hi i am a cardiac tech student and i have a problem figuring out this question so i would really appreciate it if someone could help me with it , here it is :]
Why would you acquire a 12 lead ECG with precordial leads run on half sensitivity?
If you can't answer the question , please maybe try to explain to me what the question is really asking for.
Oct 9, '12
see if this has the information you need. The summary google has seems to have leaned toward that.
Oct 9, '12
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I am not a wiki fan but I found this interesting......
File:Wiggers Diagram.svg - Wikipedia, the free encyclopedia
Modern ECG monitors offer multiple filters for signal processing. The most common settings are monitor mode and diagnostic mode. In monitor mode, the low-frequency filter (also called the high-pass filter
because signals above the threshold are allowed to pass) is set at either 0.5 Hz or 1 Hz and the high-frequency filter (also called the low-pass filter
because signals below the threshold are allowed to pass) is set at 40 Hz. This limits artifacts for routine cardiac rhythm monitoring. The high-pass filter helps reduce wandering baseline and the low-pass filter helps reduce 50- or 60-Hz power line noise (the power line network frequency
differs between 50 and 60 Hz in different countries). In diagnostic mode, the high-pass filter is set at 0.05 Hz, which allows accurate ST segments to be recorded. The low-pass filter is set to 40, 100, or 150 Hz. Consequently, the monitor mode ECG display is more filtered than diagnostic mode, because its passband is narrower.
So.......my guess would be diagnostic for axis deviation etc. The relevance of this could be in determining whether an abnormality on the ECG is likely to represent true disease or a spurious finding.
I have never been asked to do this........I am anxious to hear the responses.
Oct 9, '12
The thing that came to mind is that half sensitivity refers to 5 mm/1 mV instead of the standard 10 mm/1 mV. You'd change this value in the light of left ventricular hypertrophy or conduction abnormalities that cross into your other leads obscuring the view of those leads. This is generally most prominent in the precordial leads. If I translate roughly from Dutch we'd call it "half calibration" or "half gain".
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