Wolff Parkinson White syndrome is a condition of the heart in which there is an additional electrical conduction pathway or an extra electrical circuit present in the heart. As this circuit is present in addition to the normal conduction pathway of the heart, if the electrical impulses are transmitted over this extra pathway, it leads to episodes of tachycardia which means an increase in heart rate.
Causes: The normal conduction pathway of the heart includes the sino atrial node to both the atria and from there to the atrioventricular node. From the atrioventricular node the electrical impulses are transmitted to the bundle of his, which traverses through the interventricular septum. Form the bundle of his the impulses travel from the purkinje fibres into the ventricles. Thus the electrical impulses arising from the sino atrial node excite the atria and from there travel to the ventricles through the conduction system and result in the activation of the ventricles. The sino atrial node discharges impulses at a normal rate and in normal condition is the dominant pace maker of the heart muscle. The nodal discharge and conduction occurs in a regular fashion and maintains equal timing between two successive beats. In people suffering from Wolff Parkinson White syndrome, there is an additional or accessory pathway which traverses from the atria to ventricles and this result in a very rapid heart rate which means a tachycardia of the supraventricular type.
Symptoms: Some patients suffering from this condition may be totally asymptomatic. Some patients may have a few episodes of tachycardia which are widely spaced may be over a period of months to years. Other patients may complain of frequent episodes of tachycardia occurring at a rate of once to twice per week. The patient may complain of symptoms such as pain in the chest or chest discomfort or tightness, dyspnoea or shortness of breath which may or may not be related to exertion, light headedness and a feeling of dizziness, fainting and palpitations.
Diagnosis of Wolff Parkinson White Syndrome: When a patient is examined during a period of tachycardia, the heart rate may be greater than about 200 beats per minute. During the episodes the blood pressure may be normal or low. One must know that the heart rate which is normal in adults is about 60 to 100 beats per minute, around 150 beats per minute in infants, neonates and small children. In between the episodes of tachycardia the patient will be completely asymptomatic and the physical examination is completely normal. An electrocardiogram may show an abnormality called the delta wave. As the patient is asymptomatic between the episodes of tachycardia, in order to capture the episodes of tachycardia, the cardiologist may advise a 24 hour Holter monitoring machine test, which helps record the heart rate and rhythm over a period of 24 hours. Another test essential is electrophysiological studies of the heart.
Treatment of Wolff Parkinson White Syndrome: Medical treatment involves administration of antiarrhythmic medications like adenosine, amiodarone etc. In cases where the heart rate does not return to normal with the help of medication, electrical cardioversion may be done. Radiofrequency cather ablation of the accessory pathway is a preferred method of treatment nowadays. It involves ablating the extra pathway and thus restoring the normal electrical conduction of the heart. The success rates of this procedure are about 85 to 95 percent. Open heart surgery is not such a commonly used method of treatment.
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