Atrial Fibrillation IS NOT. In fact, many people may have atrial fibrillation and they may be completely asymptomatic and not know that they have it.
Therefore, instead of the upper chambers of the heart (the atria) contracting in a timed relationship prior to the lower chambers of the heart (the ventricles) the upper chambers of the heart are quivering and bombarding the electrical relay switch to the lower chambers (the AV node) at about 600 times a minute and it is the job the AV node to block these impulses so that a life sustainable heart beat can occur (figure about 60 to 120 beats per minute).
About 2.2 million people in the United States have atrial fibrillation and it is age dependent. The older you become, the more likely it becomes. Less that 1% have it under the age of 50, and over 8% have it over the age of 60, and over 15%, over the age of 80. Men tend to predominate over women...and up to 15% have wha t we would call "Lone Atrial Fibrillation" meaning that there is no discernible underlying heart problem. However, it is most associated with a variety of underlying heart ailments such as general cardiovascular disease, atherosclerotic coronary artery disease, valvular heart disease, hypertensive heart disease, cardiomyopathy, and diabetes.
The greatest problem that people face with atrial fibrillation is the stoke risk. This is because blood is not dynamically squeezed out of the atria before the atrial-ventricular valves shut, but merely passes through passively from the atria to the ventricles. Therefore, some of the blood around the edges and in the appendage may stagnate and thus clot. The overall stroke risk is about 5% per year, ranging from 2% in those with "healthy" hearts and up to 10-15% in hearts that are not healthy. The overall risk ranges from 2 to 7 times in those who have atrial fibrillation versus those without atrial fibrillation.
The reasons why atrial fibrillation occurs is because of what happens to atrial cells as well as atrial electrical integrity due to a whole variety of circumstances. The autonomic nervous system plays a huge role, both the sympathetic nervous system (the release of adrenaline, epinephrine, norepinephrine)...which influences electrical traffic with exercise, stress, excitement, anxiety, and also the parasympathetic nervous system ( the vagus nerve and release of acetyl-choline) which occurs during deeper sleep, and digestion.
Other issues pertain to cellular changes such as stretch, change of shape, fibrosis and inflammation and are related to ischemia, endocrine gland interaction, alcohol and drugs, genetics, and aging.
Therefore, people may have a triggering initiating event in a permissive atrial environment. The triggers are usually found inside the pulmonary veins where they enter into the left atrium. These pulmonary triggers can fire at about 500 to 600 times a minute, and under the influe nce of many things: (consider emotion, stress, sleep, high blood pressure, alcohol, certain drugs, heart failure, ischemia, thyroid and cortisol levels) atrial fibrillation may occur because of the cellular changes occurring in the atria itself.
It is important to not only have an appreciation of what may contribute to the phenomena of atrial fibrillation but also to identify it clinically.
Is it"Paroxysmal", whereby it starts and stops on its own, or is it "Persistent" whereby it starts on its own, but needs help to get back to normal rhythm, either by medication interaction or with cardioversion, or is it "Permanent", which means that you are in it and you live life with it! (Not necessarily a bad thing!)
One must also appreciate the clinical spectrum. People may be either completely asymptomatic and not know they have it, or they may have disabling symptoms and be very and unpleasantly aware that they are in it...and everything in between...and the way the person pre sents themselves allows for different options of how to take care of it. For example, a person who is completely asymptomatic does have the danger and risk of presenting as their very first presentation with a devastating stroke, or with congestive heart failure, Because they had now awareness or knowledge of having atrial fibrillation so therefore they were not on any therapy to take care of it.
Therefore, when I encounter someone with atrial fibrillation, I have to inquire the type: paroxysmal, persistent, permanent; the frequency, the duration, the heart rate, the symptoms, the intensity of the symptoms, the precipitating factors such as exertion, stress, sleep, digestion and bowel function, caffeine, alcohol. I have to appreciate their age. I have to do a full workup to understand what type of heart problems may exist. I have to assess for hypertension, diabetes, cholesterol, thyroid, sleep patterns, etc. An echo, a treadmill, sometimes a stress nuclear imaging study, a h olter monitor all need to be done to provide a thorough understanding of the status and nature of that person's heart functionality.
I need to assess the risk of stoke, and determine whether anti-coagulation should be recommended. Is the risk low, intermediate or high. Does the risk of anti-coagulation warrant the benefit. If someone is younger, and has a normal heart structurally and does not have high blood pressure, or diabetes, the risk of stroke is in the 2 to 2-1/2 % range per year. The risk of having a stroke on an anti-coagulant as well as the risk of having a bleed is in the range of 2 to 2-1/2% per year, so you are trading one evil off as equal to the other evil. But if you are older, and have high blood pressure or diabetes, and you have had prior heart or vascular events, and your heart is weaker, the risk of stroke may be up to 10 to 15%. Therefore, being on an anti-coagulant would be considered beneficial because you lower that risk to 2 to 2-1/2 %, an obvious a dvantage! But what if you are more elderly, and you have a tendency to fall, or you have had a hemorrhagic stroke, or a GI bleed, or a hematology problem that enhances bleeding risk...quite a different story!
This is the first half of what I would like to present to you as regards the phenomenology of atrial fibrillation. Consider it an overview of presentation, problems and causes. The next essay will address aspects of treatment and management. How can you live life well with atrial fibrillation? Can you achieve old age with well being and otherwise good health? What are the choices? Is heart rate control a way to go if you have it? What about restoration and maintenance of Normal Sinus Rhythm? How possible is that? How is that done? What are the medication choices? How well do the medications work? When is a pacemaker appropriate? What about the procedure of an atrial fibrillation ablation? Is is safe? Is it dangerous? How successful is it? Are there things I can do in m y lifestyle that may be of benefit to not getting it?
These are the things I will address in my next "address"!