Fluke Biomedical ProSim 6 - Manual (Page 96)

ProSim™ 6/8
Users Manual
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another kind of artifact (also called noise) that can be picked up by an ECG device. These
sources can cause minute electric currents through capacitive coupling or resistive
contacts. On an ECG readout, such electrical artifacts can cause a serious safety
condition. Even a relatively tiny current of 60 hertz (Hz) can be fatal. Therefore,
whenever line frequency in an electrocardiogram is noted, the cause of the signal should
be determined at once
Asynchronous
Signals sent to a computer at irregular intervals. Data is transmitted at irregular intervals
by preceding each character with a start bit and following it with a stop bit.
Asynchronous transmission allows a character to be sent at random after the preceding
character has been sent, without regard to any timing device.
Asystole (Cardiac Standstill)
No ECG activity whatsoever. Ventricular asystole is a critical condition characterized by
the absence of a heartbeat either in the ventricles or in the entire heart. This condition,
also referred to as cardiac standstill, is usually accompanied by loss of consciousness,
apnea, and—if not treated immediately—death.
Atrial Fibrillation
A rapid, irregular atrial signal, coarse or fine, with no real P waves; an
irregularventricular rate. Coarse and fine atrial fibrillation occurs when the electrical
signals in the atria are chaotic, and multiple, ectopic pacemakers are firing erratically.
Some impulses may conduct through to the AV node to stimulate the ventricles, causing a
quite-irregular and often-rapid ventricular rate. On the ECG there is an absence of P
waves, with an irregular R-R interval. Atrial-fibrillation waveforms are irregularly shaped
and usually rounded. The amplitude of the atrial signal is higher for coarse, and lower for
fine, fibrillation.
Atrial Flutter
A repeating sequence of large, irregular P waves at 300 BPM; an irregular ventricular
response. Atrial flutter occurs when a single, ectopic, atrial pacemaker that is non-SA
(usually low, near the AV node) fires repeatedly and (usually) regularly, producing large,
pointed P waves at an approximate rate of 400 BPM (between 240 and 480 BPM). Not all
of the atrial impulses conduct through to the ventricles. On the ECG readout the
waveform generally exhibits a “saw tooth” appearance. This type of arrhythmia can
reduce cardiac output by as much as 25 %, due in many cases to the lack of an atrial
“kick” and the accompanying failure of the ventricles to fill completely with blood prior
to ventricle contraction.
Atrial Tachycardia (AT)
Normal rhythm at a faster-than-normal rate of 160 BPM.
Atrial tachycardia occurs when an ectopic, atrial pacemaker (non-SA) fires repeatedly at
a rate between 150 and 250 BPM. AT may cause cardiac output to drop significantly (in
some cases by as much as 25 %), due to the inability of the ventricles to fill completely
during the typically short diastole. This condition may result from an atrioventricular
blockage or digitalis toxicity.
Atrium
(1) One of the two upper chambers of the heart. (2) Any chamber allowing entrance to
another structure or organ.
AV Junction
A junction consisting of the AV node and the bundle of His. Conducts the electrical
impulse sent from the SA node from the atria into the ventricles.