An arrhythmia is a problem with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm.
A heartbeat that is too fast is called tachycardia. A heartbeat that is too slow is called bradycardia.
Most arrhythmia's are harmless, but some can be serious or even fatal. When the heart rate is too fast, too slow, or irregular, the heart may not be able to pump enough blood to the body; lack of blood flow can damage the brain, heart, and other organs.
Understanding the Heart's Electrical System :
To understand arrhythmia's, it helps to understand the heart's internal electrical system. The heart's electrical system controls the rate and rhythm of the heartbeat.
With each heartbeat, an electrical signal spreads from the top of the heart to the bottom. As the signal travels, it causes the heart to contract and pump blood. The process repeats with each new heartbeat.
Each electrical signal begins at the sinoatrial (SA) node. The SA node is located in the right atrium, which is the upper right chamber of the heart. In a healthy adult heart at rest, the SA node fires off an electrical signal to begin a new heartbeat 60 to 100 times a minute.
From the SA node, the electrical signal travels through special pathways in the right and left atria. This causes the atria to contract and pump blood into the heart's two lower chambers, the ventricles.
The electrical signal then moves down to the atrioventricular (AV) node, located between the atrium and the ventricle. Here, the signal slows down just a little, allowing the ventricles time to finish filling with blood.
The electrical signal then leaves the AV node and travels along a pathway called the bundle of His. This pathway divides into a right bundle branch and a left bundle branch. The signal goes down these branches to the ventricles, causing them to contract and pump blood out to the lungs and the rest of the body.
The ventricles then relax, and the heartbeat process starts all over again in the SA node.
A problem with any part of this process can cause an arrhythmia. For example, in atrial fibrillation, a common type of arrhythmia, electrical signals travel through the atria in a fast and disorganized way. This causes the atria to quiver instead of contract.
There are many types of arrhythmia. Most arrhythmia's are harmless, but some are not. The outlook for a person who has an arrhythmia depends on the type and severity of the arrhythmia.
Even serious arrhythmia's often can be successfully treated. Most people who have arrhythmia's are able to live normal, healthy lives.
Arrhythmia Signs and Symptoms :
Many arrhythmia's cause no signs or symptoms. When signs or symptoms are present, the most common ones are:
- Palpitations (feelings that your heart is skipping a beat, fluttering, or beating too hard or fast)
- A slow heartbeat
- An irregular heartbeat
- Feeling hesitation between heartbeats
More serious signs and symptoms include:
- Weakness, dizziness, and lightheaded
- Fainting or nearly fainting
- Shortness of breath
- Chest pain
Arrhythmia Diagnosis :
Arrhythmia's can be hard to diagnose, especially the types that only cause sporadic symptoms. Doctors use several methods to help diagnose arrhythmia, including medical and family history, physical exam, and diagnostic tests.
Which Specialists are Involved ?
Doctors who specialize in the diagnosis and treatment of heart diseases include:
- Cardiologists - these doctors take care of adults who have heart problems.
- Pediatric cardiologists - these doctors take care of infants, children, and young adults who have heart problems.
- Electrophysiologists - these doctors are cardiologists or pediatric cardiologists who specialize in the electrical conduction of the heart.
Medical and Family History
To diagnose an arrhythmia, your doctor may ask about the symptoms you are experiencing, such as fluttering in your chest and whether you feel dizzy or lightheaded.
Your doctor also may ask about other health problems you have, such as heart disease, high blood pressure, diabetes, or thyroid problems. Also, they may ask about your family' s medical history, including:
- Does anyone in your family have a history of arrhythmias?
- Has anyone in your family ever had heart disease or high blood pressure?
- Has anyone in your family died suddenly?
- Are there other illnesses or health problems in your family?
In addition, your doctor will likely want to know what medicines you're taking, including over-the-counter medicines and vitamin or mineral or nutritional supplements, as well as your health habits, such as physical activity, smoking, or use of alcohol or recreational drugs.
Your doctor will listen to the rate and rhythm of your heart and listen for a heart murmur, which is an extra or unusual sound heard during your heartbeat. He or she also will:
- Check for swelling in your legs or feet, which could be a sign of an enlarged heart or heart failure
- Look for signs of other diseases, such as thyroid disease, that could be causing the problem
Diagnostic Tests and Procedures
An EKG is the most common test used to diagnose arrhythmias. It is a simple test that detects and records the heart's electrical activity as it passes through each chamber, heart rate, and rhythm.
A standard EKG only records the heartbeat for a few seconds; therefore, it will not detect arrhythmias that do not happen during the test.
To overcome the possibility of missing an arrhythmia, your doctor, may have you do the next diagnostic test, the portable EKG.
Holter and Event Monitors:
A Holter monitor is a portable EKG that records the heart's electrical signals for a full 24- or 48-hour period, while you do your normal daily activities.
An event monitor is similar to a Holter monitor in that you wear it while doing your normal activities; however, an event monitor only records your heart's electrical activity at certain times.
For many event monitors, you push a button to record your heart when you feel symptoms. Others will start automatically when it senses abnormal heart rhythms.
Some event monitors are able to send data about your heart's electrical activity to a central monitoring station where technicians review the information and send it to your doctor.
You may be required to wear an event monitor for up to 1 to 2 months, or as long as it takes to get a recording of your heart while you are symptomatic.
Blood tests check the level of substances such as potassium or thyroid hormone in the blood that can increase your chances of having an arrhythmia.
Chest x ray:
A chest x ray is a painless test that creates pictures of the structures in your chest, such as your heart and lungs. It can show if the heart is enlarged.
An echo uses sound waves to create a moving picture of your heart. It provides information about the size and shape of your heart and how well your heart chambers and valves are working.
This test also can identify areas of poor blood flow to the heart, areas of abnormally contracting heart muscle, and previous injury to the heart muscle due to poor blood flow.
There are several different types of echo, including stress echo. This test is done both before and after a stress test (see below). A stress echo is usually done to find out whether you have decreased blood flow to your heart after exertion, which is a sign of coronary heart disease (CHD).
A transesophageal echo, or TEE, is a special type of echo that takes pictures of the back of the heart through the esophagus (the passage leading from your mouth to your stomach).
During a stress test, you exercise (or are given medicine if you're unable to exercise) because some heart problems are easier to diagnose when your heart is working hard and beating fast.
These tests may include nuclear heart scanning, echocardiography, and magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning of the heart.
Electrophysiology study (EPS):
This test is used to assess serious arrhythmias. During an EPS, a thin, flexible wire is passed through a vein in your groin or arm to your heart. This wire records the heart's electrical signals.
Your doctor uses the wire to electrically stimulate your heart and trigger an arrhythmia. This allows the doctor to see whether an anti arrhythmia medicine can stop the problem.
Catheter ablation, a procedure used to fix some types of arrhythmia, may be done during an EPS.
Tilt table testing:
This test is sometimes used to help find the cause of fainting spells. For the test, you lie on a table that moves from a lying down to an upright position, as the change in position may cause you to faint.
Throughout the test, your doctor watches your symptoms, heart rate, EKG reading, and blood pressure. They may also give you medicine and then check your response to the medicine.
Coronary angiography uses dye and special x-rays to show the inside of your coronary arteries.
During the test, a long, thin, flexible tube called a catheter is put into a blood vessel in your arm, groin, or neck.
The tube is then threaded into your coronary arteries and the dye is injected into your bloodstream. Special x-rays are taken while the dye is flowing through the coronary arteries.
The dye lets your doctor study the flow of blood through your heart and blood vessels; therefore allowing your doctor to find any blockages that can cause a heart attack.
Implantable loop recorder:
This device is used to detect abnormal heart rhythms. It is implanted under the skin in the chest area by minor surgery.
An implantable loop recorder helps doctors figure out why a person may be having palpitations or fainting spells, especially when these symptoms don’t happen very often. The device can be used for as long as 1 to 2 years.
Common arrhythmia treatments include medicines, medical procedures, and surgery. Treatment is needed when an arrhythmia causes serious symptoms, such as dizziness, chest pain, or fainting. It is also needed if an arrhythmia increases your risk for complications, such as heart failure, stroke, or sudden cardiac arrest.
Medicines called antiarrhythmics, can be used to speed up a heart that’s beating too slow or, inversely, slow down a heart that’s beating too fast. They also can be used to convert an abnormal heart rhythm to a normal, steady rhythm.
Some of the medicines used to slow a fast heart rate, such as in people who have atrial fibrillation, are beta blockers (such as metoprolol and atenolol), calcium channel blockers (such as diltiazem and verapamil), and digoxin (digitalis).
Some of the medicines used to restore an abnormal heartbeat to a normal rhythm are amiodarone, sotalol, flecainide, propafenone, dofetilide, ibutilide, quinidine, procainamide, and disopyramide. These medicines often have side effects, such as make an arrhythmia worse or even cause a different kind of arrhythmia.
People who have atrial fibrillation and some other arrhythmias are often treated with anticoagulants or blood thinners, to reduce the risk of blood clots forming. Aspirin, warfarin (Coumadin®), and heparin are commonly used blood thinners.
Medicines can also control an underlying medical condition, such as heart disease or a thyroid condition, that may be causing the arrhythmia.
Some arrhythmias are treated with a pacemaker, which is a small device that is placed under the skin of your chest or abdomen to help control abnormal heart rhythms.
This device uses electrical pulses to prompt the heart to beat at a normal rate. Most pacemakers contain a sensor that activates the device only when the heartbeat is abnormal.
Some arrhythmias are treated with a jolt of electricity delivered to the heart. This type of treatment is called cardioversion or defibrillation, depending on which type of arrhythmia is being treated.
Some people who are at risk for ventricular fibrillation are treated with a device called an implantable cardioverter defibrillator (ICD). Like a pacemaker, an ICD is a small device that’s placed under the skin in the chest. This device uses electrical pulses or shocks to help control life-threatening arrhythmias.
An ICD continuously monitors the heartbeat. If it senses a dangerous ventricular arrhythmia, it sends an electric shock to the heart to restore a normal heartbeat.
A procedure called catheter ablation is sometimes used to treat certain types of arrhythmia when medicines don’t work.
During this procedure, a long, thin, flexible tube is put into a blood vessel in your arm, groin, or neck. The tube is guided to your heart through the blood vessel. A special machine sends energy through the tube to your heart.
This energy finds and destroys small areas of heart tissue where impulses for an abnormal heartbeat may cause an arrhythmia to start. Catheter ablation is usually done in a hospital as part of an electrophysiology study.
Sometimes, an arrhythmia is treated with surgery. This often occurs when surgery is already being done for another reason, such as repair of a heart valve.
One type of surgery for atrial fibrillation is called "maze" surgery. In this operation, the surgeon makes small cuts or burns in the atria that prevent the spread of disorganized electrical signals.
If coronary heart disease is causing arrhythmias, coronary artery bypass grafting may be recommended to improve blood supply to the heart muscle.
Vagal maneuvers are another arrhythmia treatment. These simple exercises sometimes can stop or slow down certain types of supraventricular arrhythmias. They do this by affecting the vagus nerve, which helps control the heart rate.
Some vagal maneuvers include:
- Holding your breath and bearing down (Valsalva maneuver)
- Immersing your face in ice-cold water
- Putting your fingers on your eyelids and pressing down gently
Vagal maneuvers aren't an appropriate treatment for everyone. Discuss with your doctor whether vagal maneuvers are an option for you.