Radiation dose during catheter ablation in children using a low fluoroscopy frame rate.

BACKGROUND: Catheter ablation (CA) in children using fluoroscopy carries risks inherent to ionizing radiation exposure. AIMS: The objective of this study was to demonstrate the feasibility of using low frames rate during ablation in children to maximally decrease radiation dose. METHODS: Hundred sixty eight successive patients<18 years of age undergoing CA performed under a 3.75 frames/second rate were retrospectively included. Demographics, procedural and dosimetry data were analysed. The effective dose (ED) was evaluated in a subgroup of 14 patients. RESULTS: Median age and weight were 15 years and 54kg, 72% had WPW, 10% AV node reentrant tachycardia, 10% ventricular tachycardia (atrial tachycardia, flutter and atrial fibrillation for the other cases). Acute success was achieved in 98.5% without any complication. Median procedure and fluoroscopy duration were 120 and 16minutes. Median Dose Area Product (DAP) and Air Kerma were 2.46Gy.cm2 and 18 mGy respectively (2Gy.cm2 and 15 mGy for WPW ablation). A significant reduction of median DAP was noted over the years for WPW, from 3.1Gy.cm2 in 2011 to 1.4 in 2019. Median estimated ED was 0.19 mSv (0.03 to 1.64), falling into the range of yearly normal natural irradiation or caused by leasure or professional activity. CONCLUSION: Low frame rate fluoroscopy is a highly effective and safe approach in decreasing radiation exposure during CA in children without altering the success rate of the procedure. ED is low, similar to natural/leisure irradiation. This approach can be considered a good alternative to 3D-based procedures in terms of efficiency and radiation issues, at least for WPW ablations.

Lexical learning of the English language: a PET study in healthy French subjects.

To investigate the neural correlates of word learning in adults, 10 right-handed French subjects who had learned English without mastering it performed an English and a French naming task during two PET sessions, one before (PET1) and the second after (PET2) a 4-week lexical training in English. Behavioral performance was collected during the two PET exams and 2 months after (T3). At T2, performance on English naming increased in all subjects; this improvement persisted at T3, with no correlation between English performance at T2 and T3. Cerebral activation during French naming mainly showed a left frontal temporal network. The pattern specifically associated with English lexical learning included, in addition to the anterior cingulate cortex involved in attentional processing and BAs 4/6 reflecting speech output, the right cerebellum and the left insular cortex that are linked to speech gesture learning, and the right medial temporal regions, likely to reflect the involvement of episodic memory during verbal learning. Correlations between English T2/T1 performance and English T2/T1 rCBF changes reinforced the hypothesis of intervention of episodic memory since they interested right frontal, hippocampal, and lateral temporal regions. 'Predictive' correlations between English T3/T2 performance and English T2/T1 rCBF changes showed, in good reminders, increased activities in the left posterior superior temporal sulcus and middle temporal cortex probably related to efficient semantic storage of learned words.