Toward predictive modeling of catheter-based pulmonary valve replacement into native right ventricular outflow tracts.

BACKGROUND: Pulmonary insufficiency is a consequence of transannular patch repair in Tetralogy of Fallot (ToF) leading to late morbidity and mortality. Transcatheter native outflow tract pulmonary valve replacement has become a reality. However, predicting a secure, atraumatic implantation of a catheter-based device remains a significant challenge due to the complex and dynamic nature of the right ventricular outflow tract (RVOT). We sought to quantify the differences in compression and volume for actual implants, and those predicted by pre-implant modeling. METHODS: We used custom software to interactively place virtual transcatheter pulmonary valves (TPVs) into RVOT models created from pre-implant and post Harmony valve implant CT scans of 5 ovine surgical models of TOF to quantify and visualize device volume and compression. RESULTS: Virtual device placement visually mimicked actual device placement and allowed for quantification of device volume and radius. On average, simulated proximal and distal device volumes and compression did not vary statistically throughout the cardiac cycle (P = 0.11) but assessment was limited by small sample size. In comparison to actual implants, there was no significant pairwise difference in the proximal third of the device (P > 0.80), but the simulated distal device volume was significantly underestimated relative to actual device implant volume (P = 0.06). CONCLUSIONS: This study demonstrates that pre-implant modeling which assumes a rigid vessel wall may not accurately predict the degree of distal RVOT expansion following actual device placement. We suggest the potential for virtual modeling of TPVR to be a useful adjunct to procedural planning, but further development is needed.

Diabetes Risk Assessment in Latinas: Effectiveness of a Brief Diabetes Risk Questionnaire for Detecting Prediabetes in a Community-Based Sample.

OBJECTIVE: Numerous validated questionnaires use self-reported data to quantify individuals' risk of having diabetes or developing it in the future. Evaluations of these tools have primarily used nationally representative data, limiting their application in clinical and community settings. This analysis tested the effectiveness of the American Diabetes Association (ADA) risk questionnaire for identifying prediabetes in a community-based sample of Latinas. METHODS: Data were collected using the ADA risk questionnaire and assessing A1C. Among 204 participants without diabetes, we examined the association between individual characteristics and glycemic status. We then calculated the performance characteristics (sensitivity, specificity, positive predictive value [PPV], and negative predictive value [NPV]) of the ADA risk questionnaire for detecting prediabetes, using A1C results as the gold standard to define the outcome. RESULTS: All participants were women of self-reported Hispanic/Latino ethnicity. Their mean ADA risk score was 5.6 ± 1.6. Latinas who had prediabetes were older, with significantly higher rates of hypertension and a higher ADA risk score than those without prediabetes. At a risk score ≥5-the threshold for high risk set by the ADA-the questionnaire had the following test performance characteristics: sensitivity 77.8%, specificity 41.7%, PPV 76.2%, and NPV 43.9%. CONCLUSION: The ADA risk questionnaire demonstrates reasonable performance for identifying prediabetes in a community-based sample of Latinas. Our data may guide other groups' use of this tool in the same target population. Future research should examine the effectiveness of this questionnaire for recruiting diverse populations into diabetes prevention programs. In addition, unique diabetes risk assessment tools for specific target populations are needed and may outperform questionnaires developed using nationally representative data.

Comparison of 3D Echocardiogram-Derived 3D Printed Valve Models to Molded Models for Simulated Repair of Pediatric Atrioventricular Valves.

Mastering the technical skills required to perform pediatric cardiac valve surgery is challenging in part due to limited opportunity for practice. Transformation of 3D echocardiographic (echo) images of congenitally abnormal heart valves to realistic physical models could allow patient-specific simulation of surgical valve repair. We compared materials, processes, and costs for 3D printing and molding of patient-specific models for visualization and surgical simulation of congenitally abnormal heart valves. Pediatric atrioventricular valves (mitral, tricuspid, and common atrioventricular valve) were modeled from transthoracic 3D echo images using semi-automated methods implemented as custom modules in 3D Slicer. Valve models were then both 3D printed in soft materials and molded in silicone using 3D printed "negative" molds. Using pre-defined assessment criteria, valve models were evaluated by congenital cardiac surgeons to determine suitability for simulation. Surgeon assessment indicated that the molded valves had superior material properties for the purposes of simulation compared to directly printed valves (p < 0.01). Patient-specific, 3D echo-derived molded valves are a step toward realistic simulation of complex valve repairs but require more time and labor to create than directly printed models. Patient-specific simulation of valve repair in children using such models may be useful for surgical training and simulation of complex congenital cases.

Dynamic Three-Dimensional Geometry of the Tricuspid Valve Annulus in Hypoplastic Left Heart Syndrome with a Fontan Circulation.

BACKGROUND: Tricuspid regurgitation (TR) is a significant contributor to morbidity and mortality in patients with hypoplastic left heart syndrome. The goal of this study was to characterize the dynamic annular motion of the tricuspid valve in patients with HLHS with a Fontan circulation and assess the relation to tricuspid valve function. METHODS: Tricuspid annuli of 48 patients with HLHS with a Fontan circulation were modeled at end-diastole, mid-systole, end-systole, and mid-diastole using transthoracic three-dimensional echocardiography and custom code in 3D Slicer. The angle of the anterior papillary muscle (APM) relative to the annular plane in each systolic phase was also measured. RESULTS: Imaging was performed 5.0 years (interquartile range, 2-11 years) after Fontan operation. The tricuspid annulus varies in shape significantly throughout the cardiac cycle, changing in sphericity (P < .001) but not in annular height or bending angle. In univariate modeling, patients with significant TR had larger changes in septolateral diameter, lateral quadrant area, and posterior quadrant area (P < .05 for all) as well as lower (more laterally directed) APM angles (P < .001) than patients with mild or less TR. In multivariate modeling, a 1 mm/(body surface area)0.5 increase in the maximum change in septolateral diameter was associated with a 1.7-fold increase in having moderate or greater TR, while a 10° decrease in APM angle at mid-systole was associated with an almost 2.5-fold increase in moderate or greater TR (P ≤ .01 for all). CONCLUSIONS: The tricuspid annulus in patients with HLHS with a Fontan circulation changes in shape significantly throughout the cardiac cycle but remains relatively planar. Increased change in septolateral diameter and decreased APM angle are strongly associated with the presence of TR. These findings may inform annuloplasty methods and subvalvular interventions in these complex patients.

PREVENT-DM Comparative Effectiveness Trial of Lifestyle Intervention and Metformin.

INTRODUCTION: Although the Diabetes Prevention Program and other clinical trials demonstrated the efficacy of intensive lifestyle interventions (ILI) and metformin to prevent type 2 diabetes, no studies have tested their comparative effects in pragmatic settings. This study was designed to compare the real-world effectiveness of ILI, metformin, and standard care among Hispanic women (Latinas) with prediabetes. STUDY DESIGN: RCT. SETTING/PARTICIPANTS: Ninety-two Latinas, who had a mean hemoglobin A1c of 5.9%, BMI of 33.3 kg/m2, and waist circumference of 97.4 cm (38.3 inches), were recruited from an urban community and randomly assigned to ILI, metformin, or standard care using 1:1:1 allocation. Data were collected from 2013-2015 and analyzed in 2016. INTERVENTION: The 12-month ILI was adapted from the Diabetes Prevention Program's ILI and delivered by community health workers (promotoras) over 24 sessions. Metformin participants received 850 mg twice daily. Those randomized to standard care continued their regular medical care. MAIN OUTCOME MEASURES: Weight and secondary outcomes (waist circumference, blood pressure, hemoglobin A1c, fasting plasma glucose, insulin, and lipids) were assessed at baseline and 12 months. RESULTS: ILI participants demonstrated significantly greater mean weight loss (-4.0 kg, 5.0%) than metformin (-0.9 kg, 1.1%) and standard care participants (+0.8 kg, 0.9%) (p<0.001). The difference in weight loss between metformin and standard care was not significant. The ILI group experienced a greater reduction in waist circumference than standard care (p=0.001), and a marginal improvement in hemoglobin A1c compared with metformin and standard care (p=0.063). CONCLUSIONS: In the first comparative effectiveness trial of diabetes prevention treatments, a 12-month ILI produced significantly greater weight loss than metformin and standard care among Latinas with prediabetes. These data suggest that ILI delivered by promotoras is an effective strategy for preventing diabetes in this high-risk group, which may be superior to metformin. Future pragmatic trials involving larger samples should examine differences in diabetes incidence associated with these treatments.

Image Segmentation and Modeling of the Pediatric Tricuspid Valve in Hypoplastic Left Heart Syndrome.

Hypoplastic left heart syndrome (HLHS) is a single-ventricle congenital heart disease that is fatal if left unpalliated. In HLHS patients, the tricuspid valve is the only functioning atrioventricular valve, and its competence is therefore critical. This work demonstrates the first automated strategy for segmentation, modeling, and morphometry of the tricuspid valve in transthoracic 3D echocardiographic (3DE) images of pediatric patients with HLHS. After initial landmark placement, the automated segmentation step uses multi-atlas label fusion and the modeling approach uses deformable modeling with medial axis representation to produce patient-specific models of the tricuspid valve that can be comprehensively and quantitatively assessed. In a group of 16 pediatric patients, valve segmentation and modeling attains an accuracy (mean boundary displacement) of 0.8 ± 0.2 mm relative to manual tracing and shows consistency in annular and leaflet measurements. In the future, such image-based tools have the potential to improve understanding and evaluation of tricuspid valve morphology in HLHS and guide strategies for patient care.