Complete AV block
This ECG is taken from a woman who had suffered for several years with intractable intermittent atrial fibrillation. She had tolerated medications poorly, and several attempts at electric cardioversion had resulted in only temporary relief.
This rhythm strip shows third-degree AV block, also called complete heart block or complete AV block. The P waves are from the sinus node, and are regular at a rate of about 120/min. (Sinus tachycardia). This is a good strip for showing your students how to "march out" the P waves to find the ones that are hidden behind QRS complexes or T waves. Knowing that the P waves are regular, it is easy to find the hidden ones.
This ECG was taken from a 90-year-old woman. We have no other history, unfortunately. It is a good example of a sinus rhythm with complete AV block, also called third-degree AV block.
The defining characteristics of this rhythm include: 1) an underlying rhythm that is regular and with a physiological rate. In other words, the P waves are not so fast that they would not be expected to conduct one-to-one. 2) a second rhythm of regular QRS complexes that is unrelated to the P waves.
This patient has an underlying atrial fibrillation with complete heart block and an idioventricular escape rhythm. She was treated successfully with a permanent implanted pacemaker.
This ECG is from an 84-year-old man who experienced dizziness and a fall. He was not injured in the fall. In this ECG, we can clearly see regular P waves at about 110 per minute. We also see wide QRS complexes at about 52 per minute. There is AV dissociation - there are no regular PR intervals, or even progressively-prolonging PR intervals. The atrial and the ventricles are beating to separate rhythms. What is interesting about this rhythm is the origin of the escape rhythm.
This ECG is taken from a patient with an implanted pacemaker who was experiencing near-syncope. She was taken to the hospital by EMS, where the pacemaker was adjusted to obtain ventricular capture. This ECG did not have a Lead II rhythm strip, so the 12-lead ECG is being presented. 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 rhythm strip shows a good example of complete (third-degree) AV block with ventricular escape rhythm. It will be easy for your basic students to "march out" the P waves. They are regular at a rate of about 88/min., and they are either visible, or are "hiding" in the QRS complex. The ventricular rhythm is wide and very slow, and completely dissociated from the sinus rhythm.
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