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QT Interval Variability
QT interval variability (QTV) refers to the physiological phenomenon of beat-to-beat fluctuations in QT interval of electrocardiograms. Increased QTV appears to be a marker of arrhythmic and cardiovascular death; it may also play a role for noninvasive assessment of sympathetic nervous system activity. Other terms used include: "QT variability", "beat-to-beat variability of ventricular repolarization (BRV)" QT interval measurement Under normal resting conditions, beat-to-beat changes in QT interval are very small with a standard deviation typically below 5 ms. Digital high resolution ECG sampled at 300 Hz or higher and dedicated computer algorithms are required for QTV assessment. Template-based algorithms that use parts of, or the entire ECG waveform usually deliver good results; template stretching or warping techniques perform comparably well in the presence of noise. QTV Analysis A number of metrics have been proposed for QTV quantification. The QT variability index (QTVi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QT Interval
The QT interval is a measurement made on an electrocardiogram used to assess some of the electrical properties of the heart. It is calculated as the time from the start of the Q wave to the end of the T wave, and approximates to the time taken from when the cardiac ventricles start to contract to when they finish relaxing. An abnormally long or abnormally short QT interval is associated with an increased risk of developing abnormal heart rhythms and sudden cardiac death. Abnormalities in the QT interval can be caused by genetic conditions such as long QT syndrome, by certain medications such as sotalol or pitolisant, by disturbances in the concentrations of certain salts within the blood such as hypokalaemia, or by hormonal imbalances such as hypothyroidism. Measurement The QT interval is most commonly measured in lead II for evaluation of serial ECGs, with leads I and V5 being comparable alternatives to lead II. Leads III, aVL and V1 are generally avoided for measuremen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrocardiograms
Electrocardiography is the process of producing an electrocardiogram (ECG or EKG), a recording of the heart's electrical activity. It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the heart using electrodes placed on the skin. These electrodes detect the small electrical changes that are a consequence of cardiac muscle depolarization followed by repolarization during each cardiac cycle (heartbeat). Changes in the normal ECG pattern occur in numerous cardiac abnormalities, including cardiac rhythm disturbances (such as atrial fibrillation and ventricular tachycardia), inadequate coronary artery blood flow (such as myocardial ischemia and myocardial infarction), and electrolyte disturbances (such as hypokalemia and hyperkalemia). Traditionally, "ECG" usually means a 12-lead ECG taken while lying down as discussed below. However, other devices can record the electrical activity of the heart such as a Holter monitor but also s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2DSW Concept Schematic (Two-dimensional Signal Warping)
DSW may refer to: * DSW, the SAME code for a Dust Storm Warning * Deep South Wrestling, a pro wrestling promotion that was a developmental territory of World Wrestling Entertainment * '' The Doon School Weekly'', a student newspaper produced by the boys of The Doon School Personnel * Diving salvage warfare specialist, a United States Navy enlisted warfare designator * Doctor of Social Work Organisations * DSW (“Designer Shoe Warehouse”), big-box footwear retailer, headquartered in Columbus, Ohio * German School Washington, D.C. (DSW) (german: Deutsche Schule Washington, D.C.) * German Foundation for World Population (german: Deutsche Stiftung Weltbevölkerung), an international nongovernmental organization based in Germany Computing * Day–Stout–Warren algorithm for balancing binary search trees * dsw (command) dsw was a Unix command which enabled deletion of files with non-typeable characters. It was replaced by the same functionality implemented in rm, namely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart Rate Variability
Heart rate variability (HRV) is the physiological phenomenon of variation in the time interval between heartbeats. It is measured by the variation in the beat-to-beat interval. Other terms used include: "cycle length variability", "R–R variability" (where R is a point corresponding to the peak of the QRS complex of the ECG wave; and RR is the interval between successive Rs), and "heart period variability". Methods used to detect beats include: ECG, blood pressure, Ballistocardiography, ballistocardiograms, and the pulse wave signal derived from a photoplethysmograph (PPG). ECG is considered the gold standard for HRV measurement because it provides a direct reflection of cardiac electric activity. Clinical significance Reduced HRV has been shown to be a predictor of mortality after myocardial infarction although others have shown that the information in HRV relevant to acute myocardial infarction survival is fully contained in the mean heart rate. A range of other outcomes an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Example Traces Of Heart Rate And QT Interval Variability In A Normal Heart And After Myocardial Infraction
Example may refer to: * '' exempli gratia'' (e.g.), usually read out in English as "for example" * .example, reserved as a domain name that may not be installed as a top-level domain of the Internet ** example.com, example.net, example.org, example.edu, second-level domain names reserved for use in documentation as examples * HMS ''Example'' (P165), an Archer-class patrol and training vessel of the Royal Navy Arts * '' The Example'', a 1634 play by James Shirley * ''The Example'' (comics), a 2009 graphic novel by Tom Taylor and Colin Wilson * Example (musician) Elliot John Gleave (born 20 June 1982), better known by his stage name Example, is an English musician, singer, songwriter, rapper and record producer. His name arose due to his initials being E.G., which is an abbreviation of the Latin phrase ..., the British dance musician Elliot John Gleave (born 1982) * ''Example'' (album), a 1995 album by American rock band For Squirrels See also * * Exemplar (disambi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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