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ECG _Electrocardiogram_ _part 1

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					ECG (Electrocardiogram) (part 1)




Electrocardiogram (ECG) is a graph created by an electrocardiograph, which records the
heart's electrical activity within a certain time. Its name consists of a number of different
parts: electro, because it relates to electronics, cardio, Greek word for heart, gram, a Greek
root meaning "to write". Analysis of a number of waves and normal vectors of depolarization
and repolarization produce important diagnostic information.

 It is the gold standard for diagnosis of cardiac arrhythmias
 Guiding therapy and risk levels for patients with suspected acute cardiac infarction bibs
 Helping find electrolyte disturbances (eg hyperkalemia or hypokalemia)
 Enables discovery of conduction abnormalities (eg right bundle branch block and left)
 Used as a filter tool ischemic heart disease during cardiac stress test
 Sometimes it's not useful for detecting heart disease (eg pulmonary embolism or
hypothermia)

Electrocardiogram does not directly assess cardiac contractility. However, the ECG may
provide a thorough indication of the ups and downs of a contractility.


Paper ECG recorder




A typical electrocardiograph runs at a paper speed of 25 mm / s, although speeds above are
occasionally used. Each small block of ECG paper is 1 mm ². With a speed of 25 mm / s, 1
small box of ECG paper translates into 0.04 s (40 ms). 5 small boxes up a large box, which is
equal to 0.20 s (200 ms). Therefore, there are 5 large blocks per second. A diagnostic quality
12 lead ECG is calibrated at 10 mm / mV, so 1 mm translates into 0.1 mV. Signal
"calibration" should be included in every record. Standard signal of 1 mV must move the
stylus vertically 1 cm, ie, 2 large squares on ECG paper.
Filter Selection
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
high-pass filter because signals above the threshold to pass) set at either 0.5 Hz or 1 Hz and
high frequency filter (also called low-pass filter because signals below the threshold are
allowed to pass ) is set at 40 Hz. This limits artifact for routine cardiac rhythm monitoring.
High-pass filter helps reduce wandering baseline and low pass filter helps reduce power line
noise 50 or 60 Hz (power line network frequency differs between 50 and 60 Hz in some
countries). In diagnostic mode, the high pass filter set at 0.05 Hz, which allows accurate ST
segments recorded. Low pass filter set at 40, 100, or 150 Hz. As a result, the monitor mode
ECG display is more filtered than diagnostic mode, because its bandpass is narrower.

				
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Description: ECG _Electrocardiogram_ _part 1