Wolff-Parkinson-White Syndrome: Causes and Treatment

Wolff-Parkinson-White Syndrome: Causes and Treatment Overview In a normal heart, the electrical impulses that signal the heart to beat only flow in one pathway, which begins in the sinoatrial node, or SA node, located in the right atrium. When the SA node fires, the single is spread through the right and left atria causing the chambers to contract. The impulses then travel through the atrioventricular node, AV node, which is the bridge that allows the impulses to flow from atria to the ventricles. The AV node slows down the electrical signal before sending it to the ventricles. This slight delay allows the ventricles to fill with blood. When electrical impulses reach the muscles of the ventricles, they contract, causing them to pump blood either to the lungs or to the rest of the body. When the electrical signal reaches the ventricles, the chamber them to contract. In wolf-Parkinson-white syndrome, also known as WPW, an extra conduction pathway to the ventricles reaches the chambers quicker the normal. This is because impulses travel through the extra pathway as well as the normal AV node system. The impulses travel in a circular pattern. This circular pattern causing the heart to beat unusually beating patterns called arrhythmia. The arrhythmias are conserved an electrical abnormalities called pre-excitation syndromes, and they are in many forms. In Wolff-Parkinson-White syndrome, the most common form of arrhythmia is known as paroxysmal supraventricular tachycardia. Many people with WPW also experience atrial fibrillation, an irregular rapid heart rhythm. Wolff-Parkinson-White syndrome is present at birth, but the first symptoms often first appear in teens. WPW is one of the most common causes of fast heart rate in infants and children. The syndrome affects about 1 to 3 people in 1,000 people worldwide, but many do not everyone experience symptoms. IN China 70 percent of cases of abnormal heart, rhythm is due to WPW. The extra electrical pathway in the heart doesnt necessarily cause a fast heartbeat. However, this condition makes it possible for other processes to increase the heartbeat, including: Looped electrical impulses, Disorganized electrical impulses Looped electrical impulses. The problem with a fast heartbeat usually occurs in Wolff-Parkinson-White syndrome because electrical impulses travel down one pathway and up the other one, creating a loop of signals. This condition, called AV reentrant tachycardia, sends impulses to the ventricles at a very rapid rate. The ventricles, as a result, pump very quickly. Disorganized electrical impulses. If electrical impulses dont begin correctly in the right atrium, they may travel across the atria in a disorganized way, causing them to beat very quickly and out of step with each other. This condition is called atrial fibrillation. These disorganized signals also increase the pumping rate of the ventricles to some extent. If theres an extra electrical pathway, as with Wolff-Parkinson-White syndrome, the ventricles can beat even faster. The ventricles dont have time to fill up with blood and dont pump enough blood to the body. This less common condition can be life-threatening. History In 1930, Wolff, Parkinson and White described a distinct electrocardiograph (ECG) pattern in healthy young people with short bursts of tachycardia. In 1933, other doctors noted the reason for this irregular rhythm was a faster passage of impulses traveling through the ventricles. In 1944, doctors confirmed the presence of extra pathways. Causes The extra electrical pathway of Wolff-Parkinson-White syndrome is present at birth. Little known to why the extra pathway delopes, but can be caused by sporadic occurrence, and is linked abnormal gene and inheritance, which accounts for a small a small percentage of cases. In most cases, the cause of Wolff-Parkinson-White syndrome is unknown. Most of WPW occurs randomly in the general population, occurring in about 0.1 to 3.1 per 1,000 persons. men have a higher incidence of WPW than women do, for uknown reasons A small percentage of Wolff-Parkinson-White syndrome is caused by a mutation of the PRKAG2 gene. The mutation of the gene is also linked to hypertrophic cardiomyopathy, a form of heart disease that enlarges and weakens the cardiac muscle of the left ventricle. The PRKAG2 gene codes for a protein that is part of the AMP-activated protein kinase (AMPK) enzyme. AMPK is believed to be involved in the development of the heart before birth, as well helps mangae the energy demands within the heart. Researchers are uncertain how PRKAG2 mutations lead to the development of WPW, but is due to the altered activity of AMP-activated protein kinase in the heart. It is unclear if the changes cause overactivate enzyme or reduce enyme activity. It is know though that the AMPK mutation allows glycogen to build up abnormally within cardiac muscle, as well as being related to changes in the regulation ion channels in the heart, which play critical roles in maintaining the hearts normal rhythm. Most cases of Wolff-Parkinson-White syndrome occur in people with no apparent family history of the condition, and accounts for only a small percentage of all cases of this condition. The inheritory disorder typically has an autosomal dominant pattern of inheritance. Some cases of WPW are inherited. Parents who have accessory pathways may pass them on to their children. Research has indicated that incidence of preexcitation in first-degree relatives could be as high as 5.5 per 1,000 persons. About 7 to 20 percent of patients with WPW also have congenital defects within the heart. Symptoms The extra connection in the heart, called an accessory pathway, that allows electrical signals to bypass the atrioventricular node and move from the atria to the ventricles faster than usual. The accessory pathway also can transmit electrical impulses abnormally from the ventricles back to the atria, causing an additional contraction of the atria, leading to an abnormally fast heartbeat, called tachycardia and other arrhythmias. About 80 percent of people with symptoms first have them between the ages of 11 and 50. Complications of Wolff-Parkinson-White syndrome can occur at any age, although some individuals born with an accessory pathway in the heart never experience any health problems associated with the condition. Resulting symptoms of the arrhythmias are dizziness, a sensation of fluttering or pounding in the chest called palpitations, shortness of breath, fainting, and rarely associated with cardiac arrest and sudden death. Some people have WPW without any symptoms at all. The most common arrhythmia associated with Wolff-Parkinson-White syndrome is called paroxysmal supraventricular tachycardia. A person experiencin an tachycardia episode will have heart rate greater than 230 beats per minute and normal blood pressure. An episode of a tachycardia begin suddenly and last for a few seconds or several hours, and often happen during exercise. Wolff-Parkinson-White syndrome often occurs with other structural abnormalities of the heart or underlying heart disease. The most common heart defect associated with the condition is Ebstein anomaly, which affects the valve that allows blood to flow from the right atrium to the right ventricle (the tricuspid valve). Additionally, Wolff-Parkinson-White syndrome can be a component of several other genetic syndromes, including hypokalemic periodic paralysis (a condition that causes episodes of extreme muscle weakness), Pompe disease (a disorder characterized by the storage of excess glycogen), and tuberous sclerosis (a condition that results in the growth of noncancerous tumors in many parts of the body). Treatments Treatments for WPW depends on the type , frequency, and associated symptoms of the arrhythmias experienced. tachycardia may correct itself, but often needs treatment. The goal of treatments for Wolff-Parkinson-White syndrome is to slow a fast heart rate when it occurs and prevent future episodes. Ways to slow your heartbeat include: Vagal maneuvers. Medications, and surgerys. Whether a person will be treated with medication or with an ablation procedure depends on several factors. These include the severity and frequency of symptoms, risk for future arrhythmias and patient preference. Vagal maneuvers affect the vagus nerve, which is the same nerve that regulate heartbeats, and is usally the first treatment tried. Vagal maneuvers, which include coughing, bearing down as if you are having a bowel movement, and putting an icepack on your face, are often performed during an episode of a fast heartbeat. These actions sometimes resulting in slowed conduction of electrical impulses through the AV node. If vagal maneuvers do not stop the fast heartbeat, often medicine is needed. Often an injection of an anti-arrhythmic medication, such as adenosine, or pill versions of drugs, such as flecainide (Tambocor) or propafenone (Rythmol), may be percribed to be taken in response to episode of a fast heartbeat that doesnt respond to vagal maneuvers. Anti-arrhythmic medications may prevent a fast heart rate all together when taken regularly. Medications are usually given to people who experience frequent arrhythmias who cannot, or do not want to undergo surgery. In people with WPW, whose heart rate can not be controlled with medications, ablation can improve symptoms and cure the abnormal arrhythmias. The most common procedure used to interrupt the abnormal pathway is radiofrequency, also known as or catheter ablation. This procedure involves inserting a catheter in an incision in the groin area and running the catheter to the heart area. Electrodes at the catheter tips are heated to damage (ablate) the extra electrical pathway and prevent it from sending electrical signals. When the catheter reaches the heart, the extra electrical pathway is destroyed using radiofrequency. This procedure is highly effective with a success rate for the procedure ranges between 85 95%, and complications which can include heart injury or infection are uncommon. Successful ablation ends the need for medication. Another procedure done to elevate the symptoms of Wolff-parkinson-white syndrome is cardioversion. cardioversion is a procedure where a shock is delivered to your heart through paddles or patches on your chest. The current affects the electrical impulses in your heart and restores a normal rhythm. Its typically used when maneuvers and medications arent effective. When all other forms of treatments have not worked open-heart surgery is almost 100 percent. However, because radiofrequency catheter ablation is almost as effective and less invasive, surgery for Wolff-Parkinson-White syndrome is now rare. However, surgery is usually done only if the patient must have surgery for other reasons. Social implications A person with WPW have several Social implications they must deal with. Since Wolff-Parkinson-White syndrome often occurs with other structural abnormalities of the heart or underlying heart disease, a person monitor there heart health carefully. In Addition to this several other genetic syndromes, including hypokalemic periodic paralysis (a condition that causes episodes of extreme muscle weakness), Pompe disease (a disorder characterized by the storage of excess glycogen), and tuberous sclerosis (a condition that results in the growth of noncancerous tumors in many parts of the body) must be monitored. Common day substances of Caffeine, Tobacco, Alcohol, and Pseudoephedrine which can contribute tachycardia episoides. This makes the person monitor there exposure to these substances and avoid places of smoking if tobacco causes symptoms. With the relatively new ohio smoking ban helps eliminate this social issue with smoking. References http://www.americanheart.org/presenter.jhtml?identifier=4785 http://www.medicinenet.com/wolff-parkinson-white_syndrome/page2.htm http://www.nlm.nih.gov/medlineplus/ency/article/000151.htm http://my.clevelandclinic.org/heart/disorders/electric/wpw.aspx http://www.mayoclinic.com/health/wolff-parkinson-white-syndrome/ds00923