Atrial Fibrillation
By Rear Adm. Joyce Johnson, D.O., M.A.

This subtle condition can have serious consequences for your health. Fortunately, diagnosis is easy, and treatment reduces long-term effects.

The heart has four chambers—two atria on top and two ventricles below them—that sequentially fill with blood and contract to circulate blood throughout the body. The timing and sequence of the contractions are crucial and are controlled by the heart’s own internal cardiac pacemakers. Normally, each chamber contracts about 70 times a minute, allowing it to fill with blood and empty, thus moving blood efficiently.

Atrial fibrillation occurs when the top two chambers of the heart flutter or quiver, rather than contracting rhythmically. These quivers are so fast and erratic the atria don’t have time to fully fill or empty. This means the ventricles, in turn, can’t fully fill or pump enough oxygenated blood throughout the body. As the heart’s internal pacemakers try to regulate atrial fibrillation, the heart might beat too quickly or too slowly.

When the heart beats too slowly, there is not enough oxygenated blood circulated to meet the body’s needs; when the heart beats too quickly, the ventricles don’t have time to adequately fill between beats, less oxygenated blood is circulated with each beat, and the body doesn’t get enough oxygen. In addition, if blood pools in the atria, clots can form and then travel to the brain, causing a stroke.

Though atrial fibrillation can have serious consequences, for many people it goes unnoticed for years. A doctor often will recognize the “irregular irregularity” of the atrial fibrillation heartbeat when he or she takes a patient’s pulse or listens to the heart with a stethoscope during a physical examination. An EKG will show the altered electrical pathways and the irregular irregularity of the heart rate and confirm a diagnosis of atrial fibrillation.

Treatment of atrial fibrillation or atrial flutter depends on many factors. A doctor will look for predisposing conditions, such as hypoglycemia (low blood sugar), hypoxia (low oxygen) from lung disease, abnormal thyroid function, alcohol or drug use, etcetera, and treat them first.

If the heart is beating too fast, medications such as digoxin or propanolol can be used to slow the ventricular rate. These medications may be needed for years. If the heart is beating too slowly, an atrioventricular sequential pacemaker can be inserted to signal the atria and ventricles so they will contract more normally and improve circulation and oxygenation. Anticoagulants such as aspirin or warfarin can reduce clots and the risk of stroke in chronic atrial fibrillation.

If atrial fibrillation is of relatively recent onset, the heart is normal, and a patient is otherwise healthy, cardioversion can be used to electrically shock the heart back into its normal rhythm. Although this is the best procedure for some patients, it has serious risks and should be considered carefully.