ECG Interpretation Review #44 (AFib - Flutter - Artifact - Parkinson - Tremor)

The lead II rhythm strip shown in Figure 1 was observed on telemetry. 

• Is the patient in atrial flutter?

Figure 1 – Lead II rhythm strip observed on telemetry. Is this atrial flutter?

INTERPRETATION: At first glance — one might be tempted to say atrial flutter was present. However, more careful inspection suggests that the baseline deflections do not represent atrial activity at all. In adults — atrial activity with atrial flutter is almost always regular at a rate of between 250-to-350/minute. Typically it manifests a “sawtooth” pattern in lead II. The deflections in question for this example are more geometric in configuration (ie, vertical) – they are irregular — and they far exceed the expected rate range for atrial flutter in an adult because they occur at a rate of between 400-to-500/minute. A look at the patient confirmed that these small amplitude vertical deflections were the result of tremor artifact. 

• It is difficult to determine what the true rhythm in Figure 1 really is. The rate (95-to-100/minute), apparently normal QRS duration, and near regularity of the rhythm suggest a sinus etiology. 
• That said – from this tracing alone, one could not rule out the possibility of either accelerated junctional rhythm (since no definite P waves are seen) — or atrial fibrillation (since there is a slight irregularity to the rhythm). 
• IF there was a need to know clinically — one could either attempt to repeat the rhythm strip or obtain a 12-lead ECG in the hope that other leads might be less distorted by artifact. 

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About ARTIFACT: Although admittedly devious on our part to show artifact in our Blog – we intentionally do so because: 

• Artifact is an extremely common finding in the real world. 
• Patients have been medicated, and even cardioverted or defibrillated when artifact has not been recognized or has been misinterpreted. 
• Familiarity with the common types of artifact encountered, and attention to a few basic points usually makes recognition easy. 
• Failure to actively include the possibility of artifact into your differential greatly increases the chance of it being overlooked. 

BOTTOM LINE: Suspect artifact whenever physical or electrocardiographic findings do not “fit” with the arrhythmia diagnosis being contemplated. Thus, a chaotic pattern without any organized activity cannot be ventricular fibrillation if the patient remains awake and alert. Similarly, deflections occurring at a rate of 400-to-500 times/minute (as shown in Figure 1) are far too rapid to be atrial flutter — especially in view of the morphology, irregularity, and clinical history (of tremor) in this case. 

• PEARL: Parkinsonian tremor typically occurs at a speed of 4-to-6 cycles per second. This is close to the speed of atrial flutter — so the two entities may easily be confused. KEY distinguishing features of Parkinsonian tremor are: i) irregularity of tremor deflections; ii) more geometric appearance (up-and-down) than “sawtooth”; and, iii) the patient will manifest tremor … 

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