The clinical stakes are considerable. The aorta is the body’s largest blood vessel, the highway that carries oxygen-rich blood from the heart to every organ and limb. When this vessel is pinched or narrowed as it exits the heart, a hallmark of coarctation of the aorta, blood flow to the lower body is restricted and the fetal heart must pump harder to push blood through the constriction. The condition accounts for an estimated 6% to 8% of all cardiac birth defects, making it one of the more frequently encountered diagnoses a fetal cardiologist must consider. Yet despite its prevalence, coarctation remains one of the most challenging defects to identify prenatally.

The reason for that difficulty lies in the limitations of current screening tools. Standard prenatal testing relies primarily on anatomic information, essentially static pictures of the heart’s structure, rather than on dynamic blood-flow data, to assess fetal heart health. Standard ultrasound and even specialized echocardiograms, noninvasive tests that use sound waves to create images and generate data about a fetus, often fail to detect anatomical and blood flow abnormalities in a developing heart. Worse, ultrasound-based tests sometimes produce false positives, suggesting that an abnormality is present when no such defect actually exists. “Standard prenatal testing and even specialized imaging often fail to detect anatomical problems in the fetal aorta,” Wei says. “By integrating detailed blood flow parameters, we will give doctors a more precise tool to use when diagnosing congenital heart defects.”

The consequences of a missed diagnosis can follow a child for a lifetime. If coarctation of the aorta is not diagnosed early and repaired with surgery, infants can suffer long-term health problems such as high blood pressure, or in severe cases, die. Early detection changes the entire trajectory of care. When clinicians and families know before birth that a defect is present, they can plan for delivery at a center equipped for immediate intervention, schedule surgical repair, and monitor the newborn closely from the first hours of life. “Surgeons can repair many heart problems in babies, but the first, and most important, step is detecting problems,” Wei said. “The earlier we can identify a condition, the more time clinicians and families have to plan for the baby’s care.”

Wei’s answer to this diagnostic gap is a digital twin: a viewable digital replica of an individual patient’s cardiovascular system that can be interrogated on a computer the way a clinician might examine a patient at the bedside. The model will integrate multidimensional, patient-specific data to support clinical decision-making, including assessment of whether a fetal heart defect is present. Rather than relying on a single snapshot of anatomy, the digital twin will simulate how blood actually behaves inside a particular fetus’s aorta, capturing the hemodynamic signatures that a narrowing leaves on pressure, velocity, and wall stress even when the structural change is too subtle for imaging to resolve.

The raw material for this model comes from an unusually rich data source. Wei’s team will draw on fetal heart data collected at more than 15 cardiology programs across North America that are part of the Fetal Heart Society. The database includes information gathered during two-dimensional and three-dimensional ultrasound tests performed on hundreds of racially and ethnically diverse pregnant women, including some whose babies were confirmed after birth to have heart defects. That breadth matters both scientifically and clinically: a model trained on diverse populations is more likely to perform reliably across the full spectrum of patients a prenatal clinic will see, and the inclusion of confirmed postnatal diagnoses gives the researchers ground truth against which their predictions can be checked.

Wei and his team have already used information in the database to create a model representing blood flow in healthy fetal hearts, establishing a baseline of normal hemodynamics. Going forward, the new model will focus on a set of physically meaningful measurements that reflect how the cardiovascular system responds to obstruction. These include the forces exerted on the walls of fetal blood vessels, the pressure and flow characteristics through a narrowed fetal artery, and the resistance that arises when freshly pumped blood collides with blood already moving through the vessel. Each of these parameters encodes information about the geometry and elasticity of the aorta in ways that a static image cannot, which is precisely why the researchers believe flow-based metrics will outperform anatomy-only assessment.

Building a model is only half the challenge; proving that it is trustworthy is the other half. To validate their computational predictions, the researchers will conduct laboratory experiments using 3D-printed silicone models of fetal aortas, paired with fluid and pumping mechanisms that recreate the mechanical conditions of the fetal circulation. These physical phantoms allow the team to compare what the digital twin predicts against what actually happens in a controlled, measurable system with known geometry. Finally, data from the Geisinger healthcare system’s database will be used to evaluate blood flow metrics for better diagnosis of aorta narrowing in the future, closing the loop between computation, experiment, and real clinical outcomes.

The project is a deliberately interdisciplinary effort. Wei is working with Professor Zhongqiang Zhang and Associate Professor Fangfang Wang, both of WPI’s Department of Mathematical Sciences, whose expertise in computational mathematics underpins the numerical machinery of the digital twin, and with Dr. Shuping Ge, a pediatric cardiologist and researcher with the Geisinger healthcare system in Pennsylvania, who brings the clinical perspective needed to ensure the model answers questions doctors actually face. The work also builds on Wei’s broader research program in computational and experimental models of blood flow mechanics. His fetus-related research has been supported by the American Heart Association’s Second Century Faculty Independence Award and a National Institute of Biomedical Imaging and Bioengineering Trailblazer Award, honors recognizing the innovation and potential clinical impact of his work, and he has previously collaborated on pediatric medical devices and 3D-printed blood vessels for heart bypass surgery.

For Wei, the ultimate measure of success is not a publication or a patent but a change in how early and how confidently fetal heart defects are caught. He says that development of a validated digital twin model for coarctation of the fetal aorta will lay a solid foundation for future human studies that could lead to more accurate screening tools and better health outcomes for children with the birth defect. “The goal of my lab is to improve the detection and treatment of cardiovascular disease and, ultimately, to help ensure that patients receive the right care at the right time,” Wei said. If the project succeeds, the faint hemodynamic whispers of a narrowed aorta, invisible to today’s ultrasound screens, may become impossible for medicine to miss.

Subject of Research: Development of a blood flow-based digital twin model for prenatal detection of fetal aortic coarctation

Article Title: Worcester Polytechnic Institute researcher is seeking clues to problems in tiny hearts

Article References: Worcester Polytechnic Institute researcher is seeking clues to problems in tiny hearts. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: fetal heart defects, coarctation of the aorta, digital twin, blood flow modeling, prenatal diagnosis, echocardiography, computational fluid dynamics, 3D printing, National Institutes of Health, Worcester Polytechnic Institute, congenital heart disease, biomedical engineering

Coarctation of the aorta, often abbreviated CoA, affects roughly one in several thousand live births and can remain clinically silent until hypertension or heart failure emerges in adulthood. Even after the narrowing is relieved by surgery or stenting, many patients continue to develop hypertension, diastolic dysfunction, and premature cardiovascular disease. Previous work by the same group and others has hinted that eliminating the trans-coarctation pressure gradient does not always normalize left ventricular function or aortic shear stress, suggesting that something beyond the pressure drop itself shapes long-term outcomes. The new study homes in on one candidate: post-stenotic energy dissipation, the irreversible loss of useful mechanical energy that occurs when high-velocity, disturbed flow exiting the narrowing collides with the complex three-dimensional anatomy of the descending aorta.

To dissect this phenomenon, the team analyzed a cohort of twenty patients with coarctation of the aorta. From computed tomography and magnetic resonance imaging, they extracted detailed anatomical features of the aorta, including the centerline topology—the curved path tracing the vessel’s midline—and the variation in cross-sectional area along the descending aorta. These geometric descriptors capture how sharply the aorta bends, how abruptly its caliber changes, and how the vessel’s axis deviates between the coarctation site and the segments immediately downstream. Rather than treating the aorta as a simple tube, the approach quantifies the actual anatomical landscape through which the jet of blood must travel after it exits the stenosis.

On top of the imaging analysis, the researchers built patient-specific multiscale computational simulations that couple three-dimensional aortic hemodynamics with models of cardiac function and systemic circulation. This framework allows the virtual blood flow to respond both to the local anatomy of each patient’s aorta and to the global behavior of the heart and arterial system. Using these simulations, the team quantified energy dissipation per unit volume in the descending aorta—a measure of how much of the blood’s mechanical energy is converted into heat and turbulence rather than forward motion. The multiscale design matters because energy loss in the aorta cannot be interpreted in isolation; it depends on the pressure and flow waveforms delivered by the left ventricle and on the resistance and compliance of the entire circulation.

The central finding is strikingly geometric. Energy dissipation per unit volume in the descending aorta correlates with the combined effect of two quantities: the kinetic energy available in the flow at the coarctation site, and the centerline tangent angle difference between the coarctation and the downstream descending aorta. In plain terms, it is not enough to know how fast the blood is moving as it leaves the narrowing; one must also know how much the vessel’s axis changes direction just downstream. A jet that exits the stenosis into a sharply angled or tortuous segment cannot follow the vessel wall smoothly, and the resulting flow separation, secondary motions, and turbulence dissipate far more energy than the same jet entering a well-aligned segment.

This angle-based insight reframes a familiar clinical observation. Post-stenotic dilatation—the widening of the aorta just beyond a narrowing—has long been recognized on imaging, and computational studies have linked it to the disturbed hemodynamics downstream of stenoses. The new results suggest that the same anatomical misalignment that promotes dilatation also acts as an energy sink, converting the kinetic energy generated by the ventricle into wasted, irreversible losses. Two patients with identical pressure gradients could therefore carry very different energetic burdens depending on the shape of their descending aortas, a distinction that the standard diagnostic metric is blind to.

Crucially, the study connects these downstream losses to the heart itself. The geometric and energetic parameters—the kinetic energy at the coarctation and the centerline angle difference—were found to significantly influence the left ventricular workload expended to compensate for post-stenotic energy loss. In other words, when the aorta’s geometry squanders the energy the heart delivers, the ventricle must do additional work to maintain adequate perfusion of the body. Over years, this chronic energetic penalty plausibly contributes to the left ventricular hypertrophy, diastolic dysfunction, and exercise intolerance documented in adults with repaired coarctation, outcomes that prior clinical studies have linked to abnormal arterial load indices even when resting blood pressure appears controlled.

The implications for clinical practice are substantial. Current guidelines from the American Heart Association and the European Society of Cardiology rely heavily on pressure gradients, imaging-derived indices of narrowing severity, and ventricular function to guide decisions about intervention. The new findings argue for incorporating anatomical and energetic metrics—centerline curvature, angle change, cross-sectional area variation, and computed energy dissipation—alongside pressure gradients when assessing disease severity and cardiac burden. Because the required inputs come from CT and MRI images that patients already undergo, the geometric analysis could in principle be folded into existing imaging workflows, and the computational framework builds on the group’s broader program of non-invasive, patient-specific diagnostic tools for valvular and vascular disease.

The work also resonates with a growing body of literature on cardiovascular energetics. Four-dimensional flow magnetic resonance imaging has been used to measure turbulent kinetic energy in aortic stenosis and coarctation, and studies of hypertrophic cardiomyopathy have shown that individualized computational modeling can reveal energetic inefficiencies invisible to conventional metrics. By identifying a simple, image-derived geometric predictor of energy loss, the McMaster team offers a bridge between high-fidelity simulation and practical clinical assessment. The method’s reliance on centerline morphology—something extractable from standard angiographic and tomographic data—makes it more translatable than approaches requiring specialized flow-sensitive sequences.

Limitations and next steps remain. The cohort comprised twenty patients, and the study, supported by NSERC Discovery and Alliance grants and computational resources from the Digital Research Alliance of Canada, will need validation in larger and more diverse populations, including patients before and after intervention. Longitudinal studies will be required to test whether geometrically driven energy dissipation predicts ventricular remodeling, hypertension, or clinical events over time. Still, the message is clear and potentially practice-changing: in coarctation of the aorta, the pressure drop across the narrowing is only the opening chapter of the story. The shape of the vessel that receives the jet—the bends, the angles, the tapering of the descending aorta—determines how much of the heart’s energy survives the journey, and how hard the ventricle must work to make up the difference. Reading the aorta’s centerline, the study suggests, may be as important as measuring its pressures.

Subject of Research: Geometric determinants of post-stenotic flow energy loss and left ventricular workload in coarctation of the aorta

Article Title: Geometric Determinants of Post-stenotic Energetics in Coarctation of Aorta: Linking Centerline Morphology to Downstream Energy Loss

Article References: Daeian, M., Karbassi, A., Ganame, J., Smith, S., & Keshavarz-Motamed, Z. (2026). Geometric Determinants of Post-stenotic Energetics in Coarctation of Aorta: Linking Centerline Morphology to Downstream Energy Loss. Annals of Biomedical Engineering. https://doi.org/10.1007/s10439-026-04351-y

Image Credits: AI Generated

DOI: 10.1007/s10439-026-04351-y

Keywords: aortic coarctation, hemodynamics, energy dissipation, centerline morphology, left ventricular workload, computational fluid dynamics, descending aorta, pressure gradient, patient-specific modeling, cardiac function, viscous dissipation, medical imaging