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Mechanical circulatory support options for infants and children are very limited in the United States. Existing circulatory support systems have proven successful for short-term pediatric assist, but are not completely successful as a bridge-to-transplant or bridge-to-recovery. To address this substantial need for alternative pediatric mechanical assist, we are developing a novel, magnetically levitated, axial flow pediatric ventricular assist device (PVAD) intended for longer-term ventricular support. Three major numerical design and optimization phases have been completed. A prototype was built based on the latest numerical design (PVAD3) and hydraulically tested in a flow loop. The plastic PVAD prototype delivered 0.5-4 lpm, generating pressure rises of 50-115 mm Hg for operating speeds of 6,000-9,000 rpm. The experimental testing data and the numerical predictions correlated well. The error between these sets of data was found to be generally 7.8% with a maximum deviation of 24% at higher flow rates. The axial fluid forces for the numerical simulations ranged from 0.5 to 1 N and deviated from the experimental results by generally 8.5% with a maximum deviation of 12% at higher flow rates. These hydraulic results demonstrate the excellent performance of the PVAD3 and illustrate the achievement of the design objectives.

This study tested the hypothesis that pediatric patients who develop chylothorax (CTX) after surgery for congenital heart disease (CHD) have an elevated incidence and risk profile for central venous thrombosis (CVT). We evaluated 30 patients who developed CTX after surgery for CHD. All but one CTX patient were surgery-, anatomy-, and age-matched with two controls (NON-CTX) to compare their relative risk and incidence of CVT. Using conditional logistic regression analyses, CTX development was associated with significantly longer ventilator dependence (14.8 +/- 10.9 vs. 6.1 +/- 5.9 days, p = 0.003) and a non-significant trend towards more days of central venous catheters (CVC) (19.1 +/- 16.6 vs. 12.2 +/- 10.0 days; p = 0.16) when comparing the period prior to CTX development with the entire hospitalization in NON-CTX patients. CTX development was associated with a significantly elevated mortality risk (Odds Ratio 6.2, 95% CI 1.3-30.9). Minimum and mean daily central venous pressures were significantly higher in the CTX group. Post operative need for extracorporeal membrane oxygenation conferred an increased risk of CTX development in this sample of patients (Odds Ratio 9.9, 95% CI 2.2-44.8). Incidence of documented CVT was 26.7% in the CTX group versus 5.1% in the NON-CTX group. Prospective screening for CVT risk and formation, combined with early removal of CVC may help reduce the incidence of CTX.

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Vascular rings can be challenging to diagnose because they can contain atretic portions not detectable with current imaging modalities. In these cases, where the compressed airway and esophagus are not encircled by patent, opacified vessels, there are useful secondary signs that should be considered and should raise suspicion for the presence of a vascular ring. These signs include a double aortic arch, the four-vessel sign, the distorted subclavian artery sign, a diverticulum of Kommerell, a ductal diverticulum contralateral to the aortic arch, and a descending aorta contralateral to the arch or circumflex aorta. If none of these findings is present, a ring can be excluded with confidence.

By 6 years of age, heart failure developed in nearly 15% of children after the Norwood procedure. Although transplant listing was common, many patients died from heart failure before receiving a transplant or without being listed. Shunt type did not impact the risk of developing heart failure.

The Virginia Artificial Heart Institute continues to design and develop an axial-flow pediatric ventricular assist device (PVAD) for infants and children in the United States. Our research team has created a database to track potential PVAD candidates at the University of Virginia Children's Hospital. The findings of this database aided with need assessment and design optimization of the PVAD. A numerical analysis of the optimized PVAD1 design (PVAD2 model) was also completed using computational fluid dynamics (CFD) to predict pressure-flow performance, fluid force estimations, and blood damage levels in the flow domain. Based on the PVAD2 model and after alterations to accommodate manufacturing, a plastic prototype for experimental flow testing was constructed via rapid prototyping techniques or stereolithography. CFD predictions demonstrated a pressure rise range of 36-118 mm Hg and axial fluid forces of 0.8-1.7 N for flows of 0.5-3 l/min over 7000-9000 rpm. Blood damage indices per CFD ranged from 0.24% to 0.35% for 200 massless and inert particles analyzed. Approximately 187 (93.5%) of the particles took less than 0.14 seconds to travel completely through the PVAD. The mean residence time was 0.105 seconds with a maximum time of 0.224 seconds. Additionally, in a water/glycerin blood analog solution, the plastic prototype produced pressure rises of 20-160 mm Hg for rotational speeds of 5960 +/- 18 rpm to 9975 +/- 31 rpm over flows from 0.5 to 4.5 l/min. The numerical results for the PVAD2 and the prototype hydraulic testing indicate an acceptable design for the pump, represent a significant step in the development phase of this device, and encourage manufacturing of a magnetically levitated prototype for animal experiments.