- T wave alternans
T wave alternans TWA is a periodic beat to beat variation in the amplitude or shape of the T wave in an electrocardiogram ECG or EKG . Image SinusRhythmLabels.svg 300px right thumb T wave of ECG TWA was first described in 1908. At that time, only large variations macroscopic TWA could be detected. Those large TWAs were associated with increased susceptibility to lethal ventricular tachycardia s. Most modern references to TWA refer to microvolt T wave alternans MTWA , a non invasive heart test that can identify patients who are at increased risk of sudden cardiac death ref Chow T, Saghir S, Bartone C, Goebel M, Schneider J, Booth T, Chan PS. Usefulness of microvolt T wave alternans on predicting outcome in patients with ischemic cardiomyopathy with and without defibrillators.Am J Cardiol. 2007 Aug 15 100 4 598 604. Epub 2007 Jun 28. ref ref Bloomfield DM, Bigger JT, Steinman RC, Namerow PB, Parides MK, Curtis AB, Kaufman ES, Davidenko JM, Shinn TS, Fontaine JM. Microvolt T wave alternans and the risk of death or sustained ventricular arrhythmias in patients with left ventricular dysfunction. J Am Coll Cardiol. 2006 January 17 47 2 456 63. Epub 2005 December 15. ref . It is most often used in patients who have had myocardial infarction s heart attacks or other heart damage to see if they are at high risk of developing a potentially lethal cardiac arrhythmia . Those who are found to be at high risk would therefore benefit from the placement of a defibrillator device which can stop an arrhythmia and save the patient s life. The TWA test uses an electrocardiogram ECG measurement of the heart s electrical conduction. The test looks for the presence of repolarization alternans T wave alternans , which is variation in the vector geometric vector and amplitude of the T wave component of the EKG. The amount of variation is small, on the order of microvolts, so sensitive digital signal processing techniques are required to detect TWA. Microvolt T wave Alternans MTWA Microvolt ... more details
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- Noise (electronics)
, thermal noise Voltage in microvolts, conversion to noise level in dBu and dBV and vice versa FS1037C ... more details
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- Contingent negative variation
stimulus will be. The maximum amplitude is usually around 20 microvolts. ref name Tecce Topography ... more details
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- N400 (neuroscience)
. Its amplitude can range from 5 to 5 volt microvolts . However, it is important to note that in studies ... more details
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- Altran Foundation for Innovation
, in work on data acquisition electrical signals of only a few microvolts and has allowed evaluating ... more details
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- Valve RF amplifier
noise is specified see e.g., the Valvo, Telefunken or Philips data sheets as 2 microvolts integrated ... more details
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- Thermocouple
, and is between 1 and 70 microvolts per degree Celsius V C for standard metal combinations ... more details
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- Auditory brainstem response
. ABR is measured in microvolts millionths of a volt and the ASSR is measured in nanovolts billionths ... more details
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- University Radio Essex
at the campus boundary to 100 microvolts per metre, and the presence of a strong signal on an adjacent ... more details
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- Sense
27, 2011, page 12. ref These electroreceptors can detect electric fields as weak as 4.6 microvolts ... more details
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- Decibel
when spec sheets may show the voltage & power level e.g. 120 dBm 0.224 microvolts. dB V m or dBuV m ... more details
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- Comparison of analog and digital recording
of just 7.629 microvolts. For an analog recorder, this is equivalent to a 15.3 Parts ... more details
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- Schumann resonances
of the instruments is 3 100 Hz. The Schumann resonance electric field amplitude 300 microvolts ... more details
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- Valve audio amplifier ? technical
, Telefunken or Philips data sheets as 2 microvolts integrated over a frequency range of approximately ... more details
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- P3b
is generally relatively large 10 20 microvolts ref Polich, J. & Kok, A. 1995 . Cognitive and biological ... more details
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- Antenna (radio)
30 microvolts root mean square rms at 75 ohms . Since the receiving antenna is not equally sensitive ... more details
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