Preventing the risk of coronary injury in posteroseptal accessory pathway ablation in children: different strategies and advantages of fluoroscopy integrated 3D-mapping system (CARTO-UNIVU™).

PURPOSE: To evaluate various strategies in order to minimize the risk of coronary injury during posteroseptal accessory pathways ablation in children. METHODS: We retrospectively reviewed 68 posteroseptal accessory pathways ablation procedures (20 decremental and 48 typical accessory pathways) performed in 62 pediatric patients at our institution between July 2009 and December 2016. Only posteroseptal accessory pathways targeted near or within the coronary sinus were included and ablation was mostly performed using irrigated tip radiofrequency. RESULTS: Median patient age was 11 years with a median body weight of 39 kg. Thirty patients underwent a coronary angiogram, 21 were coupled to the 3D navigation system CARTO-UNIVU™. The coronary angiogram showed a distance of less than 5 mm between the coronary artery and the ablation site in 40% of our cases; 3 patients had a coronary injury related to RF ablation, 6 patients were switched for cryoablation, 3 patients received limited RF energy (20 W). There were no demographic data predicting the proximity of the coronary artery to the ablation site. CONCLUSION: Ablation of posteroseptal accessory pathways specifically in children carries a risk of coronary artery injury which is probably underestimated. The use of merged 3D images and coronary angiograms, the reduction of RF energy or the switch to cryoablation are possible alternatives to limit the risk of coronary injury.

Modeling of Amiodarone Effect on Heart Rate Control in Critically Ill Patients with Atrial Tachyarrhythmias.

AIMS: Amiodarone is the gold-standard medication to control heart rate in critically ill patients with atrial tachyarrhythmias (ATs); however, effective doses and covariates influencing its efficacy remain unknown. We therefore performed pharmacodynamic modeling of heart rate reduction induced by amiodarone in these patients. METHODS AND RESULTS: This observational study included 80 consecutive severely ill patients receiving amiodarone to treat ATs. A total of 1348 time-heart rate observations with 361 amiodarone dose administrations were analyzed during a period of up to 6 days after hospital treatment initiation using a nonlinear mixed-effect model. Pretreatment with amiodarone before intensive care administration, paroxysmal versus persistent AT, catecholamine infusion, and fluid and magnesium loading were among the covariates assessed in the model. In case of paroxysmal AT in a patient not pretreated with amiodarone, a 300 mg intravenous loading dose combined with an 800 mg oral dose on the first day, followed by 800 mg/day orally for 4 days was effective in achieving a heart rate between 80 and 115 bpm within the first day, and to maintain it during the next 4 days. Corresponding doses were twice as high in patients with persistent AT. Use of intravenous magnesium (p < 0.02) and fluid loading (p < 0.02) was associated with an earlier and greater heart rate decrease, while use of dobutamine had an opposite influence (p < 0.05). CONCLUSIONS: In critically ill patients with AT, the dose of amiodarone required to control heart rate is influenced by the type of AT and by other easily measurable conditions which may allow better individualization of amiodarone dosing.