CT-Based Analysis of Left Ventricular Hemodynamics Using Statistical Shape Modeling and Computational Fluid Dynamics

Abstract

BackgroundCardiac computed tomography (CCT) based computational fluid dynamics (CFD) allows to assess intracardiac flow features, which are hypothesized as an early predictor for heart diseases and may support treatment decisions. However, the understanding of intracardiac flow is challenging due to high variability in heart shapes and contractility. Using statistical shape modeling (SSM) in combination with CFD facilitates an intracardiac flow analysis. The aim of this study is to prove the usability of a new approach to describe various cohorts.Materials and MethodsCCT data of 125 patients (mean age: 60.6 ± 10.0 years, 16.8% woman) were used to generate SSMs representing aneurysmatic and non-aneurysmatic left ventricles (LVs). Using SSMs, seven group-averaged LV shapes and contraction fields were generated: four representing patients with and without aneurysms and with mild or severe mitral regurgitation (MR), and three distinguishing aneurysmatic patients with true, intermediate aneurysms, and globally hypokinetic LVs. End-diastolic LV volumes of the groups varied between 258 and 347 ml, whereas ejection fractions varied between 21 and 26%. MR degrees varied from 1.0 to 2.5. Prescribed motion CFD was used to simulate intracardiac flow, which was analyzed regarding large-scale flow features, kinetic energy, washout, and pressure gradients.ResultsSSMs of aneurysmatic and non-aneurysmatic LVs were generated. Differences in shapes and contractility were found in the first three shape modes. Ninety percent of the cumulative shape variance is described with approximately 30 modes. A comparison of hemodynamics between all groups found shape-, contractility- and MR-dependent differences. Disturbed blood washout in the apex region was found in the aneurysmatic cases. With increasing MR, the diastolic jet becomes less coherent, whereas energy dissipation increases by decreasing kinetic energy. The poorest blood washout was found for the globally hypokinetic group, whereas the weakest blood washout in the apex region was found for the true aneurysm group.ConclusionThe proposed CCT-based analysis of hemodynamics combining CFD with SSM seems promising to facilitate the analysis of intracardiac flow, thus increasing the value of CCT for diagnostic and treatment decisions. With further enhancement of the computational approach, the methodology has the potential to be embedded in clinical routine workflows and support clinicians.

Predicting one-year left ventricular mass index regression following transcatheter aortic valve replacement in patients with severe aortic stenosis: A new era is coming

“…The most popular application of SSA is classification, in which shape features are leveraged to organize the subjects into two or more groups. For instance, the differences in the first bunch of PCA components have been used to distinguish aneurysmatic and non-aneurysmatic LV shapes ( 21 ). We have also previously studied hemodynamics in patients with ascending aortic aneurysm using SSA routines ( 22 ) and disclosed that shape numbers, in contrast to first-hand geometrical metrics such as maximum aortic diameter, are better predictors for the thoracic ascending aortic dissection risk.…”

Different hemodynamic factors cause the occurrence of superior mesenteric atherosclerotic stenosis and superior mesenteric artery dissection

“…Tetrahedral mesh was divided and the prism layer was created by using ICEM-CFD (Ansys, Canonsburg, PA, USA). Steady-state flow simulations corresponding to the flow conditions at the patient-specific systolic peak were performed using the CFD solver in Fluent (Ansys, Canonsburg, PA, USA) by solving a k-ω SST transition turbulence model ( 13 ). Blood was treated as an in compressible Newtonian fluid with a density of 1,045 kg/m 3 and a dynamic viscosity of 0.00365 Pa·s ( 14 ).…”

Inter‐model and inter‐modality analysis of left ventricular hemodynamics: Comparative study of two CFD approaches based on echocardiography and magnetic resonance imaging

“…Due to the acquisition of the volumetric sequence in an apical view, the apical-distant anatomical structures (LA and AO), were not adequately resolved as a whole. Thus, generic LA and AO shapes as in [17,37] were used. From the parasternal short axis AV sequence, the projected AV orifice area was measured.…”

“…In contrast, the application of numerical methods, like computational fluid dynamics (CFD), on medical images provides the opportunity for high-resolution flow analysis. Additionally, CFD allows computing biomarkers like washout or blood mixing [2,17], and the performance of virtual treatments [20,46,47]. Driven by these potentials, CFD is increasingly used to assess relevant hemodynamic parameters in the LV.…”