This strip offers several good teaching opportunities. If it were a 12-lead ECG, no doubt it would be a bonanza! First, there is sinus tachycardia at a rate of about 138 per minute. The P waves are all alike and regular. The T waves are tall and narrow, with a sharp peak. This is often a transient sign of hyperkalemia, and should be investigated with serum electrolyte tests and with a 12-lead ECG. In addition, the baseline shows a wandering type of artifact.
This ECG is being offered as a teaching aid, to show how artifact can affect our ability to interpret an ECG, and to encourage our students to be meticulous in obtaining a good-quality tracing whenever possible. If there are insurmountable obstacles preventing a technically good tracing, the circumstances should be written on the ECG. Such obstacles could be: seizures, tremors, vigorous resuscitation efforts underway, or patient not cooperating.
When using a transcutaneous pacemaker, it is important to remember that the pacing stimulus can cause an artifact on the ECG. This artifact is sometimes confused for a QRS complex. Also, the pacing of the chest wall muscles can be misinterpreted as
This patient was diagnosed by the rescue crew as having atrial fibrillation, based on the fact that they thought the rhythm was irregular, and they could not see P waves. They also noted a wavy baseline, and considered it to be fibrillatory waves. In reality, the underlying rhythm is regular, with some PACs (regularly irregular).
This ECG offers several teaching opportunities. First, it is an example of left bundle branch block (LBBB). It was obtained from a 53-year-old man who was undergoing a cardiac cath for chest pain. Unfortunately, we do not have access to his past medical history or the results of his cath. The ECG criteria for a diagnosis of LBBB are: 1) wide QRS complex; 2) supraventricular rhythm; 3) negative QRS in V1 and positive QRS in V6 and Lead I. This ECG shows normal sinus rhythm at a rate of 88 bpm and a wide QRS at 158 ms (.158 seconds).
This ECG is taken from a 66-year-old man who presented to the Emergency Dept. with a complaint of chest pain. The ECG shows clear signs of acute inferior wall MI: ST segment elevation in Leads II, III, and aVF and reciprocal ST depression in Leads I and aVL. In addition, there are reciprocal ST depressions in Leads V1, V2, and V3. These indicate that the MI extends up the inferior wall into the area called by most clinicians the posterior wall.
This rhythm strip shows normal sinus rhythm, slightly on the fast side of normal at 95 bpm. The baseline undulates up and down with the movements of the patient's chest as she breathes. One way to correct this problem on a monitor strip is to move the limb electrodes away from the chest and onto the limbs.
If you are an ECG instructor, it is important that you address the subject of artifact on the ECG. Artifact has many causes, and it is important eliminate it whenever possible. We should strive for the "cleanest" ECG possible. As you can see in this example, the presence of artifact has caused the machine's computer rhythm interpretation to be incorrect. The noisy baseline has caused the computer to call this rhythm "atrial fibrillation", but we clearly see P waves in all leads, especially in Lead II.
Here is a good example of 60-cycle interference artifact on a sinus rhythm strip. The artifact is caused by electrical interference from a nearby electrical appliance. Modern monitors are able to filter interference out, but it is still occasionally seen. Even though we can still discern P waves in this strip, and we can see that the rhythm is irregular, possibly sinus arrhythmia, the artifact prevents us from accurately evaluating the strip. Every effort should be made to identify the offending device.
All our content is FREE & COPYRIGHT FREE for non-commercial use
Please be courteous and leave any watermark or author attribution on content you reproduce.