• Occasional Atrial Fibrillation Cause
• Occasional Atrial Fibrillation Treatment
• Can Occasional Atrial Fibrillation Be Normal
• Occasional Heart Arrhythmia

The Normal Heart Rhythm

Atrial fibrillation, or Afib, is a common type of arrhythmia, or irregular heartbeat. Often, atrial fibrillation occurs because the electrical system that keeps your heartbeat steady has been. Occasional Atrial Fibrillation (AF) Dr. T March 12, 2011 Ask Doctor T Leave a Comment. Q: I am 43, thin & healthy. I had one 12 hour bout with afib and all heart. Avoiding atrial fibrillation and subsequently lowering your stroke risk can be as simple as foregoing your morning cup of coffee. In other words, some AFib cases are only as strong as their underlying cause. If hyperthyroidism is the cause of AFib, treating the thyroid condition may be enough to make AFib go away.

The heart pumps blood to the rest of the body. During each heart beat, the two upper chambers of the heart (atria) contract, followed by the two lower chambers (ventricles). These actions, when timed perfectly, allow for an efficient pump. The timing of the heart’s contractions is directed by the heart’s electrical system.

The electrical impulse begins in the sinoatrial (SA node), located in the right atrium. Normally, the SA node adjusts the rate of impulses, depending on the person’s activity. For example, the SA node increases the rate of impulses during exercise and decreases the rate of impulses during sleep.

When the SA node fires an impulse, electrical activity spreads through the right and left atria, causing them to contract and force blood into the ventricles.

The impulse travels to the atrioventricular (AV) node, located in the septum (near the middle of the heart). The AV node is the only electrical bridge that allows the impulses to travel from the atria to the ventricles. The impulse travels through the walls of the ventricles, causing them to contract. They squeeze and pump blood out of the heart. The right ventricle pumps blood to the lungs, and the left ventricle pumps blood to the body.

When the SA node is directing the electrical activity of the heart, the rhythm is called “normal sinus rhythm.” The normal heart beats in this type of regular rhythm, about 60 to 100 times per minute at rest.

ECG recording of normal heart rhythm

What is atrial fibrillation?

Atrial fibrillation (AF or AFib) is the most common irregular heart rhythm that starts in the atria. Instead of the SA node (sinus node) directing the electrical rhythm, many different impulses rapidly fire at once, causing a very fast, chaotic rhythm in the atria. Because the electrical impulses are so fast and chaotic, the atria cannot contract and/or squeeze blood effectively into the ventricle.

An ECG recording of atrial fibrillation

Instead of the impulse traveling in an orderly fashion through the heart, many impulses begin at the same time and spread through the atria, competing for a chance to travel through the AV node. The AV node limits the number of impulses that travel to the ventricles, but many impulses get through in a fast and disorganized manner. The ventricles contract irregularly, leading to a rapid and irregular heartbeat. The rate of impulses in the atria can range from 300 to 600 beats per minute.

Occasional Atrial Fibrillation Cause

There are two types of atrial fibrillation. Paroxysmal is intermittent, meaning it comes and goes and continuous is persistent.

What are the dangers of atrial fibrillation?

Some people live for years with atrial fibrillation without problems. However, atrial fibrillation can lead to future problems:

• Because the atria are beating rapidly and irregularly, blood does not flow through them as quickly. This makes the blood more likely to clot. If a clot is pumped out of the heart, it can travel to the brain, resulting in a stroke. People with atrial fibrillation are 5 to 7 times more likely to have a stroke than the general population. Clots can also travel to other parts of the body (kidneys, heart, intestines), and cause other damage.
• Atrial fibrillation can decrease the heart’s pumping ability. The irregularity can make the heart work less efficiently. In addition, atrial fibrillation that occurs over a long period of time can significantly weaken the heart and lead to heart failure.
• Atrial fibrillation is associated with an increased risk of stroke, heart failure and even death.

What causes atrial fibrillation?

Occasional Atrial Fibrillation Treatment

There is no one “cause” of atrial fibrillation, although it is associated with many conditions, including:

Most common causes

• After heart surgery
• Chronic lung disease

Less common causes

• Hyperthyroidism
• Viral infection

Can Occasional Atrial Fibrillation Be Normal

In at least 10 percent of the cases, no underlying heart disease is found. In these cases, AF may be related to alcohol or excessive caffeine use, stress, certain drugs, electrolyte or metabolic imbalances, severe infections, or genetic factors. In some cases, no cause can be found.

The risk of AF increases with age, particularly after age 60.

What are the symptoms of atrial fibrillation?

You may have atrial fibrillation without having any symptoms. If you have symptoms, they may include:

• Heart palpitations - Sudden pounding, fluttering or racing sensation in the chest
• Lack of energy or feeling over-tired
• Dizziness - Feeling light-headed or faint
• Chest discomfort - Pain, pressure or discomfort in the chest
• Shortness of breath - Having difficulty breathing during normal activities and even at rest

Atrial Fibrillation is the most common cardiac arrhythmia (heart rhythm) affecting over 5 million people in the United States with projections up to 20 million people by 2030.1 Physicians define atrial fibrillation as rapid, chaotic electrical impulses in the upper heart chambers known as the atria that result in irregular heartbeats. In the early phases of the disease, abnormal impulses from pulmonary veins—which carry oxygenated blood and connect directly to the left atrium of the heart—trigger the arrhythmia. As the disease progresses, the normal cellular architecture of the atria changes as thicker scar tissue replaces healthy muscle, which in turn causes the atrial fibrillation to worsen. Based on the patient’s symptoms, treatment can include medications or catheter ablation (a minimally invasive procedure) to disrupt the faulty signals (Fig).

Risk factors
Other than rare genetic disorders, atrial fibrillation is an acquired condition. It often presents in the sixth and seventh decades of life, with a lifetime risk of 25% for people who are over 40 years of age. Typical risk factors for atrial fibrillation include age, heart failure, valvular (heart valve) disease, obesity, sleep apnea, hypertension, diabetes mellitus, and alcohol consumption.1 In addition to causing cardiovascular symptoms, it increases stroke risk 5-fold and can lead to heart failure. To determine stroke risks, physicians use the CHADS-VASC score (Table). Based on a score of 2 or more risk factors, anticoagulants (blood thinning medications) are used to reduce the chance of stroke.

Endurance athletes
Cardiovascular exercise is generally beneficial for patients with atrial fibrillation; however, there are some scenarios where exercise can increase the episodes. Endurance exercise including marathon running, triathlons, and similar longduration exercise can increase the risk of developing the condition. One study of endurance athletes showed a 2- to 10-fold increase of occurrence compared to sedentary individuals.2 In endurance athletes, the left atrium is often enlarged and there is usually some degree of cardiac muscle stiffening. A leading theory for increased atrial fibrillation in endurance athletes includes increased vagal tone. When the vagus nerve controls the heart rate through the parasympathetic nervous system, nerve fibers slow the heart rate—this is called vagal tone. Prolonged episodes of heightened vagal tone, necessary for endurance activities but possibly arrhythmia provoking, is the most established theory. In this scenario, increased vagal tone leads to increased heart rate variability and ectopy (a rhythm disturbance) thereby triggering atrial fibrillation. The phenomenon appears to be more common in men and in those under the age of 60. Additionally, theories involving athletes include increased physical stress on the heart, inflammation, prolonged electrolyte imbalance, remodeling of the heart muscle, and increase in pulmonary vein trigger firing.³

Occasional Heart Arrhythmia

Exercise-induced
Most patients with exercise-induced atrial fibrillation usually have the mildest form, which doctors define as episodes lasting less than 1 week. To assess the contribution of heavy exertion, physicians often advise their patients to stop endurance training for 3 months.

Exercise-induced atrial fibrillation is different from that seen in the general population, although the treatment strategies for the condition remain similar. For those with 2 or more risk factors for stroke, physicians often prescribe anticoagulants. Medical treatment of atrial fibrillation in athletes can be challenging since most medications can slow the resting and exertional heart rate thereby limiting the ability to exercise. Physicians often prescribe anti-arrhythmic medications specifically designed to treat the disease; however, these tend to have other types of unwanted side effects. Catheter ablation in the endurance athlete has become a more favorable option since it provides freedom from the condition and can eliminate the need for longterm medications.

How much is too much?
Despite findings of increased atrial fibrillation in endurance athletes, physicians do not recommend stopping exercise as a means to reduce the risk. Recommendations for weekly cardiovascular exercise regimens totaling 150 minutes remain part of standard practice. In fact, one study reported that a monitored diet and exercise program for 3 months after an ablation procedure greatly reduced the rate of recurrence; therefore, exercise plays a beneficial role in care.4 However, researchers need to determine the ideal balance before the risk of atrial fibrillation increases. Strength training, such as moderate weight lifting does not increase or decrease the risks. For athletes taking supplements and consuming energy drinks, there is little information to provide any guidance; however, many of these products contain caffeine and other stimulants that have shown to trigger atrial fibrillation events. The question of “how much is too much” in exertional activities remains unclear.

Don’t overdo it
Atrial fibrillation is a common cardiac arrhythmia that has significant health implications including increased risks of heart failure and stroke. Medications and ablation procedures are often effective along with lifestyle modifications in preventing progression of the condition. Cardiovascular fitness is important in reducing episodes; however, extreme training and endurance events can increase the risks. Moderate exercise training regimens are likely the best strategy to reduce the incidence of atrial fibrillation in athletes.

Author: Michael L Bernard, MD, PhD | New Orleans, LA

References:

1. Morin DP, Bernard ML, Madias C, Rogers PA, Thihalolipavan S, Estes NA 3rd. The State of the Art: Atrial Fibrillation Epidemiology, Prevention, and Treatment. Mayo Clinic Proceedings. 2016 Dec; 91(12):1778-1810.
2. Estes NA 3rd, Madias C. Atrial Fibrillation in Athletes: A Lesson in the Virtue of Moderation. JACC: Clinical Electrophysiology. 2017 Sep;3(9) 921-8.
3. Sanchis-Gomar F, Lucia A. Pathophysiology of Atrial Fibrillation in Endurance Athletes: An Overview of Recent Findings. Canadian Medical Association Journal. 2016 Dec;188(17-18):E433-35.
4. Pathak RK, Middeldorp ME, Meredith M, et al. Long-Term Effect of Goal-Directed Weight Management in an Atrial Fibrillation Cohort. A Long-Term Follow-Up Study (LEGACY). Journal of the American College of Cardiology. 2015 May;65(20):2159–69.

Last edited on January 13, 2021