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The torsional behaviour of the heart (i.e. the mutual rotation of the cardiac base and apex) was proved to be sensitive to alterations of some cardiovascular parameters, i.e. preload, afterload and contractility. Moreover, pathologies which affect the fibers architecture and cardiac geometry were proved to alter the cardiac torsion pattern. For these reasons, cardiac torsion represents a sensitive index of ventricular performance. The aim of this work is to provide further insight into physiological and pathological alterations of the cardiac torsion by means of computational analyses, combining a structural model of the two ventricles with simple lumped parameter models of both the systemic and the pulmonary circulations. Starting from diagnostic images, a 3D anatomy based geometry of the two ventricles was reconstructed. The myocytes orientation in the ventricles was assigned according to literature data and the myocardium was modelled as an anisotropic hyperelastic material. Both the active and the passive phases of the cardiac cycle were modelled, and different clinical conditions were simulated. The results in terms of alterations of the cardiac torsion in the presence of pathologies are in agreement with experimental literature data. The use of a computational approach allowed the investigation of the stresses and strains in the ventricular wall as well as of the global hemodynamic parameters in the presence of the considered pathologies. Furthermore, the model outcomes highlight how for specific pathological conditions, an altered torsional pattern of the ventricles can be present, encouraging the use of the ventricular torsion in the clinical practice., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Aims: This study sought to investigate the possible influence of different bifurcation stenting techniques on stent deformation, physical stress, and drug elution using a virtual tool that includes structural, fluid dynamics and drug-eluting numerical models., Methods and Results: A virtual bench test based on explicit dynamics modelling was used to simulate procedures on bifurcated coronary vessels performed according to three different stenting techniques: provisional side branch stenting, culotte, and Tryton-based culotte. Geometrical configurations obtained after virtual stenting simulations were used to perform fluid dynamics and drug elution analyses. The results showed that substantially different patterns of mechanical deformation, shear stress and theoretical drug elution were obtained using the different techniques. Compared with conventional culotte, the dedicated Tryton seems to facilitate the intervention in terms of improved access to the main branch and to lower its biomechanical influence on the coronary bifurcation in terms of mechanical and haemodynamic parameters. However, since the Tryton stent is a bare metal stent, the drug elution obtained is lower., Conclusions: Numerical models might successfully complement the information on stenting procedures obtained with traditional approaches such as in vitro bench testing or clinical trials. Devices dedicated to bifurcations may facilitate procedure completion and may result in specific patterns of mechanical stress, regional blood flow and drug elution.