Comparison of supraventricular tachycardia from concealed bypass tract and Wolff-Parkinson-White syndrome.

Supraventricular tachycardia (SVT) is a common problem. There are 2 types of accessory atrioventricular pathway (AP) causing SVT: one can conduct antegradely (WPW syndrome) and another can conduct only in a retrograde direction (concealed bypass tract or CBT). There are little data of the significance and difference of the two types in Thailand. The objectives of this study were to compare characteristics of patients, accessory pathways and outcome of radiofrequency catheter ablation (RFCA) between the 2 types of accessory pathways. We reviewed the electrophysiology report of patients with supraventricular tachycardia from the accessory pathway who were referred for RFCA. There were 74 males and 74 females at a mean age of 37 years. CBT accounts for 44 per cent of SVT from AP. Compared to CBT, WPW syndrome was more in the right-sided location, more associated with heart disease, a higher number of accessory pathways, more inducible atrial fibrillation and more difficult to do ablation. However, the overall success rate of RFCA was similar. Although the recurrence rate was 8.4 per cent, all patients with recurrence were successfully reablated. We concluded from this study that RFCA is a highly effective method for the treatment for both forms of accessory pathway although there are some differences between WPW syndrome and CBT.

Biosense mapping for ablation of ventricular tachycardia in cardiomyopathy.

Using conventional technology, radiofrequency ablation of ventricular tachycardia in cardiomyopathy is frequently unsuccessful because of hemodynamic instability, multiple foci and recurrences. The Biosense CARTO nonfluoroscopic mapping and navigation system, when used to locate the area of the scar or reentry circuit, has the potential to improve the successful ablation, and reduce the rate of recurrence. We report 2 cases here of ventricular tachycardia in cardiomyopathy in which Biosense mapping was useful to identify the area of scar in 1 case, and the area of microreentry circuits in another. Radiofrequency ablation was possible and successful, while the use of conventional mapping was impossible or had recurrence.

Radiofrequency catheter ablation in pediatrics: experience at Siriraj Hospital.

Tachyarrhythmia is one of the life threatening cardiac electrophysiology problems in children. It also affects quality of life of the patients. Radiofrequency catheter ablation (RFCA) has made a significant impact in the treatment of tachyarrhythmia since 1989. The present report is the first and largest report in Thai children. There have been 24 RFCA procedures in 21 children since it was initially performed at Siriraj Hospital from January 1996 to December 1999. The electrophysiology studies and medical records were analyzed retrospectively. Median age and weight at the time of the procedure were 11 (1.1-13) years old and 38.8 (6.8-78.2) kg respectively. The presenting symptoms were palpitation 66.7 per cent, presyncope 16.7 per cent, congestive heart failure and cardiogenic shock 8.3 per cent, syncope 4.2 per cent, and chest pain 4.2 per cent. Median duration of symptom was 3.5 (0.1-8.0) years. The underlying cardiac arrhythmias were Wolff Parkinson White (WPW) syndrome 50 per cent, concealed accessory pathway 16.7 per cent, atrioventricular node re-entry tachycardia (AVNRT) 16.7 per cent, atrial ectopic tachycardia (AET) 12.5 per cent, and WPW with AVNRT 4.2 per cent. The median fluoroscopy time and procedure time were 25 (4-145) minutes and 125 (60-320) minutes respectively. The median tachycardia cycle length was 332.5 (220-460) seconds. The immediate success rate was 21/24 (87.5%) procedures. The procedural complication was 1/24 (4.2%). Two patients (8.3%) had recurrences of tachycardia and were successfully controlled with antiarrhythmic drugs. Conclusion: RFCA is a safe, effective, and curative procedure with high success rate for pediatric tachyarrhythmias.

Radiofrequency catheter ablation of Wolff-Parkinson-White syndrome: report of 83 cases from Siriraj Hospital.

We described the characteristics of patients and accessory pathway and showed our results of Radiofrequency catheter ablation (RFCA). There were 41 males and 42 females at a mean age of 36 years. Accessory pathway associated with Wolff-Parkinson-White (WPW) syndrome in our population was more prevalent on the right side which is different from previous reports. Most commonly associated heart disease was Ebstein's anomaly. Overall success rate was 96.4 per cent. Right free wall accessory pathway needed a longer procedure time and fluoroscopy time, higher radiofrequency power and more radiofrequency applications compared to other locations. Although the recurrence rate was 12 per cent, all patients with recurrence were successfully reablated. We also described the comparison of our result with previous studies. To our knowledge this is the first report in Thailand with a reasonable number of cases. RFCA is a very effective treatment of WPW syndrome in the Thai population and should be considered in symptomatic patients especially those who are refractory to medication.