Wolff-Parkinson-White Syndrome (WPW Syndrome) is a cardiac abnormality caused by abnormal electric pathways in the heart. Normally, electric conduction in the heart travels from the atria to the ventricles through the AV node. However, in WPW Syndrome, an extra abnormal electric pathway, called the Bundle of Kent, appears. This abnormal pathway is unregulated, causing arrhythmia, pre-excitation, and sometimes tachycardia. Supra-ventricular tachycardia may also result, when the electrical activity re-enters the atria through this pathway. Individuals affected with this syndrome may remain asymptomatic, with only their ECG pattern showing an abnormality. On the other hand, other patients may show symptoms ranging from tachycardia, dizziness, light-headedness, palpitations, or fainting, to even heart failure. The condition is one of the most frequent causes of rapid heart beat in young children. About 1 to 3 people in every 1,000 are affected with this condition; about 60-70% of who are males.
WPW Syndrome can be easily diagnosed on the basis of its characteristically abnormal ECG pattern, with a short PR interval and a slurred QRS complex. Individuals, who show no symptoms, need not take the help of medications. Others however need to be put on antiarrhythmics, and other drugs, such as adenosine. Ablation of the Bundle of Kent tissue is a permanent mode of treatment. This ablation may be either through open-heart surgery, or via radio frequency catheter ablation.
Mutations in the PRKAG2 gene have been identified in a few reported cases of WPW Syndrome. This gene codes for one of the regulatory subunits of the AMP-activated protein kinase complex, an enzyme involved in the sensing of and response to energy demands within cells. Mutations in the PRKAG2 gene may result in WPW Syndrome by allowing the build up of glycogen inside cardiac muscle cells, or by dysregulating certain cardiac ion channels.
Chakraborty et al. (1992) reported successful radiofrequency (RF) ablation of the free wall accessory pathway in a patient with WPW syndrome with resistant supraventricular arrhythmia. This 48-year old patient presented with episodic palpitation with giddiness lasting for 30 minutes over a period of two years. She was also diabetic and hypertensive. Clinically, she was obese with blood pressure of 160/100mmHg, had regular pulse, normal JVP, dual heart sounds with no murmurs and had unremarkable systemic examinations. Investigations revealed fasting blood sugar of 9.5 mmol/l. A short PR interval (100 msec), initial delta wave, and a wide QRS complex were found on resting ECG. Her chest X-ray, echocardiography and thyroid function tests were normal. As she did not respond to different antiarrythmic drugs (Dispyramide, Verapamil, and Amiodarone), three sessions of radiofrequency ablation were done in London, after confirming the location of the accessory pathway (left posterolateral) by electrophysiology study which also showed easy inducibilty of atrioventricular re-entrant tachycardia with a sinus length of 360 msec. Through transfemoral puncture, a standard polaris (2.5 mm/4 mm) was inserted and RF ablation was done after positioning the polaris near the mitral annulus via transeptal route across the left atrium and retrogradely via the left ventricle. The development of pre-excitation tachyarrhythmia after the ablation was prevented by Isoprenalin infusion, and Adenosine infusion during sinus rhythm induced complete AV block. After the procedure, AV interval was 14 msec, v delta 0, AV ratio 12:1, and the electrogram was stable and continuous without any accessory pathway potential. Chakraborty et al. (1992) highlighted that the success of radiofrequency ablation lay in perfect technical skills with precise mapping, accurate catheter placement, and a stable electrode contact with the target tissue, and in order to establish radiofrequency ablation as the treatment of choice in resistant arrhythmias in WPW syndrome, all patients should be followed up for long term. [Chakraborty RN, Shahrabani R, Riyami AM. Radiofrequency ablation of accessory atrioventricular pathways in Wolff-Parkinson-White syndrome. Oman Med J. 1992; 9(2):42-4.]
Venugopalan et al. (2005) reported for the first time on an infant in whom an atrial rhabdomyoma formed the substrate for Wolf Parkinson White syndrome. The 3-month-old girl presented with supraventricular tachycardia and evidence of WPW syndrome. Upon examination, she was found to have a large right atrial rhabdomyoma, which was surgically removed. The symptoms of WPW syndrome disappeared after the surgery.
In a study on the prevalence and clinical features of non compaction cardiomyopathy in Qatar, El-Menyar et al. (2007) detected WPW Syndrome in a patient with non-compaction cardiomyopathy (NCCM). The patient was successfully treated by radiofrequency ablation.