nerve, which results in involuntary diaphragmatic contractions similar to hiccups.

Innovation Solution

The system detects phrenic nerve stimulation through frequency domain analysis using sensors and processing circuits that generate pacing pulses to minimize nerve stimulation while ensuring heart capture, by identifying dominant frequency components and time windows associated with phrenic nerve stimulation and adjusting pacing parameters accordingly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pacing pulse energy is increased to ensure heart capture, then reliability of cardiac stimulation is improved, but unwanted phrenic nerve stimulation increases causing patient discomfort

Engineering Contradiction:

Improveheart capture reliabilityVSAvoidphrenic nerve stimulation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system uses accelerometers to detect diaphragmatic contractions caused by phrenic nerve stimulation and feeds this information back to the pacemaker controller. The controller then adjusts pacing parameters in real-time to eliminate unwanted stimulation while maintaining effective heart capture, resolving the contradiction between reliability and harmful effects.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically changes pacing parameters such as pulse amplitude, width, and configuration based on detected phrenic nerve stimulation. By adjusting these parameters, the system maintains reliable heart capture while minimizing unwanted nerve stimulation, thus resolving the technical contradiction.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If pacing electrodes are positioned closer to the heart for effective stimulation, then pacing efficiency is improved, but proximity to phrenic nerve increases causing unwanted stimulation

Engineering Contradiction:

Improvepacing efficiencyVSAvoidphrenic nerve stimulation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system dynamically adjusts pacing parameters based on real-time detection of phrenic nerve stimulation through accelerometers. This allows the system to maintain effective heart stimulation with optimized electrode positioning while actively compensating for unwanted nerve stimulation, resolving the contradiction between productivity and harmful factors.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If standard pacing protocols are used without detection mechanisms, then device complexity is minimized, but patient comfort and pacing effectiveness deteriorate due to unwanted muscle contractions

Engineering Contradiction:

Improvepacing system complexityVSAvoidpatient comfort

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The system introduces accelerometers as intermediary sensors to detect phrenic nerve stimulation. These sensors provide feedback to the pacemaker controller, enabling automatic adjustment of pacing parameters to eliminate unwanted muscle contractions and improve patient comfort while maintaining acceptable device complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This approach effectively reduces unwanted phrenic nerve stimulation during cardiac pacing, enhancing the efficiency of heart stimulation and patient comfort by optimizing pacing pulse energy and configuration to achieve heart capture without unnecessary muscle contractions.

Implementation Method 1

a sensor for sensing a response to a stimulation of a phrenic nerve of the patient and to produce a corresponding sensor signal

Methodology Applied

Scientific EffectMechanical sensing:

Implementation Method 2

derive a time-frequency representation of the sensor signal based on the received sensor signal using wavelets; identify a dominant frequency component in the time-frequency representation of the sensor signal

Methodology Applied

Scientific EffectWavelet transformation:

Data Source

PatentUS9795790B2Unwanted stimulation detection during cardiac pacing

Publication Date: 2017.10.24 CARDIAC PACEMAKERS INC

AI summary

The disclosure relates to systems and methods for cardiac rhythm management. In some cases, a system may include a pulse generator for generating pacing pulses for stimulating a heart of a patient; a memory; and a sensor configured to sense a response to an unwanted stimulation and to produce a corresponding sensor signal. A processing circuit may receive the sensor signal for a time after one or more pacing pulses, and may derive a time-frequency representation of the sensor signal based on the received sensor signal. The processing circuit may use the time-frequency representation of the sensor signal to help identify unwanted stimulation. Once unwanted stimulation is detected, the processing circuit may change the pacing pulses to help reduce or eliminate the unwanted stimulation.