Atrial fibrillation

Atrial fibrillation (also known as AFib or simply AF) is a commonly diagnosed heart condition that is estimated to affect an estimated 2.7 million people in the United States, according to the American Heart Association. It is important to know the symptoms, potential risk factors and causes, and treatments so that you can be as informed as possible should you or anyone you know receive a diagnosis of AFib. This could be a potential life saver.

Definition

Atrial fibrillation is defined as a medical condition where an irregular or abnormal heart rhythm causes electrical signals to be generated in the atria (the upper chambers of the heart) in a chaotic manner.

Basic Overview

In a normal heart, the atria squeezes first, followed by the ventricles (the lower chambers of the heart). The heart should beat (or contract) at a regular rate, which is directed by its electrical system. The impulse that causes the heart to beat starts in the sinoatrial (or SA) node of the right atrium. The SA node adjusts the rate of the heart’s contraction based on factors like activity level and sleep as it travels through the atria from right to left, through the atrioventricular (or AV) node in the middle of the heart (septum) and through the ventricles into the body in a normal (or sinus) rhythm. This occurs an average of 60 to 100 beats per minute during times of rest.

When a heart has atrial fibrillation, the atria does not work in tandem with the ventricles and, instead, contracts with its own rhythm. Instead of having each beat controlled by the SA node, multiple electrical impulses start firing at the same time which causes the erratic pattern. Often, people with AFib can have heart rates of between 300 and 600 beats per minute.

The major issue with atrial fibrillation is that, because the blood isn’t moving through your heart at a regular pace, the body isn’t supplied with the right amount of blood it takes for it to run appropriately.

Symptoms

Many people who have atrial fibrillation do not have any symptoms of the condition, especially in the early stages.

For patients that do exhibit symptoms, the most commonly reported are having an “awareness” of the fact that their heart is beating irregularly and rapidly (these are also medically known as palpitations). People describe it as feeling their heart “flutter” in their chest.

People also complain of dizziness, fatigue, confusion, chest pain/pressure, shortness of breath, difficulty exercising, and/or generalized weakness.

Symptoms of atrial fibrillation may occur intermittently (called paroxysmal), which can result in people not seeking medical care early enough to manage the condition. Recognizing the earlier, mild symptoms are critical to stopping the progression of the condition into something more sinister like heart disease or heart failure.

However, in the majority of cases, atrial fibrillation is persistent or long-standing persistent. In some cases, it can be permanent and a normal rhythm can not be restored despite treatment. 

Diagnosis

Diagnosis of the disease can happen either from a physician recognizing the abnormal heart rhythm during a normal, annual physical exam or by the patient presenting with some of all of the above mentioned symptoms.

When being worked up for atrial fibrillation, physicians will start by viewing the heart’s electrical activity. This can be done in a number of different ways.

  • EKG (or electrocardiogram) – records heart rate and electrical timing. This is the most common diagnostic for atrial fibrillation.
  • ECG (or echocardiogram) – records video of the heart with sound waves
  • CT Scans – 3D x-rays of the heart
  • MRI – a snapshot of the heart using radio waves and magnets
  • Holter monitor – wearable EKG for longer term monitoring (up to a week)

Other tests may be ordered to help diagnose atrial fibrillation or to rule out any other conditions. These may include.

  • Blood tests for liver, kidney, and thyroid function (CMP, TSH, ALT, AST)
  • Chest x-rays to verify there is no lung disease present
  • Cardiac stress tests to check the heart’s response to activity

Causes

There are various physical causes of atrial fibrillation. However, the majority of them stem from factors that either damage or affect the heart – hypertension (elevated blood pressure), myocardial infarction (heart attack), coronary artery disease, abnormalities with the heart’s valves (congenital or otherwise), overactive thyroid/metabolic imbalances, lung diseases (including COPD), previous heart surgeries, pulmonary embolism, and sleep apnea.

It is important to remember that there is no solitary cause of AFib. It is often a combination of the above causes mixed with different risk factors.

Risk Factors

While atrial fibrillation can affect anyone, it is most commonly diagnosed in people age 60 and above.

Certain medications can also increase the chances of having atrial fibrillation – Adenosine (an antiarrhythmic), Digitalis (a cardiac glycoside), and Theophylline (a bronchodilator).  In addition, over the counter medications like decongestants (Sudafed) can increase heart rate and exacerbate symptoms.

Other risk factors include excessive caffeine, alcohol, and/or drug usage, obesity, previous heart disease or sometimes simply just genetics/family history.  Smoking is also said to double the risk of developing atrial fibrillation.

Complications

One of the more common complications of atrial fibrillation is that the irregular rhythm can promote blood clot formation in the heart. If one of those blood clots travels from the heart into the brain, the patient is at risk for having a stroke (or cerebrovascular accident, also known as a CVA). Roughly 15 – 20% of stroke patients have been found to have atrial fibrillation.

Another potential complication of atrial fibrillation is the development of heart disease into full heart failure, which is irreversible.

Prevention

Prevention of atrial fibrillation starts early with living a healthy lifestyle. Patients with known cardiac risk factors should eat a healthy, balanced diet with plenty of servings of fresh fruit and vegetables as well as lean proteins (fish, poultry, beans, and yogurt) and whole grains.

It is also important to limit excessive consumption of caffeine, alcohol, and tobacco.

People with risk factors for the condition should consider adding cardio exercise multiple times weekly, but should check with their physicians prior to starting a new routine to assess safety.

Treatment Options

Depending on the severity, atrial fibrillation can be treated a number of different ways.

Various ways to manage the symptoms with medication are usually where most physicians will start. If this manages the patient’s AFib, it may be unnecessary to pursue any further treatment.

A frequently prescribed category of atrial fibrillation medication is blood pressure reducers. Two different common medication types are used –  beta-blockers and calcium channel blockers. Both of these medication categories work to slow down the heart rate by relaxing the patient’s blood vessels which results in lowering their blood pressure. Examples of beta-blockers include Atenolol (Tenormin), Carvedilol (Coreg), and Propranolol (Inderal and Innopran), and examples of calcium channel blockers include Diltiazem (Cardizem and Dilacor) and Verapamil (Calan SR and Verelan).

In addition to one or more blood pressure medications, physicians will also prescribe a blood thinner to stop the formation of blood clots (and ultimately, prevent a stroke). In fact, in some cases, a blood thinner can actually reduce the rate of blood clot related strokes by between 50 and 70%. Common medications in this category are Aspirin, Heparin, and Warfarin (Coumadin and Jantoven).

Physicians will also often prescribe Digoxin or a channel blocker (sodium channel blockers like Quinidine and/or potassium channel blockers like Dofetilide) to control the patient’s heart rate by managing the rate that the electrical signals move through the heart. Another term for this type of medical therapy is chemical cardioversion, which forces the heart back into a normal rhythm. These medications will need to be started while under physician supervision in a hospital.

If medication fails, additional measures can be taken.

Electrical cardioversion is performed under general anesthesia. This procedure is performed by a trained physician who will deliver electrical shocks directly to the heart to force it back into a normal rhythm, essentially “resetting” it.

Further, more invasive options include cardiac ablation (done through a tube inserted into a blood vessel in the groin that burns off the problematic tissue), Maze and Mini Maze procedures (locks the electrical impulses strictly into specific pathways and can be performed either during a full open heart surgery or through endoscopic keyhole incisions) and a combination of the two called a Convergent procedure.

A pacemaker is the most extreme option, where a machine is inserted into the heart to mechanically create a normal rhythm. This is often the absolute last choice, as it is the most permanent and invasive of all the treatment options.

In short, while atrial fibrillation may seem minor in comparison to more dramatic heart conditions, it should be taken very seriously. Left untreated, it can lead to critical and even possibly lethal complications. However, with awareness of its risk factors, causes, and symptoms, people can seek medical care as soon as they suspect they may have AFib and stop those potential complications before they progress.