Reversibility of tachycardiomyopathy after successful radiofrequency catheter ablation: intermediate results.

Left ventricular function in patients with tachycardia induced cardiomypopathy can improve after cessation of the arrhythmia. We reported the intermediate results of 10 patients, 6 men and 4 women, with tachycardiomyopathy who successfully underwent radiofrequency catheter ablation (RFCA) for incessant tachycardia. Three had right atrial tachycardia, 5 ventricular tachycardia (2 and 3 from the right and left ventricles, respectively), 1 atrial flutter and 1 right accessory pathway. During the mean follow-up period of 19 months (range 11-38 months), one patient, right atrial tachycardia, had recurrence and reablation was successfully done without recurrence. Left ventricular ejection fraction, endsystolic and diastolic diameters from echocardiography gradually improved from 35 per cent, 51 and 61 mm to 58 per cent, 36 and 52 mm, respectively (p<0.001). The mean duration of reversibility was 7 months (range 1-15 months). There was no recurrence of tachycardiomyopathy after the return of left ventricular function. Conclusion, RFCA can terminate tachyarrhythmia and lead to significant improvement of left ventricular diameters and systolic function in patients with tachycardia induced cardiomyopathy.

Myocardial injury after radiofrequency catheter ablation.

Radiofrequency catheter ablation has been a good treatment option for various types of cardiac arrhythmia. However there is concern about myocardial injury associated with radiofrequency catheter ablation. We studied myocardial injury with biochemical markers and echocardiogram in 41 consecutive patients who underwent electrophysiology study (EP study) and radiofrequency catheter ablation (RFCA) at our institute from April to July 2000. The concentration of biochemical markers (CK-MB mass, troponin T and myoglobin) and result of the echocardiograms were analyzed with other characteristics. In 41 patients subjected to EP study with possible RFCA, abnormal levels of troponin T, CK-MB mass and myoglobin were found in 46 per cent, 15 per cent and 44 per cent immediately after procedure, which went up to 64 per cent, 22 per cent and 2 per cent at twenty four hours. Compare to the group with normal troponin T level, the patients with abnormal level at 24 hours after RFCA had a longer procedure time (119+/-44 min. vs 90+/-22 min.), more frequent use of impedance ablation catheters (65% vs 27%), more RF applications (9+/-8 vs 18+/-16) and more ventricular ablation sites (69% vs 9%). The echocardiogram results showed no remarkable abnormality in any patients. Troponin T was the most sensitive marker to detect thermal myocardial injury associated with radiofrequency catheter ablation. Prolonged procedure time, RF applications, the use of impedance ablation catheter and ventricular ablation site were associated with elevated troponin T concentration after RFCA.

Effect of atenolol on symptomatic ventricular arrhythmia without structural heart disease.

Ventricular arrhythmia (VA) from right ventricular outflow tract (RVOT) is a common problem. Symptomatic patients are usually treated with beta-blockers. There is little data on the systematic evaluation of the drug efficacy. The objectives of this study were 1) To determine proportion of exercise induced ventricular arrhythmia among patients with symptomatic ventricular arrhythmia and 2) to determine the response to beta blockers and the correlation between the response to betablockers and exercise induced VA. We prospectively studied 46 consecutive patients with symptomatic ventricular arrhythmia. Patients recorded their symptom scores underwent exercise testing and 24-hour ambulatory monitoring before treatment and 1 month after atenolol. Exercise induced ventricular arrhythmia was demonstrated in 28 per cent of patients with symptomatic ventricular arrhythmia. Atenolol improves symptoms, decreases PVC count from ambulatory monitoring, increases exercise duration and suppresses malignant form of VA during exercise. These effects are at a similar extent in both groups of patients: those with and without exercise induced VA. However, the effect on ventricular arrhythmia suppression during exercise of atenolol was seen only in patients with increased PVC during exercise. In conclusion, atenolol is a good option in treating patients with symptomatic VA from RVOT regardless of the pattern of PVC response to exercise. Atenolol can suppress PVC during exercise testing better in patients with exercise induced VA compared to those without.

Electromagnetic interference of permanent pacemakers by mobile phones in Thailand.

The possible permanent pacemaker function interference by mobile telephones is concerned worldwide. Previous studies from the other countries with different mobile telephone systems and permanent pacemakers provided useful but indirect information. We in vitro studied the interaction between local mobile telephones and permanent pacemakers in Thailand. Seventeen mobile telephones from different systems and brands were tested in the laboratory with seven permanent pacemakers from different companies. We found no interference in the function of permanent pacemakers. The application of the information may be limited from the in vitro nature of the study. However this would be the useful reference for the future in vivo study.

The prevalence of left ventricular hypertrophy and associated factors in a Thai population.

Electrocardiographic left ventricular hypertrophy (LVH) has been a bad prognostic factor for cardiovascular morbidity and mortality. However the prevalence and prognostic value of LVH are varied among nationalities and populations. Several factors have been shown to associate with LVH. Some factors are treatable such as hypertension. We prospectively studied the prevalence of LVH and associated factors in selected group of Thai population. The study population was 1,606 Shinawatra employees who were 30 year old or more. The prevalence of LVH was 13 per cent (210) among study population. Hypertension, lower body weight and male sex were significantly associated factors. In the subjects with LVH, the prevalence of hypertension was 25.6 per cent, male ratio was 5:1 and mean body weight was 57.7 kg, compare to 9.8 per cent prevalence of hypertension, 2:1 female ratio and mean body weight was 62.3 kg in the group without LVH.

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.

Are routine checkups necessary?: The Shinawatra's employee study.

The authors performed a survey in 3,615 Shinawatra employees aged 18-60 years to determine the abnormalities found with routine checkup. The annual checkup included: history taking. anthropometric measurement, physical examination, complete blood count, urine analysis, chest roentgenography, blood chemistry (fasting blood glucose, BUN, creatinine, uric acid, AST/ALT, cholesterol, triglyceride and HDL-cholesterol). The prevalence of abnormalities with management change detected by complete blood count, urine analysis was low and we did not recommend the routine use of complete blood count and urine analysis. The prevalence of hypertension was more common in males and the prevalence increased sharply after the age of 25 years in males and 40 years in females. The prevalence of abnormalities of BUN, creatinine (both males and females) and uric acid (in females) was very low. There was high prevalence of high AST/ALT which suggested hepatitis in our population, and the prevalence was more common in males beginning at a young age. Diabetes mellitus was more common in males especially after the age of 45 years. Chest roentgenography abnormalities were found in 9.4 per cent and the prevalence of abnormalities increased with age and was common after the age of 44 years. Most of the abnormalities found by chest roentgenography were pulmonary infiltration and cardiomegaly. The authors' findings did not recommend the routine use of complete blood count, urine analysis, fasting BUN and creatinine. We recommend routine blood pressure measurement in males aged 25 years or more and in females aged 40 years or more. We suggest routine blood cholesterol measurement in both sexes, blood triglyceride measurement in males aged 25 years or more and fasting blood sugar tests in males aged more than 44 years, chest roentgenography in males and females after the age of 45 years.

A 5-year prospective study of conventional risk factors of coronary artery disease in Shinawatra employees: a preliminary prevalence survey of 3,615 employees.

We conducted a prevalence survey of conventional risk factors of coronary artery disease in 3,615 Shinawatra employees and we planned to prospectively follow up this population to determine the impact of the risk factors in the development of coronary disease. The prevalence of hypertension, diabetes mellitus, hyperlipidemia, obesity, physical inactivity and smoking were 7.4 per cent, 1.4 per cent, 21.1 per cent, 13.9 per cent, 76.3 per cent and 16.3 per cent respectively. The awareness of hypertension, diabetes mellitus and hyperlipidemia were 42.2 per cent, 78 per cent and 32.9 per cent respectively. The prevalence of the risk factors was more common in males and increased with increasing age. Dependent variables which were associated with hypertension included: excessive weight; male sex; increasing age; hypercholesterolemia and diabetes mellitus. Variables which were associated with diabetes mellitus were hypertriglyceridemia, hypertension, male sex, increasing age and excessive weight.. Variables which were associated with hypercholesterolemia were hypertriglyceridemia, high HDL-cholesterol, increasing age, excessive weight and hematocrit level while overweight, hypercholesterolemia, low HDL-cholesterol, smoking, hematocrit level, low income and increasing age were associated with hypertriglyceridemia. Excessive weight was associated with hypertriglyceridemia, low HDL-Cholesterol, presence of hypertension, hypercholesterolemia, diabetes mellitus, increasing age and low education.

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.

The use of nonfluoroscopic catheter-based mapping system to perform radiofrequency ablation in complex ventricular tachycardia after cardiac surgery in congenital heart disease: a case report.

A nonfluoroscopic electroanatomical cardiac mapping system (CARTO) integrates anatomical and electrophysiological information to reconstruct a three-dimensional activation map. Information from the CARTO system helps to reveal the mechanism and perform successful ablation in scar re-entry ventricular tachycardia after cardiac surgery. Three-dimensional activation and propagation mapping was performed in a patient with ventricular tachycardia after surgical correction of a double outlet right ventricle. The ventricular tachycardia appeared in two morphologies and were refractory to antiarrhythmic medication including amiodarone. Both ventricular tachycardias were re-entered using the ventriculotomy scar but rotated in different directions. Successful radiofrequency ablation was performed by creating a line of conduction block from the pulmonic valve to the ventriculotomy scar using entrainment mapping and the ablation lesion tagging technique. The CARTO system is useful in mapping and guiding the ablation of complex ventricular tachycardia after surgical correction in congenital heart disease

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 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.