Arrhythmia Algorithm ECG – Arrhythmia
9 - 22 V Series Operating Instructions
9.6.2 Heart Rate Meter
Heart Rate is computed using the 16 most recent R-R intervals for heart rates above 48 beats per
minute. If the heart rate calculated using the last 4 beats is less than 48 beats per minute, then this
rate is used. All detected beats are used to compute the heart rate. A separate ventricular rate is used
in the algorithm to determine rhythms like ventricular tachycardia and ventricular run.
9.6.3 Filtering Pacer Signals
In order to prevent pacer pulses from being mistaken for QRS complexes, they are removed from the
ECG data that is sent to the arrhythmia algorithm for analysis. Pacer pulses are shown on the V 12/V
21 as exaggerated vertical lines.
9.6.4 ECG Amplitude
The minimum threshold for QRS detection algorithm can be adjusted to avoid detecting noise spikes
or P-waves as valid beats. Refer to "Configuring the QRS Threshold" on page 12-4 for additional
information. Changing the display gain on the monitor does not affect the amplitude of signal that is
used by the algorithm for beat detection. For optimal performance, the leads selected for monitoring
should have amplitudes of 0.5 to 1 mV or more.
9.6.5 Learning
The process of learning is used to establish a dominant beat template for a patient. The learning
period is dependent on the heart rate and the dominant pattern. Learning should not be initiated
during a primarily ventricular rhythm because an ectopic beat may be established as normal.
A learn should be initiated when beats are not being properly detected, or when they are being
erroneously classified. However, if a signal is not strong enough, or lead data is extremely noisy, better
signal quality must be established before a learn can be effective.
9.6.6 Beat Detection and Typing
The following table describes the leads that are used to measure beat detection and beat typing.
Once a beat has been detected, the search for the next beat begins after a refractory period to avoid
detecting T- waves as valid QRS complexes. For all patient sizes, the minimum QRS amplitude that
can be detected is between 0.15 and 0.45 mV depending on the width of the QRS complexes.
Beat typing aligns and compares each new heart beat to reference templates that were previously
stored in the system. A beat typing algorithm classifies the beats.
• If an incoming beat matches a template that has already been classified, it is given the same label
as the template. The template parameters are updated with the features from this new beat.
The real time ECG analysis library incorporates ventricular ectopic beat detection as a part of
arrhythmia analysis.
DESCRIPTION 3-WIRE LEAD SET 5, 10-WIRE LEAD SETS*
Leads used for Beat Detection Determined by viewed lead II and V
Leads used for Beat Typing Determined by viewed lead II, V, and I
Leads used for V-Fib Detection Determined by viewed lead II and V
* Indicates that these leads are user configurable. Refer to "ECG Analysis Leads" on page 9-23.
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