Heart disease - Arrhythmia - Heart and Stroke Foundation of Canada

Arrhythmia

Everyone has his or her own normal heart beat rhythm. Some are faster or slower than others. Usually, the heart beats between 60 and 80 times per minute. When you receive a diagnosis of arrhythmia, it is an abnormal heart rhythm for you. The pumping action of your heart is triggered by electrical impulses that begin in your heart's natural pacemaker, called the sinus node (also called sinoatrial or SA node). Arrhythmia may cause your heart to beat too slowly (bradycardia, less than 60 beats per minute) or too quickly (tachycardia, more than 100 beats per minute), or cause uncoordinated contractions (fibrillation).

Symptoms
Diagnosis
Treatments

Types of arrhythmia

Arrhythmias are defined by the speed of the heartbeats: slow and fast. They include bradycardia and tachycardia, with variety of conditions under those two categories.

Slow heartbeat - bradycardia

Bradycardia occurs when your heart beats so slowly that it cannot pump enough blood for your body's needs. If it is not treated, it may cause excessive tiredness, dizziness, lightheadedness or fainting, because not enough blood is reaching the brain. This may be corrected with an electronic pacemaker to help your heart beat normally. Bradycardia occurs for several different reasons:

Sick sinus syndrome
Bradycardia results from a "malfunction" in the sinus node (the heart's natural pacemaker), which makes it fire too slowly. This condition may be caused by increasing age or disease. Some medications can also cause or aggravate a slow heartbeat. The resulting arrhythmia may be temporary or permanent. It can be treated with medication or with an electronic pacemaker.

Heart block
Heart block is the slowing down or interruption of the electrical signal to the lower chambers of the heart (ventricles) which cause the heart muscle to contract. The heart's electrical system normally sends signals from the upper chambers of the heart (atria) to the lower chambers (ventricles) in a pattern that causes a heartbeat, a coordinated contraction of the heart muscle. More

Rapid heartbeat - tachycardia

Tachycardia occurs when your heart beats too fast. There are two main types:

Tachycardia above a ventricle (supraventricular)
These are rapid heartbeats in the atria (the top chambers of your heart) or in the AV (atrioventricular) node – the electrical connection between the atria and the ventricles (the lower chambers of your heart).

Atrial flutter
Atrial fibrillation
Paroxysmal supraventricular tachycardia (PSVT)
Wolff-Parkinson-White (WPW) Syndrome

Atrial flutter
In atrial flutter, an extra or early electrical impulse travels around and around the atria in a circular path rather than down along its normal path. This electrical signal causes the atria to "flutter," contracting at a much higher rate than normal. Atrial flutter is usually not life threatening, but it may still cause chest pain, faintness or other more serious problems.

Atrial fibrillation
This common form of tachycardia occurs when the electrical activity in the atria is disorganized and very rapid. The pattern of electrical activity stimulates the atria randomly and at a high speed, which causes a series of very rapid contractions of the heart's upper chambers, preventing them from pumping effectively. Though not usually life-threatening, the rapid, irregular and uncoordinated beating of the ventricles may cause lightheadedness or palpitations. If it goes on for several days or longer, it may increase your risk of stroke, because blood trapped in the atria can clot and travel from your heart to your brain, causing a stroke. For more information on atrial fibrillation.

Paroxysmal supraventricular tachycardia (PSVT)
This type of tachycardia produces heart rates between 140 and 250 beats per minute. (Normally, the heart beats 60 to 80 times per minute). PSVT usually occurs in people who are born with an extra electrical circuit or pathway between the atria and the ventricles. PSVT often first happens in younger people, but may also start later in life. It may be distressing, but is rarely life-threatening.

Wolff-Parkinson-White (WPW) Syndrome
This is a congenital abnormality (present at birth) involving the heart's electrical system. Most people with WPW syndrome lead normal lives. Many have no symptoms and have no episodes of tachycardia. In some people, WPW syndrome can cause rapid heartbeats (paroxysmal supraventricular tachycardia), with heart rates rising up to 240 beats per minute (The normal rate is 60 to 80 beats per minute). Other symptoms include palpitations, shortness of breath, fainting and possibly angina (chest pain). While the condition is present at birth, symptoms are more likely to appear in adults. WPW is usually diagnosed in adolescence or early adulthood.

Tachycardia in a ventricle

Ventricular tachycardia
Ventricular fibrillation

Ventricular tachycardia
Ventricular tachycardia occurs when the ventricles (the lower chambers of the heart) beat too fast. It may be very serious because the ventricles are responsible for pumping blood to the rest of the body. If tachycardia becomes so severe that the ventricles can't pump effectively, it may be life threatening. Ventricular tachycardia can be treated with medications. Other treatments include an implantable defibrillator, catheter ablation, non-surgical procedures to destroy malfunctioning cells, or surgery to remove damaged heart tissue.

Ventricular fibrillation
Incorrectly timed electrical signals or ones that do not follow normal pathways may set off ventricular fibrillation. Like atrial fibrillation, this happens when the electrical signal that normally triggers a heartbeat splits and goes off on random paths around the ventricles instead of following its normal route. This results in a series of rapid but ineffective contractions of the ventricles. Without immediate treatment, it may be fatal. It is treated by administering an electric shock to the heart, using a machine called a defibrillator. This shock allows the heart to "reset" itself and return to its normal rhythm.

Postural orthostatic tachycardia syndrome (POTS)
People with Postural Orthostatic Tachycardia Syndrome (POTS) have difficulty successfully adjusting to an upright standing posture from a lying down position. POTS commonly occurs in those between the ages of 12 and 50 and typically affects more females than males.

The syndrome is characterized by a rapid heartbeat that can increase from 30 beats to 120 beats per minute within 10 minutes of standing. Other common symptoms include headaches, light-headedness, inability to exercise, extreme fatigue, sweating, nausea, chest discomfort, mental clouding (“brain fog”) and near fainting (syncope). These symptoms must occur in the absence of long-term chronic diseases, certain medications (such as vasodilators, diuretics, antidepressants or anxiolytic agents), and without a drop in blood pressure in order to be defined as POTS.

To diagnose POTS, your doctor will measure your blood pressure and heart rate while you’re lying down and standing up. Measurements are taken immediately after changing positions, as well as at 2, 5, and 10 minute intervals after standing. POTS is frequently misdiagnosed as panic attacks or chronic anxiety. Sometimes a test called a head upright tilt table exam will be performed to help confirm the diagnosis.

Although POTS can be a severely debilitating disorder in some, many patients will slowly improve over time and the majority will respond to treatment regimens.

Symptoms

Arrhythmias may cause blood flow in your brain and body to decrease resulting in heart palpitation, dizziness, fainting, or even death. There are many types of arrhythmias, some have no symptoms or warning signs, some are not very serious and others may be life threatening.

Symptoms vary from person to person depending on how healthy your heart is and the type of arrhythmia you have, how severe it is, how often it happens and how long it lasts. Some arrhythmias do not have any warning signs.

If you have bradycardia, you may feel tired, short of breath, dizzy or faint. If you have tachycardia, your heartbeat might feel like a strong pulse in your neck or a fluttering, racing beat in your chest. You may also feel discomfort in your chest, weakness, shortness of breath, faint, sweaty or dizzy. If you have any of these symptoms, see your doctor immediately.

How is arrhythmia diagnosed?

Your doctor will probably review your medical history and give you a complete physical exam. Then, he or she may want to run a few tests before recommending treatment. These tests may include:

An electrocardiogram (ECG or EKG)
Electrophysiology studies (EPS)
Exercise electrocardiogram (Stress test)
Holter or event monitoring
Tilt-table exam

How is arrhythmia treated?

Many arrhythmias are treatable with lifestyle changes, medications, surgery or other non-surgical techniques. Treatment will depend upon the extent and frequency of arrhythmia.

Lifestyle

Most people with an arrhythmia can lead normal, active lives. Sometimes, lifestyle changes such as avoiding stress, and cutting out alcohol and caffeine (coffee, tea, soft drinks, chocolate, and some over-the-counter pain medicines) may be helpful. There are many other important lifestyle changes you can make that can improve your condition including eating a healthy diet and becoming more physically active. Talk to your doctor about the best way for you to get started.