Left ventricular trabeculations decrease the wall shear stress and increase the intra-ventricular pressure drop in CFD simulations

Federica Sacco, Bruno Paun, Oriol Lehmkuhl, Tinen L. Iles, Paul A. Iaizzo, Guillaume Houzeaux, Mariano Vázquez, Constantine Butakoff, Jazmin Aguado-Sierra

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The aim of the present study is to characterize the hemodynamics of left ventricular (LV) geometries to examine the impact of trabeculae and papillary muscles (PMs) on blood flow using high performance computing (HPC). Five pairs of detailed and smoothed LV endocardium models were reconstructed from high-resolution magnetic resonance images (MRI) of ex-vivo human hearts. The detailed model of one LV pair is characterized only by the PMs and few big trabeculae, to represent state of art level of endocardial detail. The other four detailed models obtained include instead endocardial structures measuring ≥ 1 mm2 in cross-sectional area. The geometrical characterizations were done using computational fluid dynamics (CFD) simulations with rigid walls and both constant and transient flow inputs on the detailed and smoothed models for comparison. These simulations do not represent a clinical or physiological scenario, but a characterization of the interaction of endocardial structures with blood flow. Steady flow simulations were employed to quantify the pressure drop between the inlet and the outlet of the LVs and the wall shear stress (WSS). Coherent structures were analyzed using the Q-criterion for both constant and transient flow inputs. Our results show that trabeculae and PMs increase the intra-ventricular pressure drop, reduce the WSS and disrupt the dominant single vortex, usually present in the smoothed-endocardium models, generating secondary small vortices. Given that obtaining high resolution anatomical detail is challenging in-vivo, we propose that the effect of trabeculations can be incorporated into smoothed ventricular geometries by adding a porous layer along the LV endocardial wall. Results show that a porous layer of a thickness of 1.2 · 10-2 m with a porosity of 20 kg/m2 on the smoothed-endocardium ventricle models approximates the pressure drops, vorticities and WSS observed in the detailed models.

Original languageEnglish (US)
Article number458
JournalFrontiers in Physiology
Volume9
DOIs
StatePublished - Apr 30 2018

Keywords

  • Left ventricular hemodynamics
  • Left ventricular modeling
  • Papillary muscles
  • Porosity
  • Trabeculae

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