Atrial fibrillation (Afib) | Circulatory System and Disease | NCLEX-RN | Khan Academy

Atrial fibrillation (Afib) | Circulatory System and Disease | NCLEX-RN | Khan Academy

October 22, 2019 16 By Kody Olson


– Atrial fibrillation
is a heart arrhythmia more commonly know as AFib. It’s one of the
supraventricular tachycardias. In a normal heart, electrical wavelengths are conducted from the
SA node to the AB node in an organized fashion. And since you have
organized conduction going from the SA node to the AV
node you’re going to get concentric or unified
contraction of the atrial tissue. However, in AFib
wavelengths are in disarray. So notice how they’re all
erratic and going everywhere. Because you lose this organized signal, you’re not going to
have unified contraction of the atria, instead with
these erratic wavelengths you’re going to have atrial spasming. It actually kinds of
looks like there’s a bag of worms in the atria and
they’re all moving around, if you can imagine that. Also the wavelengths are
doing their own things, so they’re going to be signaling
the AV node erratically and this is going to lead
to an irregular rhythm, because of the irregular stimulation. Classically the AFib EKG is said to be irregularly irregular. What does that mean? Well notice how the distance between the R-R intervals is
different with each beat. In a normal heart it’s the
evenly spaced R-R intervals. With AFib you have
different distances between the R and the R intervals. Also in AFib there are no
distinct P-waves on EKG. Instead you have the coarse
squiggly lines running through. But there are no distinct
P-waves, that’s because remember the atria is spasming. So you’re not going to get that nice unified concentric
contraction of the atria, so you have these coarse
squiggly lines instead representing the atrial spasm. What are the risk factors
for atrial fibrillation? Well anyone that had
diseased atrial tissue has an increased risk for AFib. And how does atrial
tissue become diseased? Well, with old age, so
the skin in your body tends to get old with age,
so does your atrial tissue. Also anything that causes
the tissue of the atria become inflamed can cause
atrial fibrillation. So imagine if you just had
a recent heart procedure that causes inflammation,
that will increase your risk for atrial
fibrillation and anything that causes atrial enlargement. This includes years of high blood pressure and also certain types
of valve disease like mitral stenosis, certain
types of lung dissease and previously having AFib
can enlarge your atria. Other things that increase your risk, include certain hormonal abnormalities specifically your thyroid hormone and years of alcohol abuse. It’s also worth mentioning
that people who have AFib are at an increased
risk for having strokes. So these people are typically put on some sort of blood thinner medication. Now why are these people at
a higher risk for stroke? When the atria is
spasming blood is going to pool in the atrium. When the atrial tissue is spasming, blood then pools in the
atria and it doesn’t move. And what happens to
blood that doesn’t move? It clots. Now imagine, so I’m drawing
a big clot right here, and imagine if this
clot escaped the atrium, went to the ventrical, and then out to the rest of the circulation, it could go to other
organs, including the brain. and if a clot goes to a
blood vessel that supplies the brain, well that can lead to stroke. Therefore, people who
have had AFib are usually put on blood thinners
which will help prevent clot formation and thereby reduce the risk of certain kinds of strokes.