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Background: Transcatheter closure of a secundum atrial septal defect (ASD) has become an effective method for surgical treatment. In this study, we evaluated the feasibility and accuracy of intracardiac echocardiography (ICE) for sizing ASDs compared with conventional methods., Methods: Between January 2004 and December 2006, 270 patients underwent transcatheter closure of secundum ASD by using septal occluders. For 142 patients, the procedure was guided by transesophageal echocardiography (TEE), and for 128 patients by ICE. We compared the maximal diameters of the ASDs obtained during angiocardiography, transthoracic echocardiography (TTE), ICE, and TEE with balloon-stretched sizes ascertained by using a sizing plate., Results: ASD diameters measured with the sizing plate were significantly correlated with those measured with ICE (r = 0.963), TEE (r = 0.912), angiography (r = 0.88), and TTE (r = 0.85). The predicted stretched diameter of the ASDs, i.e. (nonstretched diameter measured with ICE x 1.07) + 3.23 mm, agreed well with that measured by using a sizing plate (Ri = 0.974)., Conclusion: ASD diameters measured with ICE correlated with sizing-plate measurements better than those determined with TEE, angiography or TTE.

Background: Data detailing the age-related difference in the atrial substrate for formation of typical atrial flutter (AFL) are sparse., Objective: The purpose of this study was to characterize the difference in the right atrial substrate related to aging using noncontact mapping of the right atrium., Methods: A total of 54 patients (23 young [<60 years; 45 +/- 12 years] and 31 old [>or=60 years; 74 +/- 6 years]) with typical AFL who underwent three-dimensional noncontact mapping of typical AFL were enrolled in the study. The atrial substrate was characterized according to (1) regional wavefront activation mapping, (2) regional conduction velocity, and (3) regional voltage distribution by dynamic substrate mapping., Results: During activation mapping of the crista terminalis, two activation patterns were observed: (1) around the upper end of the crista terminalis (67%) and (2) through a gap in the crista terminalis. The presence of a crista terminalis gap was associated with a high incidence of induced atypical AFL/atrial fibrillation (P <.001). The conduction velocities of the medial cavotricuspid isthmus were slower in the old group than in the young group. In regional activation mapping of the AFL, the location of the slowest conduction shifted from the lateral cavotricuspid isthmus (71%) in the young group to the medial cavotricuspid isthmus (40%) in the old group. More cases with a low-voltage zone (

Background: This study investigated the electrophysiologic characteristics, atrial activation pattern, and effects of radiofrequency (RF) catheter ablation guided by noncontact mapping system in patients with focal atrial tachycardia (AT)., Methods and Results: In 13 patients with 14 focal ATs, noncontact mapping system was used to map and guide ablation of AT. AT origins were in the crista terminalis (n=8), right atrial (RA) free wall (n=3), Koch triangle (n=1), anterior portion of RA-inferior vena cava junction (n=1), and superior portion of tricuspid annulus (n=1); breakout sites were in the crista terminalis (n=5), RA free wall (n=5), middle cavotricuspid isthmus (n=2), and RA-superior vena cava junction (n=2). ATs arose from the focal origins (11 ATs inside or at the border of low-voltage zone), with preferential conduction, breakout, and spread to the whole atrium. After applications of RF energy on the earliest activation site or the proximal portion of preferential conduction from AT origin, 13 ATs were eliminated without complication. During the follow-up period (8+/-5 months), 11 (91.7%) of the 12 patients with successful ablation were free of focal ATs., Conclusions: Focal AT originates from a small area and spreads out to the whole atrium through a preferential conduction. Application of RF energy guided by noncontact mapping system was effective and safe in eliminating focal AT.

Background: Obesity impairs performance in most athletic events. The prevalence of obesity in Taiwan has increased over the past decades. It is important to understand any alterations in cardiopulmonary responses to exercise in obese children. The purpose of this study is to evaluate the cardiorespiratory response to graded treadmill exercise testing protocol in obese children., Methods: Twenty obese and 10 control children between 8 to 12 years of age were recruited among patients at Pediatric Clinics. The treadmill was set at a grade of 10% to perform continuous treadmill walking. Measures of cardiopulmonary responses were recorded. Height, weight and body mass index were determined before testing., Results: Cardiopulmonary responses including heart rate (HR), systolic pressure (SP), rate-pressure product (RPP) and forced vital capacity (FVC) were significantly different between obese children and normal children during and after exercise. The correlations of cardiopulmonary function to age, sex, height, body weight, triceps and biceps skinfold thickness were assessed, and a significant correlation was found between HR and age (r = 0.5, p < 0.05), as well as biceps skinfold thickness (r = 0.5, p < 0.05). There was also a good correlation between predicted values of FVC and age (r = -0.5, p < 0.05). The HR (r = 0.79, p < 0.05) was in correlation with tricep skinfold thickness in normal healthy children., Conclusions: In conclusion, there appears to show a relatively less efficient cardiopulmonary response in obese children. Regular exercise that improves fitness and body composition should have a favorable effect on obese children.