Atrial Fibrillation
Atrial fibrillation (afib) is an irregular rhythm of the atrium of the heart that can result in blood pooling in the atria of the heart, possibly leading to formation of blood clots that can lead to stroke.
Afib is primarily a disease of the elderly and affects 2.2 million Americans. As many as 30% of all strokes in those of 65 years of age are believed to be caused by atrial fibrillation. More importantly, if you have atrial fibrillation at the age of 65 your chances of surviving for ten years are 30% less than for someone that does not have atrial fibrillation.
What Causes Atrial Fibrillation?
To understand the causes of atrial fibrillation you need to understand the normal pacemaker system of the heart. Your heart's primary pacemaker is located in the sino atrial (SA) node near the upper right atrium of the heart. The electrical impulse generated here takes several pathways through the right and left atrium, eventually meeting up with the atrioventricular node (AV) node near the tricuspid valve. Envision it as a highway … it sits on a ramp for a few milliseconds before hopping onto a superhighway of nerve fibers, from which it gets distributed to the apex of the heart. The result is that the atria contract, forcing blood through the mitral and tricuspid valves. Then shortly afterward, the impulse reaches the apex of the heart. This causes the ventricles to contract, closing the mitral and tricuspid valves and ejecting blood through the aortic and pulmonic valves. This cycle repeats approximately once each second.
Why Does Atrial Fibrillation Occur with Age?
In atrial fibrillation, the atria receive numerous impulses from additional pacemaker sites. These additional pacemaker sites are called rotars and are found wherever veins attach to the heart. As we get older, the tissues of our atria stretch and become fiberous. This is made worse by conditions like valvular disease where backward (regurgitant) flow through the bad valves cause higher pressures within the atria. This stretching of the atria changes the makeup of the normal electrical pathways and allows signals from the rotars to find their way into the conduction system of the heart. This results in uncoordinated and ineffective beating of the atria.
How Does Atrial Fibrillation Progress Over Time?
In most patients, atrial fibrillation initially starts as episodes in which the patient will have bursts of atrial fibrillation. This is called paroxysmal atrial fibrillation and the episodes may last from a few minutes to up to seven days. These episodes can themselves lead to more stretching of the atria. This stretching enlarges the atria over time, making it harder to repair. The larger the left atrial size, the less likely the patient will be able to remain free of atrial fibrillation. As the atria grow in size, the episodes become more frequent and last longer. When the episodes last longer than seven days, the patients is said to be in persistent atrial fibrillation. The persistent atrial fibrillation is said to be long-standing after the patient has had persistent atrial fibrillation for longer than one year.
What are the Treatment Options?
Your treatment options will depend on the severity of your atrial fibrillation. Treatment may include medication, non surgical procedures such as ablation or cardioversion, insertion of a pacemaker, or surgical options such as the Maze Procedure or minimally invasive thoracoscopic ablation.
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