Slew Rate Detection in Wireless Cardiac Pacing Receivers
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Solution Overview
Problem
Conventional implantable wireless electrodes fail to distinguish between ultrasound energy signals intended for cardiac pacing and those used for diagnostic or therapeutic purposes, leading to unintended stimulation of the heart during procedures like ultrasound imaging.
Innovation Solution
The implementation of a receiver-stimulator system with a circuit that includes a slew rate detector and pulse duration detector to differentiate between cardiac pacing signals and other ultrasound energy signals, blocking or limiting signals with rates or durations outside predetermined thresholds from being delivered to the heart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wireless electrode is used to receive ultrasound energy for cardiac pacing, then effective endocardial pacing is achieved, but unintended stimulation occurs during diagnostic ultrasound procedures
Solution Approach 1:
The patent applies parameter changes by monitoring the slew rate (rate of change of voltage) and pulse duration of received ultrasound signals. Cardiac pacing signals have specific slew rate and duration parameters that differ from diagnostic ultrasound signals. By detecting these parameter differences, the device can distinguish between intended pacing signals and unintended diagnostic signals, preventing inappropriate stimulation while maintaining effective pacing therapy.
2Adaptability or versatility
If the wireless electrode responds to all ultrasound signals, then it can be activated by any ultrasound source, but it cannot distinguish between pacing and diagnostic signals
Solution Approach 1:
The device maintains adaptability by responding to ultrasound signals in general but improves measurement precision by specifically measuring the slew rate and pulse duration parameters. These parameter measurements enable accurate differentiation between cardiac pacing signals and diagnostic ultrasound signals, allowing the electrode to selectively respond only to appropriate pacing signals while ignoring diagnostic signals.
3Ease of operation
If diagnostic ultrasound procedures are performed on patients with implanted wireless electrodes, then cardiac function can be assessed, but the ultrasound energy may inadvertently stimulate the heart
Solution Approach 1:
The patent implements feedback by continuously monitoring the characteristics of received ultrasound signals and using this information to control the switching element. When the monitored slew rate and pulse duration match those of cardiac pacing signals, the switching element enables stimulation. When they match diagnostic ultrasound characteristics, the switching element blocks stimulation. This feedback mechanism allows diagnostic procedures to be performed safely while preventing inadvertent cardiac stimulation.
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
Effectively prevents unintended electrical stimulation of the heart by accurately distinguishing between cardiac pacing signals and diagnostic or therapeutic ultrasound signals, ensuring synchronized heartbeat therapy without interference from external ultrasound procedures.
Implementation Method 1
a piezoelectric element that is enclosed by a housing and produces voltage signals delivered to the patient's body in response to receiving ultrasound energy
Data Source
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AI summary
The present technology is generally directed to implantable medical device systems configured to provide cardiac resynchronization therapy. In some embodiments, the implantable medical device system comprises a housing, electrodes carried by the housing, a transducer configured to produce input voltage signals in response to ultrasound energy, and a circuit configured to provide, via an electrical pathway, output voltage signals based on the input voltage signals. The circuit comprises a movable switch, and a slew rate detector configured to detect whether a voltage rate of an individual pulse of the input voltage signals exceeds a predetermined threshold voltage rate. The circuit is configured to move the switch to an open position in response to the detected voltage rate exceeding the predetermined threshold voltage rate.