Title | Description | Subject | Collection | ||
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1 | 1st degree AV block | The normal PR interval is 0.12 - 0.20 sec, or 120 -to- 200 ms. 1st degree AV block is defined by PR intervals greater than 200 ms. This may be caused by drugs, such as digoxin; excessive vagal tone; ischemia; or intrinsic disease in the AV junction or bundle branch system. | Knowledge Weavers ECG | ||
2 | A very subtle 1st degree AV block | Where are the P waves??? They are hiding in the T waves as indicated by the arrows. How do we know? The PVC unmasked the sinus P wave, and now it is seen in the pause following the PVC. The PR interval is, therefore, about 500 ms. | Knowledge Weavers ECG |