Pulse Voltage Regulator Mode Switching for MRI Pacing
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Solution Overview
Problem
Implantable cardiac stimulation devices, such as pacemakers and AICDs, face challenges in delivering effective pacing energy to the heart due to attenuation by strong RF signals, particularly during MRI scans, which reduces the energy delivered to the heart.
Innovation Solution
An implantable cardiac stimulation device with a pulse generator that includes a pulse voltage regulator and additional electronic circuitry, capable of operating in a second enhanced energy mode where the supply voltage is gated by the pacing signal, allowing for higher voltage levels and increased energy delivery to the heart even in the presence of RF signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pulse voltage regulator is used to generate pacing pulses, then the device operates with standard voltage levels, but the delivered energy is reduced significantly in the presence of strong RF signals
Solution Approach 1:
The pulse generator dynamically switches between two operating modes based on detected RF signal presence. In the first mode, the pulse voltage regulator operates normally. In the second mode, the supply voltage is directly coupled to the pacing output node to deliver enhanced energy, allowing the system to adapt to changing electromagnetic environments
Solution Approach 2:
The system changes the voltage parameter by switching from regulated voltage output to direct supply voltage coupling. This parameter change enables the pacing pulses to overcome RF signal attenuation and maintain sufficient energy delivery to the heart during MRI scans
2Power
If the pulse generator operates in enhanced energy mode with direct supply voltage coupling, then sufficient energy is delivered during RF interference, but the device complexity increases
Solution Approach 1:
The pulse generator is segmented into distinct operating modes with separate circuit paths. The routing circuitry divides the operation into first mode (pulse voltage regulator output) and second mode (supply voltage direct coupling), allowing the system to use simpler circuitry when needed and complex circuitry only when RF interference is detected
Data Source
AI summary
Example implantable cardiac stimulation devices, pulse generators, and methods providing enhanced cardiac pacing energy are disclosed herein. In an example, an implantable cardiac stimulation device may include a pulse generator having a pacing output node providing cardiac pacing pulses to be applied to a heart of a patient. The pulse generator may include a pulse voltage regulator that receives a pacing signal and generates cardiac pacing pulses at an output of the pulse voltage regulator according to the pacing signal. The pulse voltage regulator may receive a supply voltage to generate cardiac pacing pulses at the supply voltage, gated by the pacing signal. The pulse generator may further include routing circuitry to route the output of the pulse voltage regulator to the pacing output node of the pulse generator while the pulse generator is in a first operating mode, and to route the supply voltage, gated by the pacing signal, to the pacing output node of the pulse generator while the pulse generator is in a second operating mode.