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We present a case of temporary guidewire pacing in a patient with Fontan anatomy during transcatheter aortic valve implantation. Temporary pacing was successfully achieved utilizing this method without complications. There is an increasing population of patients with complex congenital heart disease and expanding variety of transcatheter interventions. Due to limitations in vascular access and surgical anatomies, guidewire pacing may have a wide array of potential applications in pediatrics and the congenital heart disease population., (© 2019 Wiley Periodicals, Inc.)

Background: Successful ablation sites in Wolff-Parkinson-White syndrome (WPW) are characterized by short atrioventricular (AV) intervals. Approximately 15% of patients with WPW have adenosine-sensitive accessory pathways (APs). We sought to determine if local AV intervals of adenosine-sensitive APs are different from those of adenosine-insensitive APs in patients with WPW., Methods: Patients ≤21 years with WPW and adenosine-sensitive APs who underwent successful ablation over a 9-year period were included. Patients with WPW and adenosine-insensitive APs were matched by age and weight in a 1:2 case-control design. AP location, antegrade and retrograde conduction properties, supraventricular tachycardia (SVT) inducibility, local AV interval, interval from delta wave onset to local ventricular activation (del-V), and time to loss of preexcitation were reviewed., Results: Fourteen patients with adenosine-sensitive APs and 28 with adenosine-insensitive APs were included. Patients with adenosine-sensitive APs had minimum 1:1 antegrade AP conduction at a longer median paced cycle length (380, interquartile range [IQR] 295 to 585 ms vs 290, IQR 250 to 330 ms, P = 0.046), were less likely to have inducible SVT (35.7% vs 75.0%, P = 0.035), and had a longer median local AV interval (40.5, IQR 30.8 to 58.3 ms vs 32.0, IQR 29.3 to 37.8 ms, P = 0.029) when compared to those with adenosine-insensitive APs., Conclusion: Patients with WPW and adenosine-sensitive APs have 1:1 antegrade AP conduction at longer cycle lengths, lower likelihood of SVT induction, and longer local AV intervals when compared to those with adenosine-insensitive APs. In patients with WPW, it may be important to consider adenosine response when selecting appropriate ablation targets., (© 2017 Wiley Periodicals, Inc.)

Background: Borderline QTc is a common referral to the pediatric cardiology clinic. Evaluation is challenging due to significant overlap of normal and abnormal QTc ranges. We hypothesized that automated QT analysis on Holter could differentiate between patients with long QT syndrome (LQTS) and healthy controls., Methods: We conducted a retrospective review of 39 patients with known genotype-positive, phenotype-positive LQTS who underwent Holter monitoring between January 2010 and January 2016. They were compared 2:1 to age- and sex-matched controls. Automated QT analysis data were analyzed., Results: Significant differences were found in all automated QT and QTc fields, except minimum QTc interval (P = 0.57). Mean QTc interval (LQTS 479 ± 28 ms vs controls 429 ± 16 ms; P ≤ 0.001) and percent QTc intervals (%QTc) >450 ms (LQTS 80 ± 28% vs controls 14 ± 16%; P ≤ 0.001) were selected for further analysis. A receiver operating characteristic curve was generated for each variable demonstrating high area under the curve values of 0.9494 and 0.9540, respectively. Threshold values of ≥461 ms for mean QTc (sensitivity 79.49%, specificity 98.72%) and ≥65% of %QTc >450 ms (sensitivity 79.49%, specificity 98.72%) allowed highly specific discrimination between cohorts (false positive rate 1.09%). Similarly, thresholds of <434 ms (sensitivity 97.44, specificity 61.54) for mean QTc and <32% (sensitivity 89.74, specificity 87.18) for %QTc >450 ms resulted in highly sensitive discrimination (false negative rates 2.17% and 8.7%)., Conclusion: Holter monitor testing with automated QT analysis may be a useful tool to differentiate LQTS and control patients., (© 2017 Wiley Periodicals, Inc.)