Cardiac Localization System Noise Tolerant Interleaved Impedance Measurements
Solution Overview
Problem
Impedance-based medical localization systems are prone to noise interference from magnetic field-based systems, especially when these systems operate continuously, leading to inaccurate position measurements of medical devices within the body.
Innovation Solution
A position sensing and navigation system that simultaneously applies unique drive signals with orthogonal modulation frequencies to electrodes, allowing for continuous impedance measurements while pausing data input during magnetic noise generation, thereby reducing noise and maintaining measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the magnetic field-based localization system operates continuously, then the positioning capability is maintained, but noise is induced into the impedance-based measurements
Solution Approach 1:
The patent implements periodic action by temporally alternating the operation of the magnetic field-based localization system with the impedance-based measurements. The magnetic field system is activated during specific time intervals when impedance measurements are not being taken, and deactivated during intervals when impedance measurements are required. This periodic operation allows the magnetic field system to maintain positioning capability while preventing noise induction into impedance measurements, as the harmful magnetic field operation is separated in time from the vulnerable impedance measurement periods.
2Productivity
If the impedance-based localization system operates continuously, then measurement continuity is maintained, but noise from magnetic field operations cannot be avoided
Solution Approach 1:
The patent applies periodic action by establishing a temporal alternation schedule where the impedance-based localization system operates continuously during intervals when the magnetic field system is inactive, and the magnetic field system operates during intervals when impedance measurements are suspended. This allows the impedance system to maintain measurement continuity during its active periods while the magnetic field system operates periodically without interfering with impedance measurements, thus resolving the contradiction between continuous operation and noise avoidance.
3Object-affected harmful factors
If temporal alternation of systems is implemented, then noise in impedance measurements is reduced, but system operation complexity increases
Solution Approach 1:
The patent implements feedback by incorporating a controller that receives signals from both the impedance-based localization system and the magnetic field-based localization system. The controller monitors the operational states of both systems and automatically manages the temporal alternation between them. It detects when impedance measurements are being taken and accordingly activates or deactivates the magnetic field system, and vice versa. This feedback-based automatic control simplifies the overall system operation complexity by removing the need for manual coordination between systems, while still achieving noise reduction through temporal alternation.
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 minimizes noise in impedance measurements, maintains continuous operation of the impedance-based localization system, and reduces crosstalk between systems, resulting in more accurate device localization within the body.
Implementation Method 1
impedance-based measurement of electrodes of a medical device in conjunction with magnetic-based measurement of magnetic sensors of the medical device
Implementation Method 2
a magnetic field generator may create a magnetic field within the body and to control the strength, orientation, and frequency of the field
Implementation Method 3
current or voltage measurements for one or more magnetic position sensors (e.g., magnetic field sensors) associated with the catheter are obtained
Data Source
AI summary
The present disclosure is directed to interleaving electrical noise generating operations with impedance measurements in a medical localization system. The systems and methods continuously and simultaneously provide unique frequency drive signals, which are harmonics of a common base frequency, across electrode patches to generate an electrical field. Response signals electrodes in the electric field are measured and synchronously demodulated. A demodulated data stream is then filtered (e.g., decimated) to generate impedance-based values proportional to the location of the electrode for each unique frequency. The demodulated data stream into the filter is paused to allow operation of an electrical noise generating device such a magnetic field-based localization system. More specifically, the data stream is paused for a time period equal to an integer multiple of a base period of the common base frequency. This allows resuming filtering of the demodulated data stream free of any frequency discontinuity.