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.
Second-degree AV Block
This ECG was obtained from an 84-year-old woman who was scheduled for surgery. When the anesthesiologist did this ECG, the surgery was cancelled. It is a very good example of fascicular-level blocks.
This strip shows a second-degree AV block. During most of the strip, 2:1 conduction is present. At the beginning, however, two consecutive p waves are conducted, revealing progressive prolongation of the PR interval. This usually represents a Type I , or nodal, block: progressive refractoriness of the AV node. However, the wide QRS ( possibly left bundle branch block), and the fact that the non-conducted p waves are "out in the open" where they should have conducted, points to Type II - an intermi
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 interesting ECG is a great one for your more advanced students who are ready to discuss the anatomical and physiological differences between the AV blocks, as opposed to just measuring PR intervals.
This ECG is a follow-up to last week's ECG of the WEEK, which presented an AVB that was mostly conducted 2:1, and proved to be a "Type II" block when it conducted 3:2 with consistent PR intervals at the end. We often just use the term, "2:1 AVB", rather than try to discern the Mobitz type, realizing that the most important feature of a 2:1 block may be that it automatically cuts the heartrate in half.
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
This ECG was taken from an 87-year-old black man and was diagnosed by the reviewing cardiologist as "complete AV block".
Is that really the interpretation or is it something else?
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.