Microvolt T-wave alternans and the risk of death or sustained ventricular arrhythmias in patients with left ventricular dysfunction.
Raw
microvolt ([micro]V) potentials were collected using WinEEG (2.93.59) and subsequently converted to SPD ([mu][V.sup.2] x [Hz.sup.-1]) within delta (1.5 Hz-4Hz), theta (4 Hz - 7.5 Hz), alpha (7.5 Hz - 14 Hz), beta1 (14 Hz - 20 Hz), beta2 (20 Hz - 30 Hz), and gamma (30 Hz - 40 Hz) bands.
A variety of aquatic vertebrates, including teleost and non-teleost fish, amphibians, and monotreme mammals, are sensitive to low-frequency electric signals with thresholds of low nanovolts per centimeter to high
microvolts per centimeter, have specialized detectors for these signals, and use electroreception to locate food or orient in their environment (1-9).
Methods used for the TWA measurements allow detecting the periodic changes of the consecutive T-waves amplitude at
microvolt level.
An equivalent amplitude limit on contemporary equipment would be closer to the 2 to 10
microvolt range.
Medicare has ruled that
microvolt T-wave alternans testing should be covered nationally, calling it an accurate screen for sudden cardiac death.
Bloomfield et al., "
Microvolt T-Wave Alternans and the Risk of Death or Sustained Ventricular Arrhythmias in Patients with Left Ventricular Dysfunction," Journal of the American College of Cardiology 47 (2006): 456-63.
"In multiple clinical studies, the
microvolt T-wave alternans testing has been shown to identify accurately both the high- and low-risk patients," explains Dr.
(NASDAQ-CAMH), Bedford, Mass, has announced that clinical results, presented at the annual meeting of the American Heart Association demonstrate that
Microvolt T-Wave Alternans (MTWA) testing can help determine which MADIT II type patients (prior myocardial infarction and left ventricular ejection fraction of 30% or less) should receive an implantable cardioverter defibrillator (ICD).
The samples were allowed to equilibrate in the chamber for 3 h at 25 [degrees] C, then measured with a Wescor model HR-33T dewpoint
microvolt meter.
The value of the emf of the unknown cell, in terms of the value assumed for the reference cell, is then written down as the number appearing in the "unknown cell" window supplemented by the reading of indicator B in
microvolts. A figure for tenths of a
microvolt may be had by estimating tenths of a division in the deflection of indicator B.