GE Healthcare
Quick Guide
GE EK-Pro
Arrhythmia Algorithm
Multi-lead arrhythmia monitoring
Arrhythmia means any disturbance or irregularity of the cardiac rhythm. Stability of the cardiac rhythm is essential for sufficient pumping function of the heart and adequate cardiac output. Maintaining adequate cardiac output is vital for organ perfusion and survival. Therefore, fast and accurate detection of arrhythmia is critical.
Each ECG lead views the heart at a unique angle. Multi-lead monitoring provides continuous viewing of the heart rhythm from multiple sites. The more leads that are used, in general, the more reliable the information is for arrhythmia analysis.
A multi-lead arrhythmia algorithm uses more than one ECG lead for detection and analysis of cardiac arrhythmias. The performance of a multi-lead algorithm, in general, may exceed that of a single-lead algorithm. In noisy situations, there might be noise present on some leads, while the signal in other leads might be good enough for reliable detection of cardiac rhythm. Sometimes ventricular beats can be more obvious in some of the leads than in others where the changes in morphology are minor. It is also possible that QRS amplitude can be low in one lead and normal in others. Therefore, the sensitivity of the algorithm may increase when more than one lead is used.
The recognition of ventricular beats may be improved by multi-lead monitoring, and the same applies to QRS detection. The decision between normal and ventricular beats may be more reliable when information from more than one lead is available. The GE EK-Pro arrhythmia algorithm uses I, II, III, and the V/VA lead for arrhythmia detection. The American Heart Association (AHA) has recommended that two or preferably three or more leads should be displayed and monitored simultaneously. Exceeding the AHA’s minimum recommendation, the distinctive GE EK-Pro algorithm utilizes four simultaneous leads for analysis.
Window in CARESCAPE modular monitors to select the ECG leads to be analysed.
How are arrhythmias monitored?
The GE EK-Pro algorithm processing can be represented by three major phases: 1) Event Detection and Correlation,
2) Event Measurement and Classification, and 3) Arrhythmia Detection. Continuous correlation, incremental template updating and contextual analysis are processing techniques used by the GE EK-Pro algorithm. Continuous correlation attempts to find the best match between each incoming complex and the set of stored (learned) templates. Incremental template updating allows information from each beat,
which correlates over time, to be reflected in the associated template. Contextual analysis uses information from neighboring QRS complexes along with existing template measurements to make the best possible decision regarding the beat’s origin (e.g., early, wide). Additionally, the GE EK-Pro algorithm also monitors ST changes of up to 12 leads.
For ST monitoring details, please consult the appropriate user manual.
Event Detection and Correlation filters the incoming signal before detecting the incoming events. As the events are detected, incremental template updating is applied on the signal. Here also the noise analysis is done in order to decide whether if any of the incoming channels are too noisy to be analyzed. Each detected QRS complex is compared to previously detected QRS complexes and the templates are updated accordingly, or a new template is created and the beat is added on the beat list.
Event Measurement and Classification task uses the beat list to define the timing, for example, the temporal information of the patient rhythm. The algorithm can classify the beat in question by using the information from the preceding and following beats. A beat is classified as normal, ventricular or artifact and, in combination of the decision of the past beat template, the final label is given and the heart rate is also updated accordingly.
Arrhythmia Detection uses the beat list to get information in run lengths of normal and ventricular beats. Based on this, R-R interval information and heart rate, the algorithm concludes whether there are any arrhythmias present. The criteria for calling an arrhythmia are listed in the table at the end of this document. There is a separate analysis to detect the presence of ventricular fibrillation.
Practical aspects in bedside arrhythmia monitoring
Signal quality
Carefulskinpreparationandtheuseofhigh-qualityelectrodes are key to ensuring a good signal in ECG and especially arrhythmia monitoring. A good signal helps ensure accurate arrhythmia detection and helps decrease the number of false alarms. In case there is an artifact in one of the analyzed leads, the GE EK-Pro algorithm gives a message on noisy ECG and, if the condition continues, the algorithm finally goes into suspend mode. This is communicated by “Arrhyhtmia paused” or “Arrhy suspend” message, depending on the GE monitor in use. Artifacts can be a result of motion or poor skin-electrode contact.
Relearning
When the morphology of the patient’s ECG changes considerably (e.g. due to change of electrodes/electode locations), relearning should be started manually. This can be done in the ECG menu by selecting Relearn QRS.
Patients with pacemakers
Pacemaker detection needs to be activated when patients with pacemakers are monitored. Pacemaker detection
is always on with the E-PSM or E-PRESTN module family. Pacemaker detection needs to be activated when the CARESCAPE™ Patient Data Module or Tram™ is used.
The Advanced ECG tab provides the user with options to adjust the ECG settings. Examples of options include Pacemaker Detection, Relearning QRS, and switching between multi-lead and single lead analysis.
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