Ventricular fibrillation

Aneurysm, atherosclerosis, atrial fibrillation, atrial flutter, atrial, atrium, bradyarrhythmia, bradycardia, bradycardic, CABG, cardiac ablation, cardiomyopathy, cardiopulmonary resuscitation, cardioversion, CHF, cocaine, congestive heart failure, coronary artery bypass surgery, CPR, defibrillator, dysrhythmia, ECG, echocardiogram, EKG, electrocardiogram, electrolyte, electrophysiology study, ephedra, fibrillation, Holter monitoring, hypertension, hypotension, hypothyroidism, ICD, implantable cardioverter-defibrillator, long QT syndrome, magnetic source imaging, maze procedure, methamphetamine, mitral valve prolapse, MSI, obstructive sleep apnea, pacemaker, palpitations, paroxysmal, premature heartbeats, pseudoephedrine, SA node, sick sinus, sinoatrial node, stimulant, stroke, supraventricular tachycardia, SVT, syncope, tachyarrhythmia, tachycardia, tacycardic, tilt table testing, vagus nerve, valve, vasovagal syncope, ventricle, ventricular fibrillation, ventricular septal defect, ventricular tachycardia, ventricular, VT, Wolff-Parkinson-White syndrome.

Arrhythmia, also called dysrhythmia, is a disturbance of the heart's normal rhythm. When the heart beats, the electrical impulses that cause it to contract must follow a precise pathway through the heart. Any interruption in these impulses can cause an arrhythmia. Arrhythmias cause the heart to pump blood less effectively.

In an arrhythmia, the heart beats may be too slow (bradycardia, slower than 60 beats per minute), too rapid (tachycardia, greater than 100 beats per minute), too irregular (atrial or ventricular fibrillation), or too early (premature contraction).

Each day, a normal heart contracts about 100,000 times, at a rate anywhere from 60-100 times a minute. Changes in rate brought about by variations in activity, diet, medications, and age are normal and common. During intense exercise, a heart may speed up to 160-180 or more beats a minute. Running up a flight of stairs or being startled by a noise account for normal increases in heart rates as well. The rapid-fire contractions in all these situations are faster than the normal resting heart rate range, yet they pose no danger.

In most people, arrhythmias are minor and are not dangerous. A small number of people, however, have arrhythmias that are dangerous and require treatment. Arrhythmias are also more serious if the individual has other heart problems, such as atherosclerosis (hardening of the arteries) or high blood pressure.

The hollow center of the heart is divided into four sections, called chambers. The two upper chambers in the heart are called the atria (or atrium for one chamber). The two lower chambers in the heart are called ventricles.

The rhythm of the heart is normally generated and regulated by specialized tissue within the sinoatrial (SA) node, which is located within the wall of the right atrium of the heart. SA nodal pacemaker activity normally governs the rhythm of the atria and ventricles. Signals arising in the SA node stimulate the atria to contract and travel to the AV node. The atrioventricular node (AV node) is an area of specialized tissue between the atria and the ventricles of the heart, which conducts the normal electrical impulse from the atria to the ventricles.

Normal rhythm is very regular, with minimal changes. Atrial contraction is always followed by ventricular contraction in the normal heart. When this rhythm becomes irregular, tachycardic (too fast) or bradycardic (too slow), or the frequency of the atrial and ventricular beats are different, it is called an arrhythmia.

In general, arrhythmias that start in the ventricles are more serious than those that start in the atria.

About 14 million people in the United States have arrhythmias.

The most common arrhythmias are atrial fibrillation (also called atrial flutter). As many as two million Americans are living with atrial fibrillation. The number of atrial arrhythmias is related to age and the presence of underlying heart disease. The prevalence approaches 30% following open heart surgery.

Age: With age, the heart muscle naturally weakens and loses some of its tone. This muscle weakening may affect how electrical impulses are conducted. Generally, the older the individual, the more the heart is weakened due to the number of years the heart has beat.

Alcohol consumption: Drinking excessive amounts of alcohol can alter the conduction of electrical impulses in the heart or increase the chance of developing atrial fibrillation. Chronic alcohol abuse may also depress the function of the heart and can lead to cardiomyopathy (heart muscle inflammation), leading to the development of arrhythmia.

Coronary artery disease: Heart diseases such as atherosclerosis (hardening of heart arteries), heart attack, abnormal valves, prior heart surgery, and cardiomyopathy (inflammation of the heart muscle) are risk factors for arrhythmias. When cardiac cells lack oxygen, they become weakened and may lead to arrhythmias. Hypertension, or high blood pressure, may also cause the walls of the left ventricle to thicken, possibly altering how the heart's electrical impulses are conducted. Scarring can result from numerous heart problems, most commonly from a previous heart attack. This scarring may disrupt the initiation or conduction of electrical impulses and cause arrhythmias.

Diabetes: The risk of developing coronary artery disease and hypertension greatly increases with uncontrolled diabetes. In addition, episodes of hypoglycemia (low blood sugar) may also cause an arrhythmia.

Electrolyte imbalance: Electrolytes, such as potassium, sodium, calcium, and magnesium, help trigger and conduct the electrical impulses in the heart. Electrolyte levels that are too high or too low can affect the heart's electrical impulses and contribute to arrhythmia development.

Genetics: Being born with a heart abnormality, such as holes in the heart, may affect the heart's electrical function.

Medications: Over-the-counter (OTC) cough and cold medicines containing pseudoephedrine and certain prescription drugs including amphetamines may contribute to arrhythmia development. The herbal supplement ephedra also increases the risk of arrhythmia, but in early 2004, the U.S. Food and Drug Administration banned ephedra from the marketplace because of such health concerns.

Obesity: Obesity, a known risk factor for developing coronary artery disease, may also increase the risk of developing an arrhythmia.

Obstructive sleep apnea: Obstructive sleep apnea is a sleep disorder that is characterized by periods of stopped breathing repeatedly during sleep, often for a minute or longer and as many as hundreds of times during a single night. This disorder can cause bradycardia and bursts of atrial fibrillation.

Stimulant use: Stimulants, such as caffeine, amphetamines, and nicotine, can cause premature heartbeats and may contribute to the development of more serious arrhythmias. Illicit drugs, such as methamphetamine ("crystal meth") and cocaine, may affect the heart nerve conductivity and lead to many types of arrhythmias or to sudden death due to ventricular fibrillation.

Thyroid problems: The body's metabolism speeds up when the thyroid gland releases excess thyroid hormones. This may cause fast or irregular heartbeats and is most commonly associated with atrial fibrillation. As metabolism slows, the thyroid gland hormone levels decrease, potentially causing bradycardia (slow heart beat).

Others: Tachyarrhythmias (fast arrhythmia) may be triggered by exercise, emotional stress, excessive alcohol consumption, smoking, or use of drugs that contain stimulants, such as cold and hay fever remedies. Bradyarrhythmias (slow arrhythmias) may be triggered by pain, hunger, fatigue, digestive disorders (such as diarrhea and vomiting), or swallowing, which can stimulate the vagus nerve excessively. The vagus nerve, the longest cranial nerve, can cause the heart to stop. In most of these circumstances, the arrhythmia tends to resolve on its own.

Tachycardia:

Tachycardia refers to a fast heart rate (beat), greater than 100 beats a minute. When the heart beats too quickly, the ventricles do not have enough time to fill with blood and cannot effectively pump blood to the rest of the body. The lack of oxygen can cause symptoms including the heart skipping a beat or palpitations, shortness of breath, dizziness, blackouts or fainting, temporary blind spots, chest pain, and even death.

Bradycardia:

Bradycardia refers to a slow heartbeat, or a resting heart rate less than 60 beats a minute. When the heart beats too slowly, not enough oxygen-rich blood flows through the body. Some bradycardias do not produce any symptoms; others do and warrant treatment. Symptoms of bradycardia include fatigue and weakness, dizziness, lightheadedness, fainting, and shortness of breath.

Electrocardiogram (ECG/EKG): An electrocardiogram (ECG/EKG) uses a special recording machine attached to the legs, arms, and chest via 10 electrodes to produce a graphical representation of the electric signals that create heart rhythms. The data obtained from an ECG can be analyzed by doctors to identify an abnormal heart rhythm. Alterations in ECG readings may also represent damaged heart muscle, which may occur after myocardial infarction.

Echocardiogram: An echocardiogram uses a special imaging machine with a microphone-like attachment in order to create a videotaped image of the heart, such as the heart's four chambers, valves, and its movements. In contrast to ECGs (which graphically represent electrical impulses), echocardiograms are created using sound waves, much like an ultrasound. Thus, echocardiograms may also be referred to as cardiac ultrasounds. Both ECGs and echocardiograms are widely used to diagnose a variety of cardiovascular conditions, including myocardial infarction and arrhythmia. Echocardiograms may also be used to identify physical abnormalities that contribute to arrhythmias.

Holter monitoring: Holter monitoring detects irregular heart rhythms. Patients wear a walkman-sized recording box attached to their chest by five adhesive electrode patches for 24-48 hours. Doctors analyze the results to determine if arrhythmia is present.

Exercise stress test: The exercise stress (treadmill) test enables doctors to record the heart's electrical activity that may not occur at rest. The heart will need to pump more and more blood and oxygen to the body as the individual exercises. The test can show if the blood supply is reduced in the arteries that supply the heart. It also helps doctors know the kind and level of exercise appropriate for a patient. The stress test is performed in an exercise laboratory (in a hospital or clinic) where the heart rate and blood pressure are recorded at rest. Sticky electrodes are attached to the chest, shoulders, and hips and connected to the electrocardiogram (ECG or EKG) portion of the stress test machine. The treadmill is then started at a relatively slow warm-up speed, then the slope and speed are increased to simulate exercise stress. The doctor monitors the heart rate, blood pressure, changes in the ECG pattern, irregular heart rhythm, and the individual's appearance and symptoms. The treadmill is stopped when the patient achieves a target heart rate (85% of the maximal heart rate predicted for the patient's age). However, if the patient is doing extremely well at peak exercise, the treadmill test may be continued further. The test may be stopped prior to achievement of the target heart rate if the patient develops significant chest discomfort, shortness of breath, dizziness, or unsteady gait, or if the EKG shows alarming changes or serious irregular heart beats. It may also be stopped if the blood pressure (BP) rises or falls beyond acceptable limits. Please note that the systolic BP (upper number) may normally rise to 200 at peak exercise. At the same time, the diastolic BP (lower number) remains unchanged or falls to a slight degree. In contrast, the BP of patients with hypertension or high BP will show a rise of both systolic and diastolic readings. The latter may rise above 90-100. In preparing for an exercise stress test, healthcare professionals recommend not to eat or drink for three hours prior to the procedure. This reduces the likelihood of nausea that may accompany strenuous exercise after a heavy meal. Diabetics, particularly those who use insulin, will need special instructions from the doctor's office. Also, it is recommended to wear comfortable clothing and shoes that are suitable for exercise. An explanation of the test is provided and the patient is asked to sign a consent form. The risk of the stress portion of the test is very small and similar to what you would expect from any strenuous form of exercise (jogging or running up a flight of stairs). As noted earlier, experienced healthcare professionals are in attendance to manage any rare complications such as sustained irregular heart beats, unrelieved chest pain, or even a heart attack.

Event recorder: An event recorder (loop recorder) is a small portable monitor that may be worn for several weeks. This type of recorder is good for individuals who do not experience symptoms of arrhythmias very often. The monitor "loops" a two-minute recording into its memory, which is continually overwritten. When symptoms are experienced, the individual presses a "record" button on the monitor in order to store a correlating strip of EKG material. The recordings are monitored electronically 24 hours a day from a monitoring station or medical office.

Tilt table test: Tilt table testing is used to diagnose fainting or black-out spells by trying to reproduce the black-out episodes. The individual will be tilted upright to about 60 degrees on a special table for a period of time with continuous recording of ECG and blood pressure.

Electrophysiology (EP) study: The electrophysiology (EP) study allows doctors to acquire more accurate, detailed information and, in many cases, provide treatment during the same session. During an EP study, a specially trained cardiac specialist may provoke arrhythmia events and collect data about the flow of electricity during actual events. As a result, EP studies can help locate the specific areas of heart tissue that give rise to the abnormal electrical impulses or arrhythmias.

Sudden cardiac death: Sudden cardiac death is the sudden, abrupt loss of heart function in an individual who may or may not have diagnosed heart disease. Death occurs unexpectedly. Most cardiac arrests are due to ventricular tachycardia or ventricular fibrillation, while others are due to bradycardia. These events are called life-threatening arrhythmias and are responsible for sudden death. About half of all deaths from heart disease are sudden and unexpected, regardless of the underlying disease.

Congestive heart failure: Congestive heart failure (CHF) is a condition in which the heart cannot pump enough blood to supply the body tissues. CHF can result if the heart is pumping ineffectively for a prolonged period due to an arrhythmia. Sometimes, controlling the rate of an arrhythmia with medication or a pacemaker can lead to improved heart function. CHF can be caused by other factors such as hypertension (high blood pressure), atherosclerosis (hardening of the arteries), and certain medications.

Implantable devices:

Pacemaker: If symptom-producing bradycardias do not have a cause that can be corrected, doctors often treat them with a pacemaker. A pacemaker is a small, battery-powered device that is usually implanted near the collarbone. Pacemakers can be surgically placed into the chest (a permanent pacemaker) through a small incision or they can be worn outside the body (a temporary pacemaker) and attached to the heart through a wire that is threaded through a neck vein. Temporary pacemakers are used only while an individual is in the hospital.

The surgery needed to implant a permanent pacemaker is considered a minor surgical procedure. The procedure may take one to two hours to complete. The area where the pacemaker will be inserted will be numbed with an injection of an anesthetic such as lidocaine (Xylocaine?). The individual should not feel any pain during the procedure and should inform the doctor or staff if they are having pain so that more anesthetic medication may be given. One or more electrode-tipped wires run from the pacemaker through the blood vessels to the inner heart. If the heart rate is too slow or if it stops, the pacemaker sends out electrical impulses that stimulate the heart to beat at a steady, proper rate. The more advanced pacemakers can monitor and pace either the atria or ventricles (or both) in proper sequence to maximize the amount of blood being pumped from the heart. The pacemaker's batteries may need to be changed every five to ten years. It is recommended by the American Heart Association to limit exposure to devices that may interfere with pulse generators such as cellular phones, CB radios, electric blankets, and microwaves.

It is normal for the surgical wound to be somewhat painful and swollen for a few days after the procedure. This can usually be controlled with medications, such as ultram (Tramadol?) or ibuprofen (Motrin?). The wound may also appear mildly red for a few days; however, if the area of redness enlarges, a doctor should be notified due to the potential for a serious infection.

If there are no other problems, most individuals who have a permanent pacemaker surgically implanted can go home the next day. They can usually return to normal activities within six weeks. For several weeks after having a pacemaker implanted, the individual may be asked not to lift more than five pounds or raise the affected arm over their shoulder.

Implantable cardioverter-defibrillator (ICD): An implantable cardioverter defibrillator (ICD) looks very similar to a pacemaker, except that it is slightly larger. It has a generator, one or more leads, and an electrode for each lead. These components work similar to a pacemaker. However, the ICD is designed to deliver an electrical shock to the heart when the heart rate becomes dangerously fast or fibrillates. An ICD senses when the heart is beating too fast and delivers an electrical shock to convert the fast rhythm to a normal rhythm. Some devices combine a pacemaker and ICD in one unit for individuals who need both functions.

The ICD has another type of treatment for certain fast rhythms called anti-tachycardia pacing (ATP). When ATP is used, a fast pacing impulse is sent to correct the rhythm. After the shock is delivered, a back-up pacing mode is used if needed for a short while. The procedure for inserting a pacemaker or an ICD is the same. The procedure generally is performed in an electrophysiology (EP) lab or a cardiac catheterization lab.

Medications:

Many types of tachycardias respond well to anti-arrhythmic medications. Medications do not cure the problem, but they can reduce episodes of tachycardia or slow down the heart when an episode occurs.

Sodium channel blockers: Sodium channel blockers slow the conduction of electrical impulses through the heart. These drugs are used to treat ventricular premature beats, ventricular tachycardia, and ventricular fibrillation and to convert atrial fibrillation to normal rhythm. Side effects include arrhythmias (which can be fatal, particularly in individuals with heart disease), digestive upset, dizziness, light-headedness, tremor, retention of urine, increased intraocular (eye) pressure in individuals with glaucoma, and dry mouth. Examples of sodium channel blockers include disopyramide (Norpace?), flecainide (Tambocor?), lidocaine (Xylocaine?), mexiletine (Mexitil?), moricizine (Ethmozine?), procainamide (Procan?, ProcanSR?), propafenone (Rythmol?), quinidine (Quinidex?), and tocainide (Tonocard?).

Beta blockers: Beta blockers slow the heart rate by reducing the speed of the heart's contractions. Beta blockers are used to treat ventricular premature beats, ventricular tachycardia, ventricular fibrillation, and paroxysmal supraventricular tachycardia. They are also used to slow the ventricular rate in people with atrial fibrillation or atrial flutter. Individuals who have asthma and diabetes should not take these drugs. Examples of beta blockers include atenolol (Tenormin?), metoprolol (Lopressor?, Toprol?, Toprol XL?), nadolol (Corgard?), and propranolol (Inderal?).

Potassium channel blockers: Potassium channel blockers are used to treat ventricular premature beats, ventricular tachycardia, ventricular fibrillation, atrial fibrillation, and atrial flutter. Because amiodarone (Cordarone?) can be toxic, it is used for long-term treatment only in some people who have serious arrhythmias. Bretylium (Bretylol?) is used only for short-term treatment of life-threatening ventricular tachycardias. Side effect of potassium channel blockers include arrhythmias, scarring in the lungs (pulmonary fibrosis), and low blood pressure. Potassium channel blockers include amiodarone (Cordarone?), bretylium (Bretylol?), and sotalol (Betapace?).

Calcium channel blockers: Calcium channel blockers slow the conduction of electrical impulses through the atrioventricular node and are used to slow the ventricular rate in individuals who have atrial fibrillation or atrial flutter and to treat paroxysmal supraventricular tachycardia. Side effects include constipation, diarrhea, low blood pressure, and swollen feet. Calcium channel blockers include diltiazem (Cardizem?, Cardizem CR?) and verapamil (Calan?, Calan SR?).

Digoxin: Digoxin (Lanoxin?, Digitek?) slows conduction of electrical impulses through the atrioventricular node. Digoxin is used to decrease the ventricular rate in people who have atrial fibrillation or atrial flutter and to treat paroxysmal supraventricular tachycardia. The drug is given to infants and children younger than 10 years who have Wolff-Parkinson-White syndrome, but older individuals with the syndrome should not take digoxin. Side effects of digoxin include weight loss, nausea, vomiting, and serious arrhythmias; if the dose is too high, xanthopsia (a condition in which objects appear greenish yellow and have a halo around them) may occur. Digoxin was originally isolated from the foxglove plant (Digitalis purpurea).

Purine nucleoside: Adenosine is an example of a purine nucleoside. Adenosine slows conduction of electrical impulses through the atrioventricular node. Adenosine is used to end episodes of paroxysmal supraventricular tachycardia. People who have asthma are not given this drug. Side effects include acute (short-term) spasm of the airways (bronchospasm) and flushing. Adenosine is used in the hospital setting.

Non-surgical procedures:

Vagal maneuvers: The individual may be able to stop a supraventricular tachycardia (SVT) by using particular maneuvers, which include holding the breath and straining or putting pressure on the diaphragm, dunking the face in ice water, or coughing. A doctor may be able to recommend other maneuvers to halt a fast heartbeat. These maneuvers affect the nervous system that controls the heartbeat (called vagal nerves), often causing the heart rate to slow. A doctor should be alerted immediately if an individual is experiencing SVTs.

Cardioversion: If an individual is having an atrial tachycardia, including atrial fibrillation, the doctor may use cardioversion. Cardioversion is an electrical shock used to reset the heart to its regular rhythm. Usually this is done externally in a monitored setting such as a clinic or hospital. The individual will be given medication for sedation during the procedure, such as midazolam (Versed?).

Cardiac ablation: Cardiac ablation is a relatively non-invasive procedure that involves inserting a catheter (narrow, flexible wires) into a blood vessel, often through a site in the groin or neck. The individual may be sedated. The catheter then is threaded into the heart. The journey from entry point to heart muscle is navigated by images created by a fluoroscope, an x-ray-like machine that provides continuous live images of the catheter and tissue. Once the catheter reaches the heart, electrodes at the tip of the catheter gather data and a variety of electrical measurements are made. The data pinpoints the location of the faulty electrical site. Once the damaged site is confirmed, energy is used to destroy a small amount of tissue, ending the disturbance of electrical flow through the heart and restoring a healthy heart rhythm. The energy may be radio wave energy, which cauterizes (burns) the tissue, or intense cold, which freezes the tissue. Patients rarely report pain, but may experience mild discomfort. After the procedure, the individual remains still for four to six hours to ensure that the entry point incision begins to heal properly. Once mobile again, patients may feel stiff and achy from lying still for hours.

Surgical treatments:

Maze procedure: The maze procedure involves making a series of surgical incisions in the atria. These incisions then heal into carefully placed scars in the atria that form boundaries to force electrical activation to proceed in an orderly manner. The procedure has a high success rate, but because it requires open-heart surgery, it is usually reserved for people who do not respond to other treatments such as medications.

Ventricular aneurysm surgery: In some cases, an aneurysm in the heart is the cause of an arrhythmia. An aneurysm is a bulge in an artery caused by disease or weakening of the vessel wall. If catheter ablation does not work, the individual may need this surgery. Ventricular aneurysm surgery involves repairing the aneurysm that is causing the arrhythmia. By removing the source of the abnormal impulses, the arrhythmia often can be eliminated.

Coronary artery bypass graft surgery (CABG): A coronary artery bypass surgery (CABG) may be recommended if the individual has severe coronary artery disease in addition to frequent ventricular tachycardia. This may improve the blood supply to the heart and reduce the frequency of the ventricular tachycardia. Coronary artery bypass graft (CABG) surgery uses blood vessel grafts, which usually come from the patient's own arteries and veins located in the chest, leg, or arm. The graft goes around the clogged artery to create new pathways for oxygen-rich blood to flow to the heart. Some problems associated with CABG include a heart attack (occurs in five percent of patients), stroke (occurs in five percent with the risk greatest in those over 70 years old), blood clots, death (occurs in one to two percent of individuals), and wound infection (occurs in one to four percent). Infection is most often associated with obesity, diabetes, or having had a previous CABG. In about 30% of patients, post-pericardiotomy syndrome can occur anywhere from a few days to six months after surgery. The symptoms of this syndrome are fever and chest pain. Symptoms can be treated with medications, including antibiotics (for infection), nitroglycerin, and anti-inflammatory drugs. The incision in the chest or the graft site (if the graft was from the leg or arm) can be itchy, sore, numb, or bruised. Some individuals report memory loss, loss of mental clarity, or "fuzzy thinking" following a CABG.

Good scientific evidence:

Magnesium: Intravenous magnesium has been reported to reduce the incidence of atrial fibrillation and cardiac arrhythmia. However, it was not found to affect to length of hospitalization, incidence of myocardial infarction, or mortality.

Use cautiously in patients with bleeding disorders, or in those taking anticoagulants or antiplatelet agents. Use cautiously in patients taking antidiabetic and antihypertensive agents. Use cautiously when magnesium sulfate is used topically for prolonged periods or repeatedly. Use cautiously with antibiotics. Use intranvenous magnesium sulfate with extreme caution in patients with eclampsia. Avoid in patients with atrioventricular heart block. Avoid in patients with renal failure or severe renal disease. Avoid intravenous magnesium in women with toxemia during the first few hours of labor.

Unclear or conflicting scientific evidence:

Aconite: The toxic effects associated with aconitine (a poisonous alkaloid and the active principle of aconite) limit its ability to be used to treat arrhythmia. Additional study is needed in this area.

Aconite is highly toxic and is not safe for human consumption. Avoid with heart disease, irregular heartbeat, hemodynamic instability (abnormal blood flow), and gastrointestinal disorders (such as ulcers, reflux esophagitis, ulcerative colitis, spastic colitis, or diverticulosis). Use cautiously with diabetes or suicidal tendencies. Avoid if younger than 18 years old. Avoid if pregnant or breastfeeding.

Coenzyme Q10: Coenzyme Q10 (CoQ10) is produced by the human body and is necessary for the basic functioning of cells. Promising preliminary evidence suggests that CoQ10 supplements may help reduce the risk of cardiovascular disease, including heart attack and high blood pressure. There is also early data to support the use of CoQ10 in children with mitral valve prolapse. Well-designed clinical trials are needed before a recommendation can be made.

Allergy associated with Coenzyme Q10 supplements has not been reported, although rash and itching have been reported rarely. Stop use two weeks before surgery/dental/diagnostic procedures with bleeding risk and do not use immediately after these procedures. Use caution with history of blood clots, diabetes, high blood pressure, heart attack, or stroke, or with anticoagulants (blood thinners) or antiplatelet drugs (like aspirin, warfarin, clopidogrel (like Plavix?), or blood pressure, blood sugar, cholesterol or thyroid drugs. Avoid if pregnant or breastfeeding.

Corydalis: Early evidence suggests certain compounds found in corydalis may be of benefit for arrhythmia. More studies are needed to confirm these findings.

Corydalis is generally considered safe. Avoid if allergic or sensitive to corydalis. Avoid if taking sedative or hypnotic drugs, drugs that treat abnormal heart rhythms (including bepridil), pain relievers, and anti-cancer drugs. Avoid if pregnant or breastfeeding.

Danshen: There is currently not enough evidence to recommend either for or against the use of danshen for vasovagal syncope (fainting).

Avoid if allergic or hypersensitive to danshen. Use cautiously with altered immune states, arrhythmia, compromised liver function or a history of glaucoma, stroke, or ulcers. Stop use two weeks before surgery/dental/diagnostic procedures with bleeding risk, and do not use immediately after these procedures. Use cautiously if driving or operating heavy machinery. Avoid if taking blood thinners (anticoagulants), digoxin or hypotensives including ACE inhibitors such as captopril, or Sophora subprostrata root or herba serissae. Avoid if pregnant or breastfeeding.

L-carnitine: L-carnitine, or acetyl-L-carnitine, is an amino acid found in the body. L-carnitine has been reported to be beneficial in maintaining a healthy heart. Although preliminary results are promising, well-designed and reported clinical trials investigating the effect of L-carnitine on arrhythmia are lacking.

Avoid with known allergy or hypersensitivity to carnitine. Use cautiously with peripheral vascular disease, hypertension (high blood pressure), alcohol-induced liver cirrhosis, and diabetes. Use cautiously in low birth weight infants and individuals on hemodialysis. Use cautiously if taking anticoagulants (blood thinners), beta-blockers, or calcium channel blockers. Avoid if pregnant or breastfeeding.

Magnesium: Magnesium supplementation has been reported to improve most mitral valve prolapse (MVP) symptoms. Additional study is needed to reach a conclusion.

Use cautiously in patients with bleeding disorders, or in those taking anticoagulants or antiplatelet agents. Use cautiously in patients taking antidiabetic and antihypertensive agents. Use cautiously when magnesium sulfate is used topically for prolonged periods or repeatedly. Use cautiously with antibiotics. Use intranvenous magnesium sulfate with extreme caution in patients with eclampsia. Avoid in patients with atrioventricular heart block. Avoid in patients with renal failure or severe renal disease. Avoid intravenous magnesium in women with toxemia during the first few hours of labor.

Omega-3 fatty acids: There is evidence from multiple clinical studies supporting the intake of omega-3 fatty acid (also known as fish or fish oil) supplements for a healthy heart. Fish oil supplements have been reported to lower triglycerides and reduce the risk of death, heart attack, and stroke in people with known heart disease. Fish oil may also slow the buildup of atherosclerotic plaques (hardening of the arteries) and lower blood pressure slightly. There is promising evidence that omega-3 fatty acids may decrease the risk of arrhythmias. Additional research is needed in this area before a firm conclusion can be reached.

Omega-3 fatty acids may increase the chances of bleeding, especially if the individual is taking blood-thinning medications, such as aspirin or warfarin (Coumadin?). It is important to choose fish and fish oils that are free of heavy metals such as mercury and lead. Avoid if allergic or hypersensitive to fish, omega-3 fatty acid products that come from fish, nuts, linolenic acid, or omega-3 fatty acid products that come from nuts. Use cautiously before surgery.

Relaxation therapy: Limited available study showed that biofeedback assisted relaxation (BFRT) benefits patients with neurocardiogenic syncope. Further study is necessary to confirm these results.

Avoid with psychiatric disorders like schizophrenia/psychosis. Jacobson relaxation (flexing specific muscles, holding that position, then relaxing the muscles) should be used cautiously with illnesses like heart disease, high blood pressure, or musculoskeletal injury. Relaxation therapy is not recommended as the sole treatment approach for potentially serious medical conditions, and it should not delay the time to diagnosis or treatment with more proven techniques.

Traditional Chinese Medicine: Traditional Chinese medicine (TCM) is a broad term encompassing many different methods and traditions of healing, such as acupuncture, herbal medicines, cupping, and moxibustion. They share a common heritage of technique or theory rooted in ancient Chinese philosophy (Taoism) and dating back over 5,000 years. TCM herb combinations have been used to stabilize arrhythmia after viral myocarditis (inflammation of the heart). However, research designs have been weak and more studies of better design are needed before recommendations can be made.

Chinese herbs can be potent and may interact with other herbs, foods, or drugs. Consult a qualified healthcare professional before taking. There have been reports of manufactured or processed Chinese herbal products being tainted with toxins or heavy metals or not containing the listed ingredients. Herbal products should be purchased from reliable sources. Avoid ma huang, which is the active ingredient in ephedra. Avoid ginseng if pregnant or breastfeeding.

Smoking cessation: Smoking is a major risk factor for coronary artery disease that may lead to arrhythmias. Nicotine constricts blood vessels and forces the heart to pump harder. A buildup of carbon monoxide (CO) reduces oxygen in the blood and damages the lining of the blood vessels.

Weight control: Being overweight contributes to other risk factors for arrhythmias, such as high blood pressure and cardiovascular disease. Weight loss of as little as ten pounds may lower blood pressure and improve cholesterol levels.

Exercise: Exercise can lower blood pressure, increase the level of HDL cholesterol (good cholesterol), and improve the overall health of blood vessels and heart. It also helps control weight, control diabetes, and reduce stress. Thirty minutes daily of exercise is normally recommended by healthcare professionals.

Stress reduction: Stress can cause an increase in blood pressure along with increasing the blood's tendency to clot. Managing stress can decrease the chances of developing heart conditions, such as arrhythmia.

Diet: Eating healthy foods is important. A heart-healthy diet should include five or more daily servings of fruits and vegetables, foods rich in soluble fiber (such as oatmeal and beans), foods rich in calcium (dairy products, spinach), soy products (such as tempeh, miso, tofu, and soy milk), and foods rich in omega-3 fatty acids including cold-water fish, such as salmon, mackerel ,and tuna. Pregnant women and women who plan to become pregnant in the next several years should limit their weekly intake of cold-water fish because of the potential for mercury contamination. The U.S. Food and Drug Administration (FDA) has announced that whole grain barley and barley-containing products are allowed to claim that they reduce the risk of coronary artery disease.

Other factors: Avoid stimulants, including medications found in over-the-counter treatments for colds and nasal congestion such as pseudoephedrine and caffeine.

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

American Academy of Family Physicians. .

American Heart Association. .

El Oumeiri B, Casselman F, Geelen P, et al. Surgical treatment of atrial fibrillation. Minerva Cardioangiol. 2007;55(3):369-78. .

Hastenteufel M, Yang S, Christoph C, et al. Image-based guidance for minimally invasive surgical atrial fibrillation ablation. Int J Med Robot. 2006;2(1):60-9. .

Heart Rhythm Society. .

National Institutes of Health. .

Natural Standard: The Authority on Integrative Medicine. .

Reiffel JA, McDonald A. Antiarrhythmic effects of omega-3 fatty acids. Am J Cardiol. 2006;98(4A):50i-60i. .

Ten Tusscher KH, Hren R, Panfilov AV. Organization of Ventricular Fibrillation in the Human Heart. Circ Res. 2007; [Epub ahead of print]. .

Thompson PD, Franklin BA, Balady GJ, et al; American Heart Association Council on Nutrition, Physical Activity, and Metabolism; American Heart Association Council on Clinical Cardiology; American College of Sports Medicine. Exercise and acute cardiovascular events placing the risks into perspective: a scientific statement from the American Heart Association Council on Nutrition, Physical Activity, and Metabolism and the Council on Clinical Cardiology. Circulation. 2007;115(17):2358-68. .

Arrhythmias are classified not only by where they originate but also by the speed of heart rate they cause.

Tachycardia refers to a fast heart rate (beat), greater than 100 beats a minute.

Bradycardia refers to a slow heartbeat, or a resting heart rate less than 60 beats a minute.

Not all tachycardias or bradycardias indicate disease. Sinus arrhythmia refers to the normal increase in heart rate that occurs when the individual breathes in. During exercise, it is normal to develop sinus tachycardia as the heart speeds up to provide body tissues with more oxygen-rich blood.

Atrial tachycardias:

Atrial fibrillation: Atrial fibrillation is a common arrhythmia and affects mainly older people (60 years and older). Atrial fibrillation is due to normal wear and tear on the heart muscle and also due to cardiovascular problems such as hypertension (high blood pressure). During atrial fibrillation, the electrical activity of the atria becomes uncoordinated. The atria beat so rapidly, as fast as 350-600 beats a minute, that instead of producing a single, forceful contraction, they fibrillate (quiver). Atrial fibrillation can be intermittent, lasting a few minutes to an hour or more, before returning to a regular heart rhythm. Atrial fibrillation can also be chronic, causing an ongoing problem. Atrial fibrillation is seldom a life-threatening arrhythmia.

Atrial flutter: Atrial flutter is similar to atrial fibrillation and both can coexist in the heart. The key distinction is that atrial fibrillation is characterized by 350-600 beats per minutes and atrial flutter is characterized by 200-400 beats per minute.

Supraventricular tachycardia (SVT): Supraventricular tachycardia (SVT) is a broad term that includes many forms of arrhythmia originating above the ventricles. SVTs usually cause a burst of rapid heartbeats that begin and end suddenly and that can last from seconds to hours. SVT may cause the heart to beat 160-200 times a minute. Symptoms of SVT are generally not life-threatening in an otherwise normal heart, although these arrhythmias may feel quite uncomfortable. SVTs are common in young people.

Wolff-Parkinson-White syndrome: One cause of SVT is known as Wolff-Parkinson-White syndrome. This arrhythmia is caused by an extra electrical pathway between the atria and the ventricles. This pathway may allow electrical current to pass between the atria and the ventricles without passing through the atrioventricular node (AV node) leading to short circuits and rapid heartbeats.

Ventricular tachycardias:

Ventricular tachycardia (VT): Ventricular tachycardia (VT) is a fast, regular beating of the heart that is caused by abnormal electrical impulses originating in the ventricles. Often, VTs are due to a short circuit around a scar from a previous heart attack. VTs can cause the ventricles to contract more than 200 beats a minute. Sometimes, ventricular tachycardias last for 30 seconds or less and are usually harmless, although they cause inefficient heartbeats. Still, an unsustained VT may be a predictor for more serious ventricular arrhythmias, such as longer lasting (sustained) VT. An episode of sustained VT is a medical emergency. It may be associated with palpitations, dizziness, fainting, or possibly death. Without prompt medical treatment, VT often turns into ventricular fibrillation. Rarely, VT occurs in a normal heart.

Ventricular fibrillation: About 300,000 Americans die every year of sudden cardiac death believed to be caused by ventricular fibrillation. With ventricular fibrillation, rapid, chaotic electrical impulses cause the ventricles to quiver uselessly instead of pumping blood. Without an effective heartbeat, the blood pressure falls rapidly, cutting off blood supply to vital organs, including the brain. Most individuals lose consciousness within seconds and require immediate medical assistance including cardiopulmonary resuscitation or CPR. The chances of survival may be increased if CPR is given until the heart can be shocked back into a normal rhythm with a machine called a defibrillator. Without CPR or defibrillation, death results in minutes. Most cases of ventricular fibrillation are linked to some form of heart disease. Ventricular fibrillation is frequently triggered by a heart attack.

Long QT syndrome: Long QT syndrome is a rare arrhythmia that can either be an inherited condition or one that occurs naturally. In older adults, long QT syndrome may be triggered by certain medications, including antibiotics and antifungals, antidepressants, antihistamines, antipsychotics, cholesterol-lowering drugs, diabetes medications, diuretics, and heart medications. Individuals with low potassium, magnesium, or calcium blood levels, such as those with the eating disorder anorexia nervosa, may be susceptible to prolonged QT intervals.

Bradycardias:

Although a heart rate below 60 beats a minute while at rest is considered bradycardia, a low resting heart rate does not always signal a problem. If an individual is physically fit, they may have an efficient heart capable of pumping an adequate supply of blood with fewer than 60 beats a minute while at rest. However, if the individual has a slow heart rate and the heart is not pumping enough blood, bradycardias may develop.

Sick sinus: If the pace-making sinus node is not sending impulses properly, the heart rate may be too slow or it may speed up and slow down intermittently. If the sinus node is functioning properly, sick sinus can be caused by an impulse block near the sinus node that is slowing, disrupting, or completely blocking conduction.

Conduction block: Conduction block of the heart's electrical pathways can occur in or near the AV node or along pathways that conduct impulses to each ventricle. Depending on the location and type of block, the impulses between the atria and ventricles may be slowed or partially or completely blocked. If the signal is completely blocked, certain cells in the AV node or ventricles are capable of initiating a steady, although usually slower, heartbeat. Some blocks may cause no signs or symptoms and others may cause skipped beats or bradycardia. Even without signs or symptoms, a conduction block is usually detectable on an electrocardiogram (ECG), which is a machine that detects and visually shows heart rhythm. Since some blocks are caused by heart disease, an ECG showing a block may be an early sign of heart problems.

Premature heartbeats:

Premature heartbeats can originate in either the atria or the ventricles. Although it often feels like a skipped heartbeat, a premature heartbeat is actually an extra beat between two normal heartbeats.

Premature heartbeats may indicate a more serious heart condition. However, a premature beat can trigger a longer lasting arrhythmia, especially in individuals with heart disease such as hypertension (high blood pressure). These types of arrhythmias are commonly caused by stimulants, such as caffeine from coffee, tea, soft drinks, over-the-counter cold remedies containing pseudoephedrine, and some asthma medications such as albuterol (Proventil?).

Others:

Fainting (syncope): Fainting or syncope is a sudden loss of consciousness. It most often occurs when the blood pressure is too low (hypotension) and the heart does not pump a normal supply of oxygen to the brain. Typically, a faint lasts only a few seconds or minutes and then the individual regains consciousness. Syncope (fainting) is a common problem that affects one million people in the United States every year. About one-third of individuals will faint at least once during a lifetime. A single fainting spell usually is not serious. It may be explained by factors such as stress, grief, overheating, dehydration, exhaustion, illness, or arrhythmias.

Mitral valve prolapse: The mitral valve is between the heart's left atrium and left ventricle. It has two flaps that open and close together like a pair of swinging doors. When the heart beats, the left ventricle pumps blood out to the body and the flaps swing shut. This keeps the blood in the ventricle from going back into the left atrium. In an individual who has mitral valve prolapse (MVP), one or both of the valve's flaps swing up into the atrium as they close. In some individuals, the flaps will still close completely, but in others, they may not shut properly. When the flaps don't close correctly, blood can leak back into the left atrium. This can happen because the flaps are too floppy, too big, or have the wrong shape.

Usually MVP does not cause health problems. Most individuals will continue to lead normal lives and many have no symptoms. In some individuals, the flaps of the mitral valve make a clicking sound when they close. A doctor may hear this when listening to the heart with a stethoscope. Individuals with MVP may also have a heart murmur. A heart murmur is the sound caused by the leaking blood. Individuals with MVP may also may feel dizzy or light-headed, feel anxious, be really tired, be out of breath when playing or exercising, feel that their heart is skipping beats or beating very fast, have chest pain, or have fainting episodes. Symptoms of MVP in children may go away as they age.