Most of us have heard this term, and a significant number of us have experienced it – atrial fibrillation, nicknamed “a-fib.” The understanding, diagnosis, and treatment of atrial fibrillation is one of the shining success stories in modern medicine.
This condition’s name is quite revealing. The atria are the “entrance chambers” to the heart’s ventricles. Embedded in a wall of the atria is the starter switch of the heart’s electrical system, the “sinus node.” When things are working properly, the sinus node emits electrical pulses at regular intervals – usually 60-90 times per minute. The electricity flows along organized channels through the atrial walls and into the ventricles, causing the muscle cells there to contract in orderly fashion, enabling the organ to be a powerful pump.
The term “fibrillation” means rapid, disorganized contraction of muscle fibers. In atrial fibrillation, chaotic electrical flow causes rapid, haphazard twitches of the scant atrial muscles which then transmit erratic signals to the ventricle. The resultant heart contraction, or pulse, is fast and irregular.
(Note, a-fib is not the same thing as v-fib, or ventricular fibrillation. In v-fib, none of the heart muscles can pump, and death occurs.)
Atrial fibrillation is the most common heart rhythm problem. Men develop it more frequently than women, and folks with diabetes, high blood pressure, or a history of heart valve problems (especially rheumatic heart disease) are also more prone to it. Stimulant drugs such as caffeine, pseudoephedrine, and cocaine may provoke it, as may withdrawing from alcohol (this is the famous “holiday heart syndrome”). Lyme disease and thyroid disorders are other well-recognized a-fib triggers.
The majority of times, a person with a-fib has no significant symptoms. It can, however, make a person feel tired or dizzy, because when the ventricles are pumping too fast they don’t get enough time to fill up properly, thus they eject less blood than usual with each beat. This reduces blood flow and is called heart failure. Occasionally, the heart failure gets so bad that fluid starts backing up into the lungs; this can become a medical emergency.
Fortunately, atrial fibrillation is quick and easy to diagnose. A physician can detect the fast and irregular pulse in a few seconds, and a simple EKG can reliably confirm the diagnosis.
If someone has a-fib, the first thing doctors want to do is slow down the heart rate. This allows the ventricle more time to fill up in between contractions and usually resolves any troubling symptoms. A variety of medications can be used, and they usually work well to restore an acceptable pulse rate within several days.
Normalizing the pulse rate helps people feel better quickly, but it is now known that even with a nice slow pulse, people with atrial fibrillation are at an increased risk for stroke. Up to 20% of strokes are caused by this heart rhythm problem! This is because when the atria are fibrillating, little eddies of blood can form clots. If the clots then drift into the powerful ventricles, they can then be catapulted to distant organs with the next pulse – and if they land in the brain, circulation is blocked, causing a sudden loss of neurological function (stroke).
For this reason, almost all a-fib sufferers are placed on some sort of blood thinner, even if they feel great and have a nice slow pulse. By preventing blood clot formation, the risk of stroke is greatly reduced.
Nowadays doctors don’t just stop at rate control and blood thinning as ways to improve the health of individuals with this cardiac disorder. Techniques are available to actually cure (“convert”) the chaotic atrial electrical activity back into organized “sinus rhythm”. Powerful drugs were initially the only option but their success was limited and side effects common. In the past few decade, however, safer and more successful interventions have been developed. One is “cardioversion”, which is when a strong jolt of electricity is delivered to the heart to stop it entirely, then restart it. Just like rebooting your computer! More recently, “cardiac ablation” – selectively destroying the trouble-starting tissue in the atria wall by electricity or radio waves, delivered via a long and slender tube threaded through the veins and directly into the heart – has become the procedure of choice. It is estimated to be about 80% effective in curing or improving a-fib.
However, once a person has had a-fib, most doctors still want the patient on some sort of blood thinner long term, even if the abnormal rhythm has been “cured” by the strategies noted above.
Strokes are a major health concern, and you can reduce your stroke risk by making sure you don’t have atrial fibrillation. If you have symptoms, see your doctor right away! And even if you feel fine, a periodic checkup can quickly determine if you have this condition. Treatment of a-fib improves your chance of a long and healthy life.