Radiofrequency ablation in children and adolescents: results in 154 consecutive patients

AIMS: The experience of using radiofrequency ablation (RFA) for the treatment of arrhythmias in children and adolescents is still limited. This study aimed to review the most recent results of RF ablation in children and adolescents in a highly experienced centre with access to both conventional techniques and non-fluoroscopic electroanatomic mapping (CARTO). METHODS AND RESULTS: A total of 154 consecutive patients younger than 19 years treated with RFA during the period 2000-04 were included. Numbers (%) or median (quartiles) are reported. Age was 15 (12-17) years, 70 (45%) were males. Five patients (3%) had congenital heart disease. RFA was successful in 147/154 patients (95%). Arrhythmia recurrence occurred in 11 patients (7%). Procedure time was 55 (35-90) min and fluoroscopy time was 8.8 (4-19) min. Number of RF applications was 4 (2-10) and number of RF applications >20 s was 2 (1-7). One patient (0.7%) had complicating high-grade atrioventricular block. CARTO was used in 18 RF ablation procedures (11%) performed in 15 patients. CONCLUSION: RF ablation can be undertaken in children and adolescents with a high success rate, few recurrences and complications, very short procedure times, and acceptable fluoroscopy times. Non-fluoroscopic electroanatomic mapping is helpful in selected patients.

Electroanatomic reconstruction of the left atrium, pulmonary veins, and esophagus compared with the "true anatomy" on multislice computed tomography in patients undergoing catheter ablation of atrial fibrillation

BACKGROUND: Current concepts of catheter ablation for atrial fibrillation (AF) commonly use three-dimensional (3D) reconstructions of the left atrium (LA) for orientation, catheter navigation, and ablation line placement. OBJECTIVES: The purpose of this study was to compare the 3D electroanatomic reconstruction (Carto) of the LA, pulmonary veins (PVs), and esophagus with the true anatomy displayed on multislice computed tomography (CT). METHODS: In this prospective study, 100 patients undergoing AF catheter ablation underwent contrast-enhanced spiral CT scan with barium swallow and subsequent multiplanar and 3D reconstructions. Using Carto, circumferential plus linear LA lesions were placed. The esophagus was tagged and integrated into the Carto map. RESULTS: Compared with the true anatomy on CT, the electroanatomic reconstruction accurately displayed the true distance between the lower PVs; the distances between left upper PV, left lower PV, right lower PV, and center of the esophagus; the longitudinal diameter of the encircling line around the funnel of the left PVs; and the length of the mitral isthmus line. Only the distances between the upper PVs, the distance between the right upper PV and esophagus, and the diameter of the right encircling line were significantly shorter on the electroanatomic reconstructions. Furthermore, electroanatomic tagging of the esophagus reliably visualized the true anatomic relationship to the LA. On multiple tagging and repeated CT scans, the LA and esophagus showed a stable anatomic relationship, without relevant sideward shifting of the esophagus. CONCLUSION: Electroanatomic reconstruction can display with high accuracy the true 3D anatomy of the LA and PVs in most of the regions of interest for AF catheter ablation. In addition, Carto was able to visualize the true anatomic relationship between the esophagus and LA. Both structures showed a stable anatomic relationship on Carto and CT without relevant sideward shifting of the esophagus.

Is alcohol ablation of the septum associated with recurrent tachyarrhythmias?

QUESTIONS UNDER STUDY: Alcohol ablation (AA) of the septum has been introduced as new therapy in hypertrophic cardiomyopathy (HCM). It was feared that iatrogenic myocardial infarction due to AA may induce re-entry tachyarrhythmias and increase sudden cardiac death. METHODS AND RESULTS: Twenty-four patients (mean age 52 years) underwent successful AA. Clinical follow-up (FU) ranged from 0.3 to 0.7 years (mean 2.8). One patient died (suicide) 4 years after AA. Left ventricular (LV) outflow gradient (peak-to-peak) decreased (median) after AA from 43 (IQR 25 to 4) mmHg to 1 (IQR 0 to 12) mmHg (rest) (p <0.001) and from 130 (IQR 75 to 165) mmHg to 13 (IQR 0 to 31) mmHg (postextrasystolic) (p <0.001). Transient AV block occurred in 22% (5/24) necessitating temporary pacing. A permanent pacemaker was implanted in 4% (1/24). NYHA-class was 2.5 (IQR 2.0 to 3.0) before and 1.5 (IQR 1.3 to 2.0) (p <0.001) after AA. During FU, 2 pacemakers were implanted due to bradycardia (no AV block). A right bundle branch block was found in 13% (2/24) before and 46 % (11/24) after AA (p = 0.003). Non-sustained ventricular tachycardia (NSVT) was observed in 13% (2/16) before and 22% (5/23) (p = 0.46) after AA. Two patients required ICD implantation. CONCLUSIONS: Long-term FU is excellent in HCM after AA. The pressure gradient drops below 25 mm Hg in 95% (23/24) of all patients. Transient AV block occurs in 22% (5/24), but permanent pacemaker implantation is rarely needed (13%, 2/24). Severe NSVT occurs in 13% (2/16) before and 22% (5/23) after AA but ICD implantation is only occasionally required.

His-Purkinje system re-entry in patients with clustering ventricular tachycardia episodes

AIMS: Multiple arrhythmia re-inductions were recently shown in His-Purkinje system (HPS) ventricular tachycardia (VT). We hypothesized that HPS VT was a frequent mechanism of repetitive or incessant VT and assessed diagnostic criteria to select patients likely to have HPS VT. METHODS AND RESULTS: Consecutive patients with clustering VT episodes (>3 sustained monomorphic VT within 2 weeks) were included in the analysis. HPS VT was considered plausible in patients with (i) impaired left ventricular function associated with dilated cardiomyopathy or valvular heart disease; or (ii) ECG during VT similar to sinus rhythm QRS or to bundle-branch block QRS. HPS VT was plausible in 12 of 48 patients and HPS VT was demonstrated in 6 of 12 patients (50%, or 13% of the whole study group). Median VT cycle length was 318 ms (250-550). Catheter ablation was successful in all six patients. CONCLUSION: His-Purkinje system VT is found in a significant number of patients with repetitive or incessant VT episodes, and in a large proportion of patients with predefined clinical or electrocardiographic characteristics. Since it is easily amenable to catheter ablation, our data support the screening of all patients with repetitive VT in this regard and an invasive approach in a selected group of patients.

Transseptal puncture for catheter ablation of atrial fibrillation after device closure of patent foramen ovale

The technique of transseptal puncture for catheter ablation of atrial fibrillation after percutaneous closure of a foramen ovale with the Amplatzer Occluder is demonstrated based on 2 representative cases.

The Application of Laser-Ablation Split-Stream ICP Petrochronology to Metamorphic Studies

Discussion of a new, innovative method for dating rocks, called laser ablation split stream (LASS) petrochronology, which is an in situ method that couples geochronological and geochemical data of minerals that remain in the rock matrix. The talk focuses on the application of this technique with U-Th-Pb dating of the phosphate minerals monazite and xenotine in metamorphic rocks. Examples from the Ruby Range in southwestern Montana and metamorphic core complexes in the northern Idaho panhandle will be explored.