Using 4D Cardiovascular Magnetic Resonance Imaging to Validate Computational Fluid Dynamics: A Case Study.

Computational fluid dynamics (CFD) can have a complementary predictive role alongside the exquisite visualization capabilities of 4D cardiovascular magnetic resonance (CMR) imaging. In order to exploit these capabilities (e.g.

Patient-specific computational models to support interventional procedures: a case study of complex aortic re-coarctation.

Aims: We report the application of patient-specific computational models to plan the treatment of complex aortic re-coarctation (rCoA) with a proximal aberrant right subclavian artery in a patient who had previously undergone bare metal stenting.

Methods And Results: Clinically acquired images were used to set up patient-specific computational models for finite element (FE) and fluid dynamics (CFD) analyses. The 3D geometry was reconstructed from computed tomography and echocardiography images.

Measurement of in vitro and in vivo stent geometry and deformation by means of 3D imaging and stereo-photogrammetry.

Purpose: To quantify variability of in vitro and in vivo measurement of 3D device geometry using 3D and biplanar imaging.

Methods: Comparison of stent reconstruction is reported for in vitro coronary stent deployment (using micro-CT and optical stereo-photogrammetry) and in vivo pulmonary valve stent deformation (using 4DCT and biplanar fluoroscopy). Coronary stent strut length and inter-strut angle were compared in the fully deployed configuration.

Geometrical and stress analysis of factors associated with stent fracture after melody percutaneous pulmonary valve implantation.

Background: Patients treated with the Melody device (Medtronic) for percutaneous pulmonary valve implantation experience stent fractures in ≈25% of the cases. The aim of this study is to identify the risk factors associated with fracture using 3-dimensional (3D) analyses.

Methods And Results: In situ 3D shape of the Melody stent was reconstructed from 42 patients using procedural biplane fluoroscopy images, after balloon inflation, at systole and diastole.

Uncertainty assessment of imaging techniques for the 3D reconstruction of stent geometry.

This paper presents a quantitative assessment of uncertainty for the 3D reconstruction of stents. This study investigates a CP stent (Numed, USA) used in congenital heart disease applications with a focus on the variance in measurements of stent geometry. The stent was mounted on a model of patient implantation site geometry, reconstructed from magnetic resonance images, and imaged using micro-computed tomography (CT), conventional CT, biplane fluoroscopy and optical stereo-photogrammetry.

Effects of pulmonary artery banding and retrograde aortic arch obstruction on the hybrid palliation of hypoplastic left heart syndrome.

Objectives: The hybrid approach achieves stage 1 palliation of hypoplastic left heart syndrome with flow and physiologic characteristics that are different from those of the surgical Norwood circulations. In addition to having branch pulmonary arterial banding regulating the balance between pulmonary and systemic blood flows, coronary and cerebral perfusion are dependent on retrograde flow through the native aortic arch when aortic atresia is present. Accordingly, we used computational modeling to assess the effects of pulmonary artery banding diameter and retrograde aortic arch hypoplasia or obstruction on the hybrid stage 1 circulation, including the influence on systemic and cerebral oxygen deliveries.

Finite element strategies to satisfy clinical and engineering requirements in the field of percutaneous valves.

Finite element (FE) modelling can be a very resourceful tool in the field of cardiovascular devices. To ensure result reliability, FE models must be validated experimentally against physical data. Their clinical application (e.

Boundary conditions of patient-specific fluid dynamics modelling of cavopulmonary connections: possible adaptation of pulmonary resistances results in a critical issue for a virtual surgical planning.

Cavopulmonary connections are surgical procedures used to treat a variety of complex congenital cardiac defects. Virtual pre-operative planning based on in silico patient-specific modelling might become a powerful tool in the surgical decision-making process. For this purpose, three-dimensional models can be easily developed from medical imaging data to investigate individual haemodynamics.

Virtual and real bench testing of a new percutaneous valve device: a case study.

Aims: To validate patient-specific computational testing of a second-generation device for percutaneous pulmonary valve implantation (PPVI), against realistic in vitro data.

Methods And Results: Tests were initially carried out in a simple loading mode, performing a compliance test on a rapid prototyped cylinder. This model was reproduced computationally and validated against the experimental data.

Use of mathematical modeling to compare and predict hemodynamic effects between hybrid and surgical Norwood palliations for hypoplastic left heart syndrome.

Background: Combining bilateral pulmonary artery banding with arterial duct stenting, the hybrid approach achieves stage 1 palliation for hypoplastic left heart syndrome with different flow characteristics than those after the surgical Norwood procedures. Accordingly, we used computational modeling to assess some of these differences, including influence on systemic and cerebral oxygen deliveries.

Methods And Results: A 3-dimensional computational model of hybrid palliation was developed by the finite volume method, along with models of the Norwood operation with a modified Blalock-Tausig or right ventricle-to-pulmonary artery shunt.

Multiscale models of the hybrid palliation for hypoplastic left heart syndrome.

A less-invasive procedure that combines interventional stent placement in the ductus arteriosus and surgical banding of the branch pulmonary arteries has been recently introduced in the treatment of the hypoplastic left heart syndrome (HLHS). The hemodynamic behaviour of this hybrid approach has not been examined before in a mathematical model. In this study, a mathematical model of the hybrid procedure for HLHS is described, applying a multiscale approach that couples 3D models of the area of the surgical operation and lumped parameter models of the remaining circulation.