The electrical pulse of the normal heartbeat begins inThe SA node.

The current then runs along tracts to the AV node.

2nd Degree AV heart block Mobitz I

A 2nd degree heart block Type I or Mobitz I, is commonly referred to a "wienkebach". Remember in the story of "Penny and Quinton" when Quinton suddenly did not come home, then he would come back, try to get close, but then drift further, further away, until he did not come home again. Since "Penny", the p-wave, is initiated in the SA node, in a 2nd degree block, the SA node is trying to pace the heart in a normal fashion, but a "block" or slowing is along the line that is causing the impulse to fail to make it to the bundle branches. So, the p-wave is ever present, but the QRS does not show up sometimes. The major difference on a strip to identify this rhythm is if the PR interval "walks out". It does not have to be in a set of three like the song, "long, longer, longest drop, now you have a weinkebach", it just has a pattern of normal PR intervals, then there is some distancing and then dropped QRS complex, and then the SA node tries again by having a normal PR interval. As you can imagine, this heart rate will be slightly irregular, but a p-wave is present every time that a QRS is present.

What do you do?If this is a new onset and the doctor is unaware, and especially if the rate is bradycardia, you should call the doctor. But make sure you have a 12-lead EKG and you have monitored the patient closely before calling. Sometimes a patient may go in and out of this rhythm. If this is the case, and the patient is unsymptomatic, monitor the patient closely and report on rounds.