Novel application of the Diabolo technique to restrict pulmonary blood flow in a single ventricle patient with a right ventricle to pulmonary artery conduit.

Balancing pulmonary and systemic circulations in single ventricle patients with a conduit after Stage 1 palliation is challenging. A transcatheter intervention for excessive pulmonary blood flow would provide benefit. We report a case of a critically ill single ventricle patient with symptoms of excessive pulmonary blood flow after Stage 1 despite maximal medical therapy. The patient underwent percutaneous intraluminal downsizing of the right ventricle to pulmonary artery conduit using a novel application of the Diabolo-covered stent technique, with subsequent clinical improvement. A second catheterization was performed during the interstage period with successful dilation of the stent to achieve appropriate saturations. The Diabolo technique can be successfully employed in this population to restrict pulmonary blood flow and has the advantage of being adjusted during placement and in subsequent interventions.

Patent ductus arteriosus and coarctation of the aorta in association with PRDM6 variants.

Patent ductus arteriosus (PDA) and coarctation of the aorta (CoA) are relatively common congenital heart defects. Pathogenic variants in PRDM6, which encodes a smooth-muscle-cell-specific transcription factor, have now been etiologically associated with non-syndromic PDA. We present three patients with PDA and CoA found to harbor PRDM6 variants, including a novel, likely-pathogenic variant.

Cardiopulmonary Exercise Testing in Pediatric Patients With Hypertrophic Cardiomyopathy.

Background: Exercise stress testing (EST) in pediatric hypertrophic cardiomyopathy (HCM) patients has not well described in a large heterogenous cohort. Objectives: The objective of the study was to determine the clinical utility of EST in pediatric HCM. Methods: This was a retrospective single-center analysis of HCM patients younger than 21 years who had EST between January 1, 2000, and January 1, 2019. Clinical, demographic characteristics, and EST data were analyzed, using the last EST during the study or prior to the event in subjects with a primary outcome. The primary composite endpoint included cardiac death, transplant, or arrhythmia requiring implantable cardioverter-defibrillator placement. Outcome analysis was performed using Cox proportional hazard modeling. Results: The study cohort included 140 patients, 52% with a recognized genetic variant. There were 2 tests aborted due to safety concerns (ST-segment changes, ventricular ectopy). The median age at first EST was 13.6 years. Ninety percent of patients were tested using cycle ergometry, and 44% were on a beta-blocker. The median peak oxygen consumption was 37.1 mL/kg/min (IQR: 12.5 mL/kg/min) or 81.2% predicted, the mean anaerobic threshold was 21.8 Ml (IQR: 8.3 mL), and the median peak power was 2.6 ± 1.1 W/kg or 73.7% predicted. Ectopy during EST was seen in 44% of patients, and 8% had an abnormal blood pressure response to exercise. The endpoint was reached in 12 patients. The presence of any degree of ectopy was a predictor of the composite endpoint (hazard ratio: 5.8; 95% CI: 1.3-26.7). Conclusions: EST is clinically useful in select pediatric patients with HCM. Ectopy on EST is a risk factor for cardiac death, cardiac transplant, and arrhythmias requiring implantable cardioverter-defibrillator.

Transfusional Iron Overload in a Cohort of Children with Sickle Cell Disease: Impact of Magnetic Resonance Imaging, Transfusion Method, and Chelation.

BACKGROUND: Transfusions prevent a number of complications of sickle cell disease (SCD), but cause inevitable iron loading. With magnetic resonance imaging (MRI), liver iron can be monitored noninvasively. Erythrocytapheresis can limit iron loading and oral chelation provides a more tolerable alternative to subcutaneous administration. The impact of these factors on control of iron burden in SCD has not been well studied. PROCEDURE: Iron monitoring practices, chelation use, and transfusion methods were assessed in our cohort of pediatric patients with SCD receiving chronic transfusion. The impact of these factors on iron burden was assessed. RESULTS: Among 84 subjects, the proportion that underwent appropriate liver iron concentration (LIC) assessment rose from 21% before to 81% after implementation of R2-MRI in 2006. Among subjects with at least two R2-MRI examinations, median LIC improved (13.2-7.9 mg/g dw, P = 0.027) from initial to final study. Most (67.9%) subjects initially received simple transfusions and subsequently transitioned to erythrocytapheresis. After switching, LIC improved from 13.1 to 4.3 mg/g dw (P < 0.001) after a median of 2.7 years and ferritin improved (2,471-392 ng/ml, P < 0.001) after a median of 4.2 years. Final serum ferritin and LIC correlated negatively with the proportion of transfusions administered by erythrocytapheresis and chelation adherence. CONCLUSIONS: Routine liver R2-MRI should be performed in individuals with SCD who receive chronic red cell transfusions. Adherence with chelation should be assessed regularly and erythrocytapheresis utilized when feasible to minimize iron loading or reduce iron stores accumulated during periods of simple transfusion.