Cardiovascular Simulation as a Decision Support Tool

The variable presentation of clinical disease in pediatric patients with congenital and acquired heart disease makes standardized care challenging. This is further enforced by the ongoing growth and remodeling of the heart and vasculature in the individual child and the multitude of available treatment options. The clinical challenge is rather to individualize treatment based on all available information. One option toward individualization of treatment is to use all available information as an input for clinical modeling. Simulation is not able to handle all the complexities in these clinical cases but may be useful in helping to handle the load of information and even look for missing information when analyzing the disease state and the effect of different treatment options in detail. We believe that a synthesis between clinical experience, available scientifical evidence from clinical studies, and predictions from simulations will improve decision making in future pediatric cardiology

Computational Fluid Dynamics Support for Fontan Planning in Minutes, Not Hours : The Next Step in Clinical Pre-Interventional Simulations

Computational fluid dynamics (CFD) modeling may aid in planning of invasive interventions in Fontan patients. Clinical application of current CFD techniques is however limited by complexity and long computation times. Therefore, we validated a "lean" CFD method to magnetic resonance imaging (MRI) and an "established" CFD method, ultimately aiming to reduce complexity to enable predictive CFD during ongoing interventions. Fifteen Fontan patients underwent MRI for CFD modeling. The differences between lean and established approach, in hepatic and total flow percentage to the left pulmonary artery (%LPA), power loss and relative wall shear stress area were 1.5 ± 4.0%, -0.17 ± 1.1%, -0.055 ± 0.092 mW and 1.1 ± 1.4%. Compared with MRI, the lean and established method showed a bias in %LPA of -1.9 ± 3.4% and -1.8 ± 3.1%. Computation time was for the lean and established approach 3.0 ± 2.0 min and 7.0 ± 3.4 h, respectively. We conclude that the proposed lean method provides fast and reliable results for future CFD support during interventions

Simulation of aortopulmonary collateral flow in Fontan patients for use in prediction of interventional outcomes

Purpose: Patients with complex congenital heart disease may need to be converted to a Fontan circulation with systemic venous return surgically connected to the pulmonary circulation. These patients frequently form aortopulmonary collaterals (APC), that is arterial inflows to the pulmonary artery vascular tree. The aim of this study was to develop a method to calculate the effect of APC on the pulmonary flow distribution based on magnetic resonance imaging (MRI) measurements and computational fluid dynamics simulations in order to enable prediction of interventional outcomes in Fontan patients.Methods: Patient-specific models of 11 patients were constructed in a 3D-design software based on MRI segmentations. APC flow was quantified as the difference between pulmonary venous flow and pulmonary artery flow, measured by MRI. A method was developed to include the modulating effect of the APC flow by calculating the patient-specific relative pulmonary vascular resistance. Simulations, including interventions with a Y-graft replacement and a stent dilatation, were validated against MRI results.Results: The bias between simulated and MRI-measured fraction of blood to the left lung was 29 53%. Including the effects of the APC flow in the simulation (n = 6) reduced simulation error from 98 70% to 52 63%. Preliminary findings in two patients show that the effect of surgical and catheter interventions could be predicted using the demonstrated methods.Conclusions: The work demonstrates a novel method to include APC flow in predictive simulations of Fontan hemodynamics. APC flow was found to have a significant contribution to the pulmonary flow distribution in Fontan patients

Comparison of 2D and 4D Flow MRI in Neonates Without General Anesthesia

BackgroundNeonates with critical congenital heart disease require early intervention. Four-dimensional (4D) flow may facilitate surgical planning and improve outcome, but accuracy and precision in neonates are unknown.PurposeTo 1) validate two-dimensional (2D) and 4D flow MRI in a phantom and investigate the effect of spatial and temporal resolution; 2) investigate accuracy and precision of 4D flow and internal consistency of 2D and 4D flow in neonates; and 3) compare scan time of 4D flow to multiple 2D flows.Study TypePhantom and prospective patients.PopulationA total of 17 neonates with surgically corrected aortic coarctation (age 18 days [IQR 11–20]) and a three-dimensional printed neonatal aorta phantom.Field Strength/SequenceA 5 T, 2D flow and 4D flow.AssessmentIn the phantom, 2D and 4D flow volumes (ascending and descending aorta, and aortic arch vessels) with different resolutions were compared to high-resolution reference 2D flow. In neonates, 4D flow was compared to 2D flow volumes at each vessel. Internal consistency was computed as the flow volume in the ascending aorta minus the sum of flow volumes in the aortic arch vessels and descending aorta, divided by ascending aortic flow.Statistical testsBland–Altman plots, Pearson correlation coefficient (r), and Student's t-tests.ResultsIn the phantom, 2D flow differed by 0.01 ± 0.02 liter/min with 1.5 mm spatial resolution and −0.01 ± 0.02 liter/min with 0.8 mm resolution; 4D flow differed by −0.05 ± 0.02 liter/min with 2.4 mm spatial and 42 msec temporal resolution, −0.01 ± 0.02 liter/min with 1.5 mm, 42 msec resolution and −0.01 ± 0.02 liter/min with 1.5 mm, 21 msec resolution. In patients, 4D flow and 2D flow differed by −0.06 ± 0.08 liter/min. Internal consistency in patients was −11% ± 17% for 2D flow and 5% ± 13% for 4D flow. Scan time was 17.1 minutes [IQR 15.5–18.5] for 2D flow and 6.2 minutes [IQR 5.3–6.9] for 4D flow, P < 0.0001.Data ConclusionNeonatal 4D flow MRI is time efficient and can be acquired with good internal consistency without contrast agents or general anesthesia, thus potentially expanding 4D flow use to the youngest and smallest patients.Evidence Level1Technical EfficacyStage