Dr. David Berry
What is atrial fibrillation?
Atrial fibrillation is a very common condition especially among our senior population. The short answer is that it is a type of arrhythmia.
What is an arrhythmia?
Our cardiovascular system is a group of organs in our body that work to provide blood to all of our cells. These organs include our vasculature — the “pipes” that the blood travels through to get around our body.
The other main organ involved in this system is the ever present heart. Our heart is a large muscle that is the pumping mechanism to get our blood through the vasculature and to our cells. It accomplishes this by using chambers which are containers of sorts within the muscle of the heart. These chambers hold the blood until the muscle of the heart contracts and pushes it through our vessels.
Being mammals, we have four of these chambers, two on the left and two on the right. The upper chamber is called the atrium while the lower chamber is called a ventricle.
The ventricles are much more muscular than the atrium.
They pump blood a further distance; to the lungs in the case of the right ventricle and to the body in the case of the left ventricle.
On the other hand, the atrium only has to pump blood to its corresponding ventricle. They don’t need as much strength or musculature.
To address our question we need to understand how the heart muscles know when to contract and how it does it in a coordinated fashion. If all the muscles in the heart controlling all the chambers contracted at the same time the blood would go nowhere.
The answer is, electricity.
Yes, we are full of electrical circuitry and nowhere is this electrical circuitry more important than the heart. Through the movement of sodium and potassium in and out of cells our body creates electrical impulses. These impulses cause muscle tissue to contract and in the case of the heart, squeeze blood around our vessels.
This impulse in a healthy patient starts in a specific area of the right atrium called the SA node. The impulse then spreads in a coordinated pattern to the entire atrium both right and left then to the ventricles.
There is even a special set of cells, called the AV node, between the atrium and ventricles that slows this electrical impulse in order to allow the atrium to completely “squeeze “ all its blood into the ventricles before the ventricles begin to contract.
Now we can address our question with relatively easy understanding. First, an arrhythmia is any type of heart beat that is irregular. In other words, the electrical impulse doesn’t proceed in the usual manner as we’ve just described.
There are many types of arrhythmias.
Some are life-threatening. Others are benign or fairly uneventful.
Fortunately, atrial fibrillation is one of the latter types of arrhythmias.
In atrial fibrillation the electrical impulse does not start at the SA node. Instead the entire atrium contracts at the same time in a weak manner and provides little to no pumping of the blood into the ventricle. Usually, this has little effect on the pumping of the blood to the lungs and body since gravity can push most of the blood to the ventricle without much difficulty.
In some patients, with severe heart disease this small loss of cardiac output can be enough to cause problems but those cases, while not rare, are certainly not the majority.
So what do we do?
When a patient is initially diagnosed with atrial fibrillation they will need a full cardiac evaluation to determine the cause of the arrhythmia which can be many. In addition, when the atrium doesn’t beat correctly the blood in them can begin to clot and those clots to move to the lung or brain. This can result in a life threatening problem.
As such, some patients may require some type of blood thinner.
The good news is that many people live long normal lives