Distensibility of Deformable Aortic Replicas Assessed by an Integrated In-Vitro and In-Silico Approach.

The correct estimation of the distensibility of deformable aorta replicas is a challenging issue, in particular when its local characterization is necessary. We propose a combined in-vitro and in-silico approach to face this problem. First, we tested an aortic silicone arch in a pulse-duplicator analyzing its dynamics under physiological working conditions.

Beating heart implantation of transventricular artificial cordae: How can access site selection and leaflet insertion improve mitral regurgitation correction?

NeoChord-DS1000-System (NC) and The Harpoon-Mitral-Repair-System (H-MRS) are two trans-apical chordal implantation devices developed for the treatment of degenerative mitral valve (MV) regurgitation (DMR) either if as Fibroelastic-Deficiency (FED), Forma-Frusta (FF), or Barlow (B) presentation. The aim of this study is to evaluate some of the advantages and disadvantages of these two different devices by performing numerical simulation analyses focused on different transventricular access sites in all subsets of DMR presentations. By applying a novel approach for the development of patient-specific MV domains we worked out a set of numerical simulations of the artificial chordae implantation.

Ventricular outflow tract obstruction: An in-silico model to relate the obstruction to hemodynamic quantities in cardiac paediatric patients.

Background: Right (R) or left (L) ventricular outflow tract (VOT) obstruction can be either a dynamic phenomenon or a congenital anatomic lesion, which requires a prompt and optimal timing of treatment to avoid a pathological ventricular remodelling.

Objective: To develop a simple and reliable numerical tool able to relate the R/L obstruction size with the pressure gradient and the cardiac output. To provide indication of the obstruction severity and be of help in the clinical management of patients and designing the surgical treatment for obstruction mitigation.

Ventricular wall stress and wall shear stress homeostasis predicts cardiac remodeling during pregnancy: A modeling study.

Pregnancy is a unique and dynamic process characterized by significant changes in the maternal cardiovascular system that are required to satisfy the increased maternal and fetal metabolic demands. Profound structural and hemodynamic adaptations occur during healthy pregnancy that allows the mother to maintain healthy hemodynamics and provide an adequate uteroplacental blood circulation to ensure physiological fetal development. Investigating these adaptations is crucial for understanding the physiology of pregnancy and may provide important insights for the management of high-risk pregnancies.

Numerical Models Can Assist Choice of an Aortic Phantom for In Vitro Testing.

(1) Background: The realization of appropriate aortic replicas for in vitro experiments requires a suitable choice of both the material and geometry. The matching between the grade of details of the geometry and the mechanical response of the materials is an open issue that deserves attention. (2) Methods: To explore this issue, we performed a series of Fluid-Structure Interaction simulations, which compared the dynamics of three aortic models.

Understanding and recognition of the right ventricular function and dysfunction via a numerical study.

The role played by the right ventricular (RV) dysfunction has long been underestimated in clinical practice. Recent findings are progressively confirming that when the RV efficiency deteriorates both the right and the left circulation is (significantly) affected, but studies dedicated to a detailed description of RV hemodynamic role still lack. In response to such a gap in knowledge, this work proposes a numerical model that for the first time evaluates the effect of isolated RV dysfunction on the whole circulation.

A female-specific cardiovascular lumped-parameter model.

Historically, cardiovascular computational models have been developed considering the case of a 70 Kg male patient. However, hemodynamic quantities differ widely due to sex, age, and weight. In this study, we developed a female-specific model of the blood circulation of a young (18-40 y.

The neochord mitral valve repair procedure: Numerical simulation of different neochords tensioning protocols.

Transapical off-pump mitral valve repair with neochord implantation is an established technique for minimally-invasive intervention on mitral valve prolapse/flail. The procedure involves the positioning of artificial chords, whose length/tension is adjusted intraoperatively, adopting different methods based on the experience of the surgeon. This unsystematic approach occasionally leads to complications such as leaflet rupture and excessive/insufficient load on the neochords.

Form follows function: estimation of CSF flow in the third ventricle-aqueduct-fourth ventricle complex modeled as a diffuser/nozzle pump.

Objective: In the last 20 years, researchers have debated cerebrospinal fluid (CSF) dynamics theories, commonly based on the classic bulk flow perspective. New hypotheses do not consider a possible hydraulic impact of the ventricular morphology. The present study investigates, by means of a mathematical model, the eventual role played by the geometric shape of the "third ventricle-aqueduct-fourth ventricle" complex in CSF circulation under the assumption that the complex behaves like a diffuser/nozzle (DN) pump.

In Vitro and Ex Vivo Hemodynamic Testing of an Innovative Occluder for Paravalvular Leak After Transcather Aortic Valve Implantation.

This study aims at achieving a proof-of-concept for a novel device designed to occlude the orifices that may form between transcatheter valves and host tissues after TAVI. The device effect on the performance of a SAPIEN XT with a paravalvular gap was assessed into an in vitro and ex vivo pulse duplicator. The in vitro tests were performed complying with the standard international regulations, measuring the trasvalvular pressure and regurgitant volumes with and without the paravalvular gap, and with the occluder correctly positioned into the gap.

In vitro assessment of pacing as therapy for aortic regurgitation.

Background And Objective: Clinical evaluation of pacing therapy in mitigating the aortic insufficiency after transchateter aortic valve implantation often gives contradictory outcomes. This study presents an in vitro investigation aimed at clarifying the effect of pacing on paravalvular leakage.

Methods: A series of in vitro tests reproducing the heart operating changes clinically obtained by pacing was carried out in a 26 mm Edwards Sapien XT prosthesis with mild paravalvular leakage.

A Red Blood Cell Model to Estimate the Hemolysis Fingerprint of Cardiovascular Devices.

One of the most relevant and open issues within cardiovascular prosthetic hemodynamic performance is a realistic quantification of the damage sustained by red blood cells (RBCs). Specifically, the optimal design of bileaflet mechanical heart valves (BMHVs) requires both low shear stresses along the leaflets and short particle resident times. This study approaches RBC damage estimation by developing a numerical model of RBCs and computing the damage sustained by a set of passive RBCs immersed within in vitro flows.

Integrated strategy for in vitro characterization of a bileaflet mechanical aortic valve.

Background: Haemodynamic performance of heart valve prosthesis can be defined as its ability to fully open and completely close during the cardiac cycle, neither overloading heart work nor damaging blood particles when passing through the valve. In this perspective, global and local flow parameters, valve dynamics and blood damage safety of the prosthesis, as well as their mutual interactions, have all to be accounted for when assessing the device functionality. Even though all these issues have been and continue to be widely investigated, they are not usually studied through an integrated approach yet, i.

In vitro performance investigation of SynCardia™ Freedom® driver via patient simulator mock loop.

Purpose: The gold standard therapy for patients with advanced heart failure is heart transplant. The gap between donors and patients in waiting lists promoted the development of circulatory support devices, such as the total artificial heart (TAH). Focusing on in vitro tests performed with CardioWest™ TAH (CW) driven by the SynCardia Freedom® portable driver (FD) the present study goals are: i) prove the reliability of a hydraulic circuit used as patient simulator to replicate a quasi-physiological scenario for various hydrodynamic conditions, ii) investigate the hydrodynamic performance of the CW FD, iii) help clinicians in possible interpretation of clinical cases outcomes.

Physiological vortices in the sinuses of Valsalva: An in vitro approach for bio-prosthetic valves.

Purpose: The physiological flow dynamics within the Valsalva sinuses, in terms of global and local parameters, are still not fully understood. This study attempts to identify the physiological conditions as closely as possible, and to give an explanation of the different and sometime contradictory results in literature.

Methods: An in vitro approach was implemented for testing porcine bio-prosthetic valves operating within different aortic root configurations.

In vitro hemodynamic testing of Amplatzer plugs for paravalvular leak occlusion after transcatheter aortic valve implantation.

Objective: We aimed to in-vitro test Amplatzer devices (Amplatzer Vascular Plug II and Amplatzer Vascular Plug III, SJM, St. Paul, MN) in closing PVL generated by transcatheter balloon expandable aortic valve prosthesis in order to quantify the effective treatment of PVL.

Background: Transcatheter aortic valve implantation (TAVI) procedures represent the treatment of choice for high risk patients.

Ultrasound phonocardiography for detecting thrombotic formations on bileaflet mechanical heart valves.

Background And Aim Of The Study: The main disadvantage of a mechanical heart valve (MHV) is thrombosis, a serious complication that is associated with high morbidity and mortality. The early detection of thrombotic formations is crucial for a prompt diagnosis and correct therapy before critical symptoms appear in patients. The present study describes the in-vitro assessment of thrombotic deposits by ultrasound phonocardiography on five commercially available bileaflet MHVs.

In-vitro detection of thrombotic formation on bileaflet mechanical heart valves.

Background And Aim Of The Study: As with all mechanical prostheses, bileaflet heart valves are prone to thrombus formation, reduced hemodynamic performance, and the occurrence of embolic events. The early detection of thrombotic formations is crucial for correct diagnosis and adequate therapy. The study aim was to analyze the power spectra of the phonocardiographic signals acquired in vitro for various thrombotic deposits reproduced on a bileaflet mechanical valve, in order to monitor and classify their presence.

Comparative classification of thrombotic formations on bileaflet mechanical heart valves by phonographic analysis.

Haemodynamic performance of bileaflet mechanical heart valves can be severely affected by the formation of thrombotic deposits. Hence, early detection of thrombi is fundamental for a prompt diagnosis and adequate therapy. This article aims at designing a novel diagnostic and prognostic tool able to detect valvular thrombosis at early stages of formation, i.