The mA (energy setting) was adjusted in the Emergency Dept., and the pacemaker did not require repositioning. The second and fourth P waves did not stimulate a pacer spike because of their proximity to the T wave of the junctional beat. They are not followed by a paced QRS complex, however.
The pacer spikes, for the most part, track the P waves, which is how this pacemaker is programmed. This explains why the patient had a pacemaker implanted. Because both atrial and ventricular rhythms are regular, but not associated with each other, an interpretation of complete heart block (third-degree AV block) can be made. Because the rate is near or just under 40 bpm, and the QRS complexes are narrow, this represents a slow junctional rhythm. The QRS complexes are also regular, but they are dissociated from the P waves. The underlying rhythm is sinus, with nearly regular P waves occuring at a rate of about 72 beats per minute. Because we can see 12 leads, or viewpoints, the morphology of the P waves and QRS complexes changes each time the machine switches to a new lead. The P waves have been marked with a "P", pacemaker spikes marked with an arrow, and the QRS complexes marked with a "J" because they are junctional. This ECG did not have a Lead II rhythm strip, so the 12-lead ECG is being presented. She was taken to the hospital by EMS, where the pacemaker was adjusted to obtain ventricular capture. This ECG is taken from a patient with an implanted pacemaker who was experiencing near-syncope. Read more about Transcutaneous Pacemaker: Failure to Capture and False QRS Artifact.The patient’s clinical signs (skin perfusion, blood pressure, mentation) should be used to determine whether the rate is adequate. This is a good ECG to illustrate the artifact that is possible with transcutaneous pacing, and remind your students not to assume the patient is being paced. It is likely that the rate and/or the MA, or milliamps, need to be increased to achieve pacing with capture. The pacemaker is sensing the patient’s native beats, but not pacing. Apparently, the pacing is stopped, then the pacer is set to “demand” mode. There is failure to sense AND failure to capture. It does not sense the normal QRS that occurs after the second pacing stimulus. The rate is very slow – in the 30’s.Īt the beginning of the strip, there are four pacing stimuli, with artifact. In this strip, the underlying sinus bradycardia is uninterrupted across the strip. Also, the pacing of the chest wall muscles can be misinterpreted as a pulse. This artifact is sometimes confused for a QRS complex. When using a transcutaneous pacemaker, it is important to remember that the pacing stimulus can cause an artifact on the ECG.
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