Passport V Operating Instructions 0070- 0-0704-02 4 - 23
ECG Monitoring Arrhythmia Algorithm
4.6 Arrhythmia Algorithm
The Passport V uses an arrhythmia algorithm to monitor ECG waveform data. The
algorithm creates ECG waveform templates based on a patient’s normal ECG data and uses
them to analyze newly received data. The algorithm verifies that data is free from noise and
artifact, and that it does not deviate from the patient’s normal ECG rhythms.
A normal ECG waveform typically includes consistent spacing between R waves, a sharp
and well defined QRS complex, and an ECG baseline that is free of noise and artifact.
FIGURE 4-25 Sample Waveform
4.6.1 Noise and Artifact
The presence of noise or artifact in an ECG waveform makes the accurate detection and
classification of heartbeats difficult. To best optimize performance, all leads should be free of
noise.
Some of the causes of ECG noise include poor skin preparation, improperly attached
electrodes, dried electrode gel, defective lead wires, and patient movement. The algorithm
uses several techniques to differentiate a patient’s QRS complexes from noise sources.
If noise levels are too high for a particular lead, a message is posted, and the data is
dropped from analysis until the signal quality is re-established.
If noise levels are too high, the following will occur until the signal quality is re-established:
• Beat detection is suspended
• All rhythm calls are suspended
•An ECG Noise message is displayed
4.6.2 Heart Rate Average
The heart rate average 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.
ST Point
J Point
ST deviation
(Depression or Elevation)
ISO Point
40 to 80 msec
ST Segment
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