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Atrial Fibrillation
The most common cardiac arrhythmia, atrial fibrillation, occurs when the normal electrical impulses that are generated by the SA node are overwhelmed by disorganized electrical impulses in the atria.
These disorganized impulses cause the muscles of the upper chambers of the heart to quiver (fibrillate) and this leads to the conduction of irregular impulses to the ventricles.
For ACLS, atrial fibrillation becomes a problem when the fibrillation produces a rapid heart rate which reduces cardiac output and causes symptoms or an unstable condition.
When atrial fibrillation occurs with a (RVR) rapid ventricular rate (rate > 100 beats/min), this is called a tachyarrhythmia. This tachyarrhythmia may or may not produce symptoms. Significant symptoms that occur are due to a reduction in cardiac output.
The following is a list of the most common symptoms.
- palpitations or chest discomfort
- shortness of air and possibly respiratory distress
- hypotension, light-headedness and possibly loss of consciousness
- peripheral edema, jugular vein distention, and possibly pulmonary edema
For the purpose of ACLS, it is important to be able to recognize atrial fibrillation when the patient is symptomatic. On an ECG monitor, there are two major characteristics that will help you identify atrial fibrillation.
- No p-waves before the QRS on the ECG. This is because there are no coordinated atrial contractions.
- The heart rate will be irregular. Irregular impulses that the ventricles are receiving cause the irregular heart rate.
When the heart rate is extremely rapid, it may be difficult to determine if the rate is irregular, and the absence of p-waves will be the best indicator of atrial fibrillation.
ACLS Treatments:
For the purposes of ACLS atrial fibrillation is treated when the arrhythmia/tachyarrhythmia produces hemodynamic instability and serious signs and symptoms.
For the patient with unstable tachycardia due to a tachyarrhythmia, immediate cardioversion is recommended. Drugs are not used to manage unstable tachycardia. The appropriate voltage for cardioverting unstable atrial fibrillation is 120-200 J.
Cardioversion of stable atrial fibrillation should be performed with caution if the arrhythmia is more than 48 hours old and no anticoagulant therapy has been initiated due to the risk of emboli that can cause MI and stroke.
Below is a short video which will help you quickly identify atrial fibrillation on a monitor.
Please allow several seconds for the video to load. (5.11 mb)
Click for next Rhythm Review: Other Tachycardias
abosuyonov says
Thank you .
Just to clarify , even though the ACLS algorithm states that for Unstable Afib we perform synchronized cardioversion, however in reality it appears that for unstable a fib, we stabilize with medications, and once a patient is stable, we cardiovert after doing a TEE. is that correct?
Why don’t we in real life scenario not perform synchronize cardioversion for unstable Afib as it states in ACLS algorithm?
Jeff with admin. says
There is a gray area between stable and unstable with regard to tachycardias like afib and aflutter. If there is no other way of reversing or correcting the unstable condition and cardiac arrest is eminent then synchronized cardioversion is necessary and should be done even if TEE has not been performed.
Kind regards,
Jeff
abosuyonov says
Hello Jeff.
Just to clarify .
For unstable Afib we perform synchronized cardioversion . How can one perform TEE prior to that if pt is symptomatic . It’ll really be almost impossible to do TEE with the symptoms he us experiencing ?
Jeff with admin. says
I personally have never seen a case of unstable afib that needed immediate cardioversion. I have seen some cases of unstable afib that responded well to rate controlling medications, blood pressure infusions, and anticoagulation. After the patient was stabilized with IV medications the TEE is performed and then cardioversion if necessary.
Lets say that a patient is unstable with afib and then has an MI and goes into cardiac arrest (VF). You would take your chances and perform defibrillation. The risks involved in to defibrillating are greater than the risks of thrombus from afib. Hope that makes sense.
Kind regards,
Jeff
Allison says
Gotta say I am taking my recertification tomorrow . I wish I found this sight earlier. Have been looking at it all day. You have really done a great job . Thanks 👍
Desiree Archer says
Have been randomly looking at sites in preparation for ACLS test. I must say this website is EXCELLENT!!! I am a visual learner so the combination learning exceeds my expectation. Thank you Jeff.
Regards
Desiree A.