How to differentiate between Ventricular Fibrillation (VFib) and electrocardiogram (ECG) artifact?

From the Guidelines

To differentiate between ventricular fibrillation (VFib) and artifact on an ECG, focus on the presence of chaotic, irregular waveforms and the absence of discernible QRS complexes, P waves, or T waves, as well as the clinical status of the patient. When evaluating an ECG for VFib or artifact, it's crucial to consider the characteristics of the waveform and the patient's clinical presentation. VFib typically shows chaotic, irregular waveforms without discernible QRS complexes, P waves, or T waves, and maintains this pattern consistently across multiple leads 1. In contrast, artifact often appears in only some leads while others show normal cardiac activity. Artifact frequently correlates with patient movement, loose electrodes, or electrical interference, and may show an underlying regular rhythm visible between artifact segments.

Key characteristics to look for in differentiating VFib from artifact include:

• The presence of chaotic, irregular waveforms in VFib, versus more regular or rhythmic patterns in artifact
• The absence of discernible QRS complexes, P waves, or T waves in VFib
• The clinical status of the patient, with VFib patients typically being pulseless and unresponsive, while patients with artifact remain hemodynamically stable
• The presence of artifact in only some leads, while others show normal cardiac activity
• Correlation of artifact with patient movement, loose electrodes, or electrical interference. As noted in the guidelines for the interpretation of the neonatal electrocardiogram, artifacts are common and can be caused by various factors, including limb lead reversal, incorrect chest lead positioning, electrical interference, and patient movement 1. However, the main clue in determining the presence of an artifact is to evaluate whether it affects the intrinsic rhythm and if it is timed such that it could be a true depolarization. A signal within 80 ms from a true QRS complex could not occur from an electrophysiologic point of view 1.

When in doubt, especially in an unstable patient, it is recommended to treat as VFib until proven otherwise, as delayed defibrillation can be fatal. Quickly assessing the patient clinically, checking lead connections, and considering obtaining a 12-lead ECG or using another monitoring method can help confirm the diagnosis. Remember that artifact may show impossibly rapid oscillations (>600/min) or perfect regularity that doesn't match biological patterns.

From the Research

Distinguishing VFIB from Artifact on ECG

To differentiate between ventricular fibrillation (VFIB) and artifact on an electrocardiogram (ECG), it's essential to analyze the ECG waveform and understand the characteristics of VFIB.

• VFIB is a life-threatening arrhythmia characterized by rapid, erratic electrical activity in the ventricles, resulting in a disorganized ECG waveform 2.
• Artifacts, on the other hand, are external interferences that can mimic VFIB on an ECG, but they do not originate from the heart's electrical activity.

ECG Characteristics of VFIB

VFIB is typically identified by a disorganized, chaotic ECG waveform with no discernible P waves, QRS complexes, or T waves 2.

• The ECG waveform may appear as a zigzag or sinusoidal pattern, indicating the erratic electrical activity in the ventricles.
• The amplitude and frequency of the waveform can vary, making it challenging to distinguish from artifacts.

Distinguishing Features

To differentiate VFIB from artifacts, look for the following features:

• Duration and consistency: VFIB is typically a sustained arrhythmia, whereas artifacts are often transient and intermittent 3.
• Morphology: VFIB has a characteristic disorganized waveform, whereas artifacts may have a more uniform or periodic pattern.
• Clinical context: Consider the patient's clinical history, symptoms, and physical examination findings to determine the likelihood of VFIB versus artifact.

Advanced ECG Analysis Techniques

Advanced ECG analysis techniques, such as complete ensemble empirical mode decomposition, can help improve the accuracy of QRS complex and P wave detection, which can aid in distinguishing VFIB from artifacts 3.

• These techniques can reconstruct the ECG signal and eliminate noise, allowing for more accurate identification of VFIB and other arrhythmias.
• Understanding the normal activation of the ventricles and the QRS complex can also help in identifying abnormal waveforms, such as those seen in VFIB 4.