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Pediatric ECG standards have been defined without echocardiographic confirmation of normal anatomy. The Pediatric Heart Network Normal Echocardiogram Z-score Project provides a racially diverse group of healthy children with normal echocardiograms. We hypothesized that ECG and echocardiographic measures of left ventricular (LV) dimensions are sufficiently correlated in healthy children to imply a clinically meaningful relationship. This was a secondary analysis of a previously described cohort including 2170 digital ECGs. The relationship between 6 ECG measures associated with LV size were analyzed with LV Mass (LVMass-z) and left ventricular end-diastolic volume (LVEDV-z) along with 11 additional parameters. Pearson or Spearman correlations were calculated for the 78 ECG-echocardiographic pairs with regression analyses assessing the variance in ECG measures explained by variation in LV dimensions and demographic variables. ECG/echocardiographic measurement correlations were significant and concordant in 41/78 (53%), though many were significant and discordant (13/78). Of the 6 ECG parameters, 5 correlated in the clinically predicted direction for LV Mass-z and LVEDV-z. Even when statistically significant, correlations were weak (0.05-0.24). R 2 was higher for demographic variables than for echocardiographic measures or body surface area in all pairs, but remained weak (R 2  ≤ 0.17). In a large cohort of healthy children, there was a positive association between echocardiographic measures of LV size and ECG measures of LVH. These correlations were weak and dependent on factors other than echocardiographic or patient derived variables. Thus, our data support deemphasizing the use of solitary, traditional measurement-based ECG markers traditionally thought to be characteristic of LVH as standalone indications for further cardiac evaluation of LVH in children and adolescents., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Heparin is used to decrease the risk of thromboembolic complications during electrophysiology studies (EPS); however, there is wide practice variation and minimal evidence to guide heparin dosing, particularly in pediatric patients. This study retrospectively analyzed heparin dosing and response, measured via activated clotting time (ACT), in patients undergoing EPS and used these data (pre-protocol cohort, n = 40), as well as guidance from available literature to implement a standardized heparin protocol (phase 1, n = 43). We utilized quality improvement methodology to refine this protocol (phase 2, n = 40) to improve therapeutic heparin response. Prior to the protocol, patients achieved therapeutic ACT levels (250-350 s) only 35% of the time which improved to 60% during phase 1 (p < 0.05) and to 73% during phase 2 (p < 0.001 compared to pre-protocol). There were no thromboses or significant adverse events in any group. These results demonstrate the effectiveness of a standardized heparin protocol in achieving effective antithrombotic therapy during left-sided pediatric EPS.

This study aimed to examine practice patterns in the inpatient medical treatment of newborns and infants with supraventricular tachycardia (SVT) using the Pediatric Health Information System (PHIS) database, a large, multi-institutional administrative database. A retrospective examination of pediatric hospital discharge data was performed during the study period from January 2003 to September 2008. Data were extracted from the index hospitalization of all individuals younger than 1 year with the principal discharge diagnosis of SVT. Those with coexisting congenital or acquired structural heart disease were excluded from the study. The analysis included 171 patients. No deaths occurred, and 95 % of the infants were discharged to home. More than half (53 %) of the patients spent a portion of their hospital stay in an intensive care unit (ICU) setting. Multidrug therapy was common, with 45 % of the patients receiving two or more antiarrhythmic agents on the day of discharge. The five most commonly used antiarrhythmic drugs, in order of decreasing frequency of use, were propranolol, digoxin, amiodarone, flecainide, and sotalol. The median hospital stay for the group was 4 days, and this value increased as a function of the number of antiarrhythmic drugs used (median, 7 days for three or more agents) and the need for intensive care (median, 6 days). The information provided in this study helps to define common practice patterns and should allow caregivers to provide meaningful expectations to families regarding their potential treatment course and to anticipate the hospital length of stay.

The development of tachycardia-induced cardiomyopathy (TIC) is related to the rate and duration of supraventricular tachycardia (SVT). Infants may be more susceptible to TIC because early symptoms might be unrecognized. Extracorporeal membrane oxygenation (ECMO) may improve outcome in patients with SVT and TIC; however, clinical predictors of infants who require ECMO support have not been determined. The purpose of this study was to identify predictors of the need for ECMO in infants with SVT and TIC. Sixteen infants <6 months of age who experienced resolution of TIC following control of arrhythmia were identified. Three patients (19%) required ECMO support. Comparisons were made between patients who required ECMO and those who did not. The groups were similar with respect to age at presentation, type of SVT, rate of SVT, and degree of ventricular dysfunction. However, patients requiring ECMO had increased median M-mode-derived left ventricular end diastolic dimension (LVED) z-score when compared to the medically managed patents (+2.8 vs. 0.0, P = 0.009). No patient in the medically managed group had an LVED z-score >2.3. Infants presenting with SVT and TIC with LVED z-score >2 are at increased risk for requiring ECMO support and early use of ECMO should be considered.

Left ventricular noncompaction (LVNC) is an uncommon disorder that has recently been recognized as a distinct cardiomyopathy. LVNC is thought to result from an arrest in the normal process of myocardial compaction. The association of Wolff-Parkinson-White with noncompaction of the left ventricle is well recognized. Sinus bradycardia has also been associated with LVNC, although less frequently than that of Wolff-Parkinson-White. We report an infant with LVNC, Wolff-Parkinson-White, and progressive sinus bradycardia who had a myocardial vascular abnormality in the region of the sinus node evident on autopsy. We propose that the progressive nature of the conduction system abnormality was as a result of abnormal angiogenesis.