ATRIAL ARRHYTHMIAS

ATRIAL ARRHYTHMIAS - At a Glance

Description:

It is normal for your heart rate to change during the day, depending on your activity level. For example, you can expect your heart rate to increase when you're exercising, but not when you are sitting still.

Any kind of abnormal rhythm or heart rate is called an arrhythmia. Fast, abnormal heart rhythms, with rates over 100 bpm, are called tachyarrhythmias. Supraventricular tachycardia (SVT) is a general term for any fast heart rhythm coming from above the ventricles. 

Anyone can develop an arrhythmia, even a young person without a previous heart condition. However, arrhythmias are most common in people over 65 who have heart damage caused by a heart attack, cardiac surgery, or other conditions. Common SVTs include:

•         Atrial fibrillation
•          Atrial flutter
•          Atrioventricular nodal re-entrant tachycardia (AVNRT)
•          Wolff-Parkinson-White syndrome (WPW)

Atrial fibrillation:

• (AF or AFib) is the most common SVT, affecting more than 2 million Americans in the United States.
•  It is a main cause of stroke, especially among elderly people.
• During AF, the heartbeat produced by the atria is irregular and rapid—typically more than 300 bpm—where muscle fibers in the heart twitch or contract. 
• With such a fast heart rate, the heart does not pump efficiently.
•  This may cause blood to pool and can lead to the formation of clumps of blood called blood clots. 
• A stroke can occur if a blood clot travels from the heart and blocks a smaller artery in the brain (a cerebral artery). About 15% of strokes happen in people with atrial fibrillation.

Atrial Flutter:

• Atrial flutter is similar to atrial fibrillation, with heart rates up to 4 times faster than normal in the atria. It differs from atrial fibrillation (AF) in that the heartbeat is regular, not irregular. 
• With atrial flutter, the electrical signal becomes “trapped” in the right atrium. It repeatedly travels in a circular pattern inside the right atrium, only occasionally “escaping” through the AV node to the ventricles. 
• This causes your atria to beat faster than the ventricles of your heart, at rates between 150 and 450 beats each minute.
•  Most who experience atrial flutter are 60 years and older and have some heart disorder, such as heart valve problems or a thickening of the heart muscle. 
• Atrial flutter also carries the risk of developing blood clots, though not as great as with AF.

AV Nodal Re-entrant Tachycardia (AVNRT)

• AVNRT is the second most common SVT. 
• In a normal heart, there is a single electrical pathway, or “gate,” called an atrioventricular node (AV node). 
• The AV node controls thetiming and direction of the electrical signal as it travels from the upper chambers (atria) to the lower chambers (ventricles) of the heart. 
• With AVNRT, an extra electrical pathway forms which allows the electrical signal to travel backward through the “gate” (AV Node) at the same time, starting another heartbeat. 
• During AVNRT the electrical signals continuously go around the 2 pathways in a circular pattern called re-entry. 
• This can lead to a very fast heart rate of 160 to 220 beats per minute. 
• AVNRT is most common in people in their 20's and 30's but can occur at any age. It is more common in women than in men. 

Wolff-Parkinson-White Syndrome:

• Wolff-Parkinson-White (WPW) syndrome is a group of fast, irregular heart beats caused by extra muscle pathways between the atria and the ventricles.
• In WPW, the pathways cause the electrical signals to arrive at the ventricles too soon, and the signals are sent back to the atria in a loop or short circuit.
• The result is a very fast heart rate. People with this syndrome may feel dizzy, have chest palpitations, or have episodes of fainting.
•  People with WPW may be more likely to develop atrial fibrillation or a more dangerous rhythm called ventricular tachycardia. 
• These pathways are present at birth. People of all ages, including infants, can experience the symptoms related to Wolff-Parkinson-White syndrome.
• Episodes of a fast heartbeat often first occur when people are in their teens or early 20s. 

Causes and Risk Factors:

What are causes and risk factors of atrial arrhythmias?

• As you grow older, the risk of atrial arrhythmias seems to increase, especially after age 60. 
• High blood pressure and coronary artery disease are associated with atrial arrhythmias, as are other heart and lung conditions such as chronic lung disease, disease of the heart valves, and heart failure. 

People without heart disease can develop an arrhythmia for unknown causes, but risk factors can include:

•   Emotional stress
•   Consumption of alcohol, caffeine, diet pills and tobacco
•   Some prescription medications, such as certain cold, cough, allergy medications and  antidepressants
• Some rhythms are present at birth, such as White-Parkinson-White syndrome, in which a group of fast, irregular heart beats is caused by extra muscle pathways between the atria and the ventricles.

Symptoms:

What are symptoms of atrial arrhythmias?

Conduction problems like arrhythmias can go unnoticed. Other times they can cause symptoms, like these:

·         Fainting

·         Dizziness, feeling light-headed

·         Heart fluttering (palpitations)

·         Missed or extra heart beats

·         Weakness

·         Shortness of breath

·         Chest pain

 Diagnosis:

How are atrial arrhythmias diagnosed?

• To diagnose SVT, your doctor will typically use an electrocardiogram (ECG) test. This is a painless test that uses electrode patches on your skin to show how electrical signals travel through your heart. 
• The ECG can be printed out on paper. Your doctor can tell what kind of rhythm you have by looking at the printed pattern of your heartbeat.

Atrial fibrillation ECG:

An atrial arrhythmia is often labeled by how it starts and stops.

• Paroxysmal – starts suddenly then stops on its own
• Persistent – starts and continues until stopped with treatment
•  Permanent or Chronic – a rhythm that prevents a return to a normal heart rate

Treatment:

How are atrial arrhythmias treated?

• Treatment for atrial arrhythmias depends greatly upon you and your symptoms. Generally, your doctor will focus on treatments that help control your heart rate and reduce the risk of blood clots.

Several factors are considered in determining the appropriate method of treatment:

•            Your age
•           Overall health
•          Your personal and family medical history
•          Medications you may be taking for other conditions
•          Underlying diseases or conditions that may contribute to the arrhythmia
•          The nature and severity of the arrhythmia and its symptom
•     Possible treatment options include one or a combination of treatments.

Lifestyle Changes:

These may help improve or reduce the occurrence of an arrhythmia. They may include eating a more heart-healthy diet, limiting or eliminating the amount of caffeine, exercising regularly, and stopping smoking.

Medication:

Blood thinners, such as aspirin or warfarin, are commonly prescribed, to prevent the blood from pooling and causing a blood clot to form.

Two additional types of medications are used to treat arrhythmias: antiarrhythmic medicine, which control the rhythm of the heart, and beta blockers, which control the rate at which the heart beats. They may be used alone or along with other treatments

Cardioversion:

Cardioversion uses electrical energy to change an arrhythmia back to a normal rhythm. By delivering a controlled electric shock through the chest to the heart, cardioverters "shock" the heart back into a normal heart rhythm. It is performed in a hospital while the patient is under heavy sedation. During emergencies, the shock may be delivered through an automatic external defibrillator, or AED.

Cardiac Ablation:

For many patients with atrial arrhythmias, medications cannot effectively control the arrhythmia or may cause serious side effects. For these individuals, a procedure called cardiac ablation may be considered. With cardiac ablation, a catheter is positioned inside the heart to target therapy at the tissue responsible for the arrhythmia.

Some patients may need a pacemaker after an ablation procedure