ECG Of The Century: A Most Unusual 1st Degree AV Block
Frank Yanowitz
Copyright 1996
On Day 1, at a heart rate of 103 bpm the P waves are not clearly defined suggesting an accelerated junctional rhythm. However, on Day 2, at a slightly slower heart rate the sinus P wave suddenly appears immediately after the QRS complex. In retrospect, the sinus P wave in Day 1 was found burried in the preceding QRS; note the notch on the downstroke of the QRS. On Day 3 a normal PR interval was seen. How long can the PR interval get in 1st degree AV block??? No one knows.