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Questions and Answers
What is the meaning of the acronym ECG?
What is the meaning of the acronym ECG?
Electrocardiograph
What is an Electrocardiogram?
What is an Electrocardiogram?
A tracing produced by an electrocardiograph
What is the SI unit for electrical current?
What is the SI unit for electrical current?
Amps
What is the SI unit for resistance?
What is the SI unit for resistance?
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What is the metric prefix for 10⁶ (1,000,000)?
What is the metric prefix for 10⁶ (1,000,000)?
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The following scientific notation is correct: 10⁻³ = milli
The following scientific notation is correct: 10⁻³ = milli
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Which of the following options are the components of a biopotential system? (Select all that apply)
Which of the following options are the components of a biopotential system? (Select all that apply)
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What are the two main measurements taken in an ECG?
What are the two main measurements taken in an ECG?
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A faster paper speed in an ECG will result in a shorter recording of the heart's electrical activity.
A faster paper speed in an ECG will result in a shorter recording of the heart's electrical activity.
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What is the AHA-recommended paper speed for an ECG?
What is the AHA-recommended paper speed for an ECG?
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What is the AHA recommended sensitivity for an ECG?
What is the AHA recommended sensitivity for an ECG?
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What is the effect on an ECG if the time constant is too low?
What is the effect on an ECG if the time constant is too low?
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AHA specifications state that the input impedance of an ECG should be greater than 0.5MΩ
AHA specifications state that the input impedance of an ECG should be greater than 0.5MΩ
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What is the significance of the Common Mode Rejection Ratio (CMRR)?
What is the significance of the Common Mode Rejection Ratio (CMRR)?
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What is the purpose of the 'Filter on' annotation on an ECG trace?
What is the purpose of the 'Filter on' annotation on an ECG trace?
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What is the AHA-specified frequency response for an ECG?
What is the AHA-specified frequency response for an ECG?
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The AHA states that the CMRR should be at least 1000:1 between 45-65 Hz when imbalanced by 5KΩ.
The AHA states that the CMRR should be at least 1000:1 between 45-65 Hz when imbalanced by 5KΩ.
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An ECG system should have a high linearity to ensure accurate readings.
An ECG system should have a high linearity to ensure accurate readings.
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Explain what a low value for Patient Isolation in an ECG system implies.
Explain what a low value for Patient Isolation in an ECG system implies.
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What are the three recommended steps for ensuring a safe and accurate ECG recording?
What are the three recommended steps for ensuring a safe and accurate ECG recording?
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A sensitivity setting of 20 mm/mV will produce a smaller ECG waveform compared to a setting of 10 mm/mV.
A sensitivity setting of 20 mm/mV will produce a smaller ECG waveform compared to a setting of 10 mm/mV.
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A faster paper speed will make the heart rate appear higher on the ECG trace.
A faster paper speed will make the heart rate appear higher on the ECG trace.
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The AHA guidelines recommend a high frequency response for an ECG
The AHA guidelines recommend a high frequency response for an ECG
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Match the following specifications of an ECG with their effect if not met:
Match the following specifications of an ECG with their effect if not met:
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Study Notes
ECG Instrumentation
- ECG instrumentation uses scientific principles to record the heart's electrical activity.
- Learning outcomes include understanding the principles, technical parameters, and AHA specifications for electrocardiographs.
- Electrocardiograph is an instrument used to record heart's electrical activity.
- Electrocardiogram is the tracing produced by the electrocardiagram.
Correct Terminology
- An electrocardiograph is an instrument for recording the electrical activity of the heart
- An electrocardiogram (ECG) is a tracing produced by an electrocardiograph.
- The ECG tracing shows different waveforms that represent different parts of the heartbeat.
SI Units
- Measured units and their abbreviations are provided for distance, frequency, current, potential difference, resistance, conductance, capacitance, time, weight, and mass.
Scientific Notation
- Scientific notation and associated symbols are provided for prefixes like Tera, Giga, Mega, Kilo, Milli, Micro, Nano, and Pico.
- Examples of using these prefixes on measurements like volts, GHz, megaohms, kilohertz, millivolts, microamps, and nanofarads are also provided.
Biopotential Systems
- Biopotential systems typically have a transducer component, followed by a processor, and then a display.
ECG Measurements
- ECG recordings show measurements of amplitude (voltage) and time.
- Typical components of ECG measuring instruments are a scale, pointer, a current hair spring
Equipment Standards & Specifications
- AHA specifications for various ECG features have been highlighted during the presentation, such as input impedance, common-mode rejection ratio, linearity, time constant, and patient isolation.
Heart Rate
- Heart rate is measured as part of ECG analysis, and it is crucial for understanding the heartbeat regularities.
AHA Specifications
- Equipment, input impedance, common-mode rejection ratio, linearity, time constants, and patient isolation are all part of AHA specifications, standards, and guidelines for medical devices.
Input Impedance
- Input impedance is a crucial parameter for an ECG, representing the resistance to current flow.
- High input impedance is essential so as not to attenuate small electrical signals of the heart's action potentials.
- The AHA recommends input impedance should be greater than 0.5 ΜΩ.
Circuits (Ohm's Law)
- Ohm's Law (V=IR) is applicable to ECG circuits when determining potential difference in series circuits.
Electrodes, Low & High Impedance
- Low impedance electrodes are essential to minimize signal loss across the body
- High impedance components, such as the ECG system, are used to avoid damage from high currents.
Input Impedance (Z)
- AHA guidelines dictate the minimum input impedance that should be higher than 0.5ΜΩ.
- Failure to meet the specification leads to a reduction in the amplitude of the ECG waveform.
- The input impedance should be high. Nothing can be altered.
Common Mode Rejection Ratio (CMRR)
- The Common Mode Rejection Ratio (CMRR) is the ability of an ECG amplifier to suppress common-mode signals in noise.
- Good CMRR results in a clean ECG tracing without noticeable interference.
- AHA guidelines specify a minimum CMRR of 1000:1 between 45-65 Hz when imbalanced by 5KΩ.
- CMRR should be high. Nothing can be altered.
Linearity
- The electrocardiograph should maintain a nearly linear relationship between the input and output.
- An ideal electrocardiograph would have this property within 5% of the chart's width.
- Nothing can be altered.
Time Constant
- Describes the electrocardiograph's ability to process low frequency, slowly changing signals.
- The time constant refers to how quickly the amplitude of change subsides during a measurement.
- The time constant should be more than 3.2 seconds according to the AHA guidelines.
- Nothing can be altered.
Patient Isolation
- The patient isolation of an ECG system refers to the safety measures taken to limit the maximum amount of current passing to the patient.
- AHA guidelines set the maximum acceptable current at less than 10 μA.
- There are various outcomes if the restriction is not respected from slight perception to death.
Operator Dependent
- ECG machine settings can be adjusted by the operator for sensitivity, paper speed, and other parameters
Sensitivity
- Sensitivity is adjustable to alter the ECG trace's amplitude.
- Common adjustable choices are 5mm/mV, 10mm/mV, and 20mm/mV.
- AHA dictates that 1 mV should equal 10mm on the paper. Misdiagnosis might occur from other results.
- Machine settings should be checked prior to use.
ECG Paper Speed
- Paper speed is the rate at which ECG paper moves through the machine during a recording.
- AHA guidelines state that 25mm equals 1 second. Heart rate will be altered if setting is compromised.
- Paper speed affects the displayed timing of the waveform on the trace.
- The operator must use 25 mm per second and document the appropriate settings.
Frequency Response
- The frequency response of the ECG is the range of electrical frequencies over which the machine correctly works.
- According to the AHA, the frequency should be between 0.05 Hz and 150 Hz.
- If the response goes out of range, the ECG waveform will be distorted.
Summary of AHA Standards
- A table summarizes the important AHA standards for ECG parameters, for example, Common Mode Rejection Ratio, Input Impedance, Linearity (5% or less tolerance), Time Constant (more than 3.2 seconds), Patient isolation (less than 10µA), Sensitivity (10mm/mV), Paper Speed (25mm/s), and Frequency Response (0.05 Hz to 150 Hz).
References
- AHA guidelines, IEC60601-1 standards, and SCST paper "12 lead resting ECG consensus" are crucial references.
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Description
This quiz covers the principles and technical parameters of ECG instrumentation, including the definitions of electrocardiographs and electrocardiograms. You'll also learn about SI units and scientific notation relevant to measuring electrical activity of the heart. Test your knowledge on the specifications and waveforms represented in ECG tracings.
