Definition of Atrial Fribrillation

After reading so much I am still confused. It seems that afib is separate from irregular heartbeat, tachycardias, brachycardias, PVCs, PACs, etc.

Is there a clear definition of lone atrial fibrillation?

Louise,

tachycardia is a rate faster than 100 BPM (normal during exercise).

bradycardia is a rate less than 60 BPM (normal in someone who works out a lot).

PVC is premature ventricular contraction, in other words the ventricles contract before they "should." Many normal people have some PVC's and never notice them.

PAC is premature atrial contraction, the atria contract before they should. Runs of PAC's can devolve into afib. Many normal people have some PAC's and never notice them.

Irregular heart beat can be anything that is not regular, including PAC's & PVC's

Atrial fibrillation is where the atria beat very fast ~300BPM with reentrant wavelets electrically in the atria. The AV node does not let all these signals through to the ventricles, so the ventricular rate is very irregular. This is contrasted with atrial flutter which also has a very fast atrial rate but the AV node usually lets every 2nd, 3rd or 4th signal through to the ventricles. So the ventricular rate is regular.

The only real way to diagnose is with an ECG. I can "feel" the irregular pulse of afib in my radial pulse and am 100% accurate when I confirm with a monitor, but that's just me.

Lone afib means afib with no underlying heart disease: "absence of clinical or echocardiographic findings of other cardiovascular disease (including hypertension), related pulmonary disease, or cardiac abnormalities such as enlargement of the left atrium." Many afibbers have these underlying conditions and are therefore not "lone."

George



Edited 1 time(s). Last edit at 12/19/2013 12:46AM by GeorgeN.

Great explanation!

George, where does flutter fit in with your above explanation.....ron H

Ron,

I don't have a great description of how the atrial rhythms are different in afib & flutter. Here is an OK description: <[www.bostonscientific.com]

From a "what you feel" perspective, the ventricular rate on afib will feel very irregular whereas the flutter will be very regular. When I've seen flutter (not in myself) on a heart rate monitor, it is even more regular than NSR. That is there is less variability than NSR.

George

Louise - The various types of rhythm disturbances can certainly be confusing. In general, one can feel the difference between a chaotic beat that is 'regularly "irregular" (squirrel in the chest) and the flutter pattern which is a steady, quite comfortable rapid heart beat.

There is a book written by Electrophysiologist, J. Marcus Wharton, MD titled Interpreting Cardiac Dysrhythmias. (c) 1987 that describes every possible cateory of arrhythmia...or as he notes- dysrhythmia. In just the first section on Sinus Rhythm, there are ten identification categories. In total, there are 8 sections in the book on discussion and identification on the distinctions between the various rhythm patterns that appear on an electrocardiogram along with discussions and treatment. There are so many technical nuances that enter into the identification criteria that it is not likely one can diagnose precicesly without ECG.

The best thing you can do is have an ECG while you are in arrhythmia so you can relate to how that rhythm pattern feels and then be able to notice a variation of the same pattern.... like a change from atrial fibrillation to atrial-flutter. I have considerable experience with afib changing to flutter, but I notice that often, the ER people including some of the nurses and doctors are not able to differentiate even though the pattern on the monitor is unmistakable. For me, flutter is typically very regular and comfortable but the heart rate is fast. I'm functional and can walk long distances without distress if the heart rate is not overly rapid. When it gets to around 150 bpm and over, then all I can do is sit quietly while I make plans for an electrocardioversion.

Jackie

Thank you all! George, thank you for the breakdown. I do look at the glossary for definitions; however, when I read different posts people seem to describe or refer to situations differently.

Jackie, once during a discussion of blood thinners you asked why I was put on one in the first place and was I diagnosed with afib. I was, after wearing a holter monitor for 24 hours. The summary was:

"The predominant rhythm was sinus with episodes of atrial tachycardia, atrial flutter, and atrial fibrillation from 35 BPM to 152 BPM, average 64 BPM. Sinus rate average was difficult to calculate because of frequent episodes of atrial tachyarrhythmias. The average ventricular rates during atrial tachyarrhythmias were 100 to 150 BPM. (Word missing on copy) QRS intervals during sinus rhythm were within normal limits. There were occasional PVCs. There were frequent PACs. Actual duration of atrial tacharrythmias was 104.3 minutes. The longest R-R (?) was 2/1 seconds."

A few days after this report I had an echo stress test. They said my BPM was 200 after a minute on the treadmill and immediately took me off (I didn't feel this -- I would have thought I could start running!). They immediately did an echo cardiogram and the tech said I had a "beautiful" heart, with no irregularities. I have never, except at that time, experienced a heart rate of 200 BPM.

So if afib is actually ~300 BPM, I have never had it to my knowledge, although in my head I have lone afib. I will have another echo cardiogram in Feb/Mar after my annual physical to make sure there is still no other sign of heart disease. At that time I will be asked to be referred to an EP, since I have only seen cardiologists.

As always, thank you ALL for your patience and undying support.

Louise

Louise:

I too never had a heartbeat of 300, the highest that has been recorded was 140 which was the first time I had an episode of AF. Now, my rate in AF is In the upper 80s , low 90s, I know because I take my pulse. I don't know how anyone can tolerate a heartbeat of 300, I would think that the heart rate varies in most Afibbers.

Liz

Louise,

The 300 BPM is only in the atria (you won't feel this). The ventricular rate is usually significantly less (fortunately). The ventricular rate is what you feel in your pulse. The signals come from the atria to the AV node. The AV node does not pass all the signals to the ventricles (fortunately), so the ventricular rate is less than the atrial rate. In the case of flutter, it is usually a ratio 2:1, 3:1, 4:1. For example, if the atrial rate is 300, and the ratio is 3:1, the ventricular rate is 100 BPM. There are cases of 1:1 conduction for flutter and these are very uncomfortable - Shannon has had this experience. In the case of afib it is not a set ratio. Afib ventricular rates can vary from low, like 70 to high, like 200 and anywhere in between. Having high ventricular rates (>100) for extended periods of time is a bad thing, can lead to cardiomyopathy and doctors usually prescribe rate control meds to reduce these rates. Also the higher the ventricular rate in afib, generally the more symptomatic it is.

George



Edited 1 time(s). Last edit at 12/19/2013 04:40PM by GeorgeN.

Great explanations George! I'm learning a lot from this thread. Thanks for your help.

Jim

Here's an overview of the electrical conduction system of the heart: <[en.wikipedia.org]
Remember, were talking electrical system. What you feel in your radial (wrist, neck or other point) pulse is a result of the ventricles pumping blood.

Normally, the SA node initiates a signal for the atria. This signal continues to the the AV node, which puts a delay in the signal. This delay allows the atria to beat and fill the ventricles. Then the AV node sends the signal to the ventricles, which contract and push the blood through your system. When you are in afib, you aren't getting any "push" from the atria and this represents about 25% of the volume. So the amount of blood being pushed through your system decreases with afib, for a given heart rate. The atria don't push in afib because they are "fibrillatiing" or quivering and not really pushing.

When you get an echocardiogram, one of the metrics is the ejection fraction. This is how much of the blood in the ventricles is pushed out with each beat. Normal is 55-75%.

George,

Thank you so much for your very clear descriptions. Very, very helpful.

Louise