Method of improving the quality of an electrocardiogram obtained from a patient undergoing magnetic resonance imaging
First Claim
1. A method of improving the quality of electrocardiogram (ECG) signals for input to a cardiac monitor and obtained from a patient undergoing magnetic resonance imaging (MRI) wherein the ECG leads attached to the patient are exposed to changing magnetic fields produced by the MRI which induce relatively high levels of rapid voltage changes in the ECG leads, comprising:
- conducting the ECG signals having MRI induced noise signals superimposed therein to the input of a slew rate limiter (SRL) circuit having a preselected maximum slew rate, the circuit providing an output signals having a maximum dv/dt which is slightly greater than the maximum typical ECG dv/dt;
amplifying the ECG signal having the MRI induced noise superimposed thereon;
connecting the amplified output of the SRL circuit to the input of a low pass filter (LPF) circuit having attenuation above the ECG typical fundamental frequency; and
connecting the output of the LPF circuit to a cardiac monitor, wherein said step of amplifying the ECG signal having the MRI induced noise superimposed thereon has a gain of X and wherein said SRL maximum slew rate dv/dt is about 0.3 X v/sec.
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Abstract
A method for improving the quality of electrocardiogram (ECG) signals for input to a cardiac monitor and obtained from a patient undergoing magnetic resonance imaging (MRI) wherein the ECG leads attached to the patient are exposed to rapidly changing magnetic fields produced by the MRI which induce relatively high levels of rapid voltage changes in the ECG leads, the method including the steps of conducting the ECG signals having MRI induced noise signals superimposed thereon to the input of a slew rate limiter (SRL) circuit having a preselected maximum slew rate, the circuit providing an output signal having a maximum dv/dt which is slightly greater than the maximum typical ECG dv/dt, connecting the output of the SRL circuit to the input of a low pass filter circuit having an attenuation above the ECG typical fundamental frequency and connecting the output of the low pass filter circuit to a cardiac monitor.
94 Citations
2 Claims
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1. A method of improving the quality of electrocardiogram (ECG) signals for input to a cardiac monitor and obtained from a patient undergoing magnetic resonance imaging (MRI) wherein the ECG leads attached to the patient are exposed to changing magnetic fields produced by the MRI which induce relatively high levels of rapid voltage changes in the ECG leads, comprising:
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conducting the ECG signals having MRI induced noise signals superimposed therein to the input of a slew rate limiter (SRL) circuit having a preselected maximum slew rate, the circuit providing an output signals having a maximum dv/dt which is slightly greater than the maximum typical ECG dv/dt; amplifying the ECG signal having the MRI induced noise superimposed thereon; connecting the amplified output of the SRL circuit to the input of a low pass filter (LPF) circuit having attenuation above the ECG typical fundamental frequency; and connecting the output of the LPF circuit to a cardiac monitor, wherein said step of amplifying the ECG signal having the MRI induced noise superimposed thereon has a gain of X and wherein said SRL maximum slew rate dv/dt is about 0.3 X v/sec. - View Dependent Claims (2)
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Specification
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- Resources
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Current AssigneeInvivo Research Incorporated Tulsa OK
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Original AssigneeInvivo Research Inc. (Safetytek Corp)
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InventorsMoore, John C.
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Primary Examiner(s)Cohen, Lee S.
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Assistant Examiner(s)SCHAETZLE, KENNEDY
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Application NumberUS07/330,773Time in Patent Office684 DaysField of Search128/696, 128/653, 324/322US Class Current600/509CPC Class CodesA61B 5/055 involving electronic [EMR] ...A61B 5/30 Input circuits thereforA61B 5/308 for electrocardiography [ECG]
