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This strip was obtained from a woman who presented to her doctor’s office with hypertension. While there is some artifact in the baseline, it is possible to determine the presence of P waves, thanks in part to having two leads to assess. We have provided an unmarked version of the strip for you to use, and also a marked version for the sake of this discussion.
This ECG was recorded from a 75-year-old man with substernal chest pain and diaphoresis. It shows a pretty classic picture of acute inferior wall M.I. The second ECG is a repeat tracing with the V4 wire moved to the V4 Right position, and it is positive for right ventricular M.I. The patient was found to have a 100% occlusion of the right coronary artery, which was opened and stented in the cath lab.
This ECG is from an 80-year-old woman who had an acute inferior wall M.I. with a second-degree AV block.
Some people incorrectly call ALL second-degree AV blocks that are conducting 2:1 "Type II". This is incorrect, as Mobitz Type I can also conduct with a 2:1 ratio. The progressive prolongation of the PR interval will not be seen with a 2:1 conduction ratio, because there are not two PR intervals in a row.
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.
Today's basic rhythm strip illustrates second-degree AV block, Type II. Even though there is fine baseline artifact present, it is easy to measure the P-to-P interval, and your students will be able to see that every third P wave falls in the T wave. The PR intervals are constant and the atrial rate is about 110/min. The ventricular rate results from a 3:1 conduction ratio, and is less than 30/min.
This 67 year old man is noted to have a slightly irregular pulse. At the beginning of this ECG, he appears to be in NSR with a first-degree AV block. Twice, P waves are non-conducted. Careful measurement of the P to P interval shows that it is regular, there are no PACs noted. The PR interval changes very subtly by lengthening just before the non-conducted P waves. A hint when non-conducted P waves are noted, first check for non-conducted PACs. If the sinus rhythm is regular, check the PR interval before the non-conducted beat, and the PR interv
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