This is a good rhythm strip to use to illustrate how atrial fibrillation can almost look regular when the rate is fast. Students should be taught how to "march out" the rhythm for regularity. It is always a good idea with atrial fib to take a longer strip, looking for the inevitable "gaps" in the R-to-R intervals. Also, as your students progress, a 12-lead ECG is invaluable to really search for P waves. Even two or three simultaneous leads are better than just one.
Atrial fibrillation with a controlled ventricular response is often considered to be atrial fib that has been controlled with medication. While this is often true, it is possible to see atrial fib with a ventricular rate between 50 and 100 bpm in a patient who has not been treated. The hallmark signs of atrial fib are: no P waves and irregularly-irregular rhythm.
Multiple, simultaneous leads are advised to be sure there are no P waves, and a long rhythm strip is often needed to prove the irregularly-irregular rhythm. Remember, even though this rate is adequate (about 90 bpm), the loss of P waves means no "atrial kick". The atria are not filling the ventricles with a forceful pumping action. Patients can lose a significant percentage - up to 25% - of their cardiac output because of this. Coupled with the risk of stroke from the formation and embolization of blood clots from the sluggish circulation in the atria, it is much preferable to have sinus rhythm at the same rate.
This is a good basic rhythm strip example of atrial fibrillation with a rapid ventricular response showing the identifying characteristics of atrial fibrillation: no P waves, an irregularly-irregular rhythm, and a "fibrillatory" baseline. The wavy baseline will not be seen in all leads in all patients, so it is best to use the first two findings as diagnostic criteria. Atrial fib often appears initially as a rapid rhythm, as the AV node is being bombarded by many impulses from multiple foci (pacemakers) in the atria. Depending upon the AV node's ability to transmit these impulses,however, we could see a slow, normal, or rapid ventricular response.
Atrial fib has very chaotic depolarization of the atrial muscle, resulting in quivering and ineffective pumping of the atria. This loss of "atrial kick" can severely reduce ventricular filling, and can reduce cardiac output by as much as 25%. In patients with a very rapid rate, cardiac output can be further reduced, causing CHF. In addition, the fibrillating atria can form blood clots due to sluggish movement of blood. These clots can embolize and cause stroke. For these reasons, patients with atrial fib are anticoagulated and sometimes the atrial fib is stopped by medical, surgical, or electrical therapy. Recurrence of atrial fib is common after treatment, and for some patients, control of the ventricular rate and anticoagulation become the preferred treatment.
