Mary Krolikowski

INCLUDING AORTIC VALVE MORPHOLOGY IN COMPUTATIONAL FLUID DYNAMICS SIMULATIONS: INITIAL FINDINGS AND APPLICATION TO AORTIC COARCTATION

Computational fluid dynamics (CFD) simulations quantifying thoracic aortic flow patterns have not included disturbances from the aortic valve (AoV). 80% of patients with aortic coarctation (CoA) have a bicuspid aortic valve (BAV) which may cause adverse flow patterns contributing to morbidity. Our objectives were to develop a method to account for the AoV in CFD simulations, and quantify its impact on local hemodynamics. The method developed facilitates segmentation of the AoV, spatiotemporal interpolation of segments, and anatomic positioning of segments at the CFD model inlet. The AoV was included in CFD model examples of a normal (tricuspid AoV) and a post-surgical CoA patient (BAV). Velocity, turbulent kinetic energy (TKE), time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI) results were compared to equivalent simulations using a plug inlet profile. The plug inlet greatly underestimated TKE for both examples. TAWSS differences extended throughout the thoracic aorta for the CoA BAV, but were limited to the arch for the normal example. OSI differences existed mainly in the ascending aorta for both cases. The impact of AoV can now be included with CFD simulations to identify regions of deleterious hemodynamics thereby advancing simulations of the thoracic aorta one step closer to reality.

Internal working models of parenting: Motivations of parents of infants with a congenital heart defect

Drawing on attachment-caregiving theory, we interviewed parents of 24 infants with a complex congenital heart defect (CCHD) about parenting motivations through the first year. Using directed content analysis, 8 categories of motivations, focused either on the baby, the parent-infant relationship, family, self, or tasks were identified at 1, 4 or 6, and 12 months. A matrix of motivations by parent showed family and infant age variations. Motivations illustrated for 5 parents at 1 month suggest that specification of expectations and intentions and clustering of motivations mentioned by a parent would advance study of linkages of parenting internal working models with parenting action.

Caregiving motivations and developmentally prompted transition for mothers of prematurely born infants.

Parenting transition is a process prompted by infant developmental changes and may be defined by motivations for caregiving and the goals they indicate. Qualitative exploration of neonatal and 1-year feeding experience of 22 mothers of very-low-birth-weight infants revealed 3 types of caregiving-related motivations—nurturing, relating, and shaping quality of life. The clusters of motivations differed between ages and across mothers, suggesting transition in parenting reflective of both infant development and maternal goals. Study with a larger sample is needed to examine change in caregiving motivations and their function in characterizing parenting transitions.

Utility of speckle tracking echocardiography in measuring systemic right ventricular systolic function for patients with d-transposition of the great arteries status post atrial switch procedure: a comparison with cardiac magnetic resonance imaging

Background Patients with d-transposition of the great arteries (D-TGA), status post atrial switch, are at risk for developing systemic right ventricular (RV) dysfunction. Echocardiographic (Echo) assessment of RV function is subjective because complex RV geometry does not allow accurate determination of ejection fraction (EF). RVEF measured by cardiac magnetic resonance imaging (MRI) is the gold standard for quantitative assessment of systemic RV function. New Echo measures of ventricular deformation allow for quantitative assessment of RV function. The primary aim was to explore the correlation of global peak longitudinal strain (GPLS) of the systemic RV with MRI RVEF for patients with D-TGA status post atrial switch. The secondary aim was to characterize MRI and clinical findings in this population.

The Impact of Cardiac Motion on Aortic Valve Flow Used in Computational Simulations of the Thoracic Aorta.

Advancements in image-based computational modeling are producing increasingly more realistic representations of vasculature and hemodynamics, but so far have not compensated for cardiac motion when imposing inflow boundary conditions. The effect of cardiac motion on aortic flow is important when assessing sequelae in this region including coarctation of the aorta (CoA) or regurgitant fraction. The objective of this investigation was to develop a method to assess and correct for the influence of cardiac motion on blood flow measurements through the aortic valve (AoV) and to determine its impact on patient-specific local hemodynamics quantified by computational fluid dynamics (CFD). A motion-compensated inflow waveform was imposed into the CFD model of a patient with repaired CoA that accounted for the distance traveled by the basal plane during the cardiac cycle. Time-averaged wall shear stress (TAWSS) and turbulent kinetic energy (TKE) values were compared with CFD results of the same patient using the original waveform. Cardiac motion resulted in underestimation of flow during systole and overestimation during diastole. Influences of inflow waveforms on TAWSS were greatest along the outer wall of the ascending aorta (AscAo) (∼30 dyn/cm2). Differences in TAWSS were more pronounced than those from the model creation or mesh dependence aspects of CFD. TKE was slightly higher for the motion-compensated waveform throughout the aortic arch. These results suggest that accounting for cardiac motion when quantifying blood flow through the AoV can lead to different conclusions for hemodynamic indices, which may be important if these results are ultimately used to predict patient outcomes.

Cardiac magnetic resonance imaging can detect early vascular changes in children with type 1 diabetes (T1DM)

Adult studies have shown that cardiac magnetic resonance (CMR) can image vascular changes including altered aortic compliance and early plaque which correlates well with Framingham risk score and endothelial function. Impaired endothelial function, measured with brachial artery reactivity testing, is recognized as an early and modulating process in the pathophysiology of atherosclerotic plaque development. No CMR imaging studies of early atherosclerosis and vascular health exist in diabetic pediatric populations. This prospective pilot CMR proof of concept study hypothesized that children with T1DM will have thoracic aortic wall characteristics, as well as CMR-derived aortic computational fluid dynamic (CFD) models, different from age-matched control subjects. Furthermore, a positive correlation was sought between key CMR data and brachial artery reactivity measures, as well as cardiac venous biomarkers in T1DM. 7 control and 8 T1DM pediatric subjects had same-day fasting CMR scan, brachial artery testing, and venous blood draw (for lipid panel, HgbA1c, glucose, high sensitivity c-reactive protein (hs-cRP), fibrinogen, and homocysteine). Enrolled T1DM and control subjects were similar: age (14.5 ±1.7 versus (vs.) 15.2 ± 2.7 years), sex (4 male and 4 female T1DM vs. 5 male and 2 female controls), weight (55.7 ± 14.8 vs. 67.6 ± 23.5 kg), body mass index (20.8 ± 4.3 vs. 23.1 ± 5.7 kg/m2) and systolic blood pressure (113 ± 11.4 vs. 116 ± 8.8). They had no significant differences in lipid values, fibrinogen, or hs-cRP, but did differ with regard to glucose (182.1 ± 100.8 vs. 85.4 ± 5.7, p < 0.02), HgbA1c (9.0 ± 2.2 vs. 5.2 ± 0.3, p < 0.001), and homocysteine (4.3 ± 0.6 vs. 5.7 ± 1.0, p < 0.04). While brachial artery reactivity did not change with age, CMR determined ascending aortic (AAo) compliance decreased with increasing age in T1DM (R2 = 0.54, p < 0.09), but not for controls. In T1DM, CMR determined ascending aortic (AAo) compliance declined, as hs-cRP increased (R2 = 0.66, p < 0.05).No other significant correlations existed between AAo compliance and venous biomarkers. Preliminary qualitative analyses of aortic CFD models show different patterns of aortic wall shear stress and oscillatory shear index (OSI) for T1DM versus age-matched control pediatric subjects (Figure ​(Figure1).1). In conclusion, this pilot CMR study of T1DM and control pediatric subjects illustrates that early differences in vascular characteristics can be detected by MRI and correlate with age and with select venous biomarkers. Figure 1