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Cardiovascular Engineering and Technology

Vrishank Raghav, Sudeep Sastry, Neelakantan Saikrishnan
Experimental flow field characterization is a critical component of the assessment of the hemolytic and thrombogenic potential of heart valve substitutes, thus it is important to identify best practices for these experimental techniques. This paper presents a brief review of commonly used flow assessment techniques such as Particle image velocimetry (PIV), Laser doppler velocimetry, and Phase contrast magnetic resonance imaging and a comparison of these methodologies. In particular, recommendations for setting up planar PIV experiments such as recommended imaging instrumentation, acquisition and data processing are discussed in the context of heart valve flows...
March 12, 2018: Cardiovascular Engineering and Technology
Sarifuddin, Prashanta Kumar Mandal
Angioplasty with drug-coated balloons (DCBs) using excipients as drug carriers is emerging as a potentially viable strategy demonstrating clinical efficacy and proposing additional compliance for the treatment of obstructive vascular diseases. An attempt is made to develop an improved computational model where attention has been paid to the effect of interstitial flow, that is, plasma convection and internalization of bound drug. The present model is capable of capturing the phenomena of the transport of free drug and its retention, and also the internalization of drug in the process of endocytosis to atherosclerotic vessel of heterogeneous tissue composition comprising of healthy tissue, as well as regions of fibrous cap, fibro-fatty, calcified and necrotic core lesions...
March 5, 2018: Cardiovascular Engineering and Technology
Emily A Turner, Marzieh K Atigh, Megan M Erwin, Uwe Christians, Saami K Yazdani
Drug coated balloons (DCB) are becoming the standard-care treatment for peripheral arterial disease (PAD). DCB use excipients to transfer and retain anti-proliferative drugs, such as paclitaxel. Excipients thus play a vital role in the design and function of DCB, however methods to coat balloons with excipients and anti-proliferative drugs remain unknown. The goal of this study was to thus develop an approach to coat and evaluate DCB for various excipients. An air sprayer method was developed to deposit paclitaxel and various excipients onto non-coated commercially available angioplasty balloons...
March 1, 2018: Cardiovascular Engineering and Technology
Brandon Kovarovic, Henry H Woo, David Fiorella, Baruch B Lieber, Chander Sadasivan
Cerebral angiography involves the antegrade injection of contrast media through a catheter into the vasculature to visualize the region of interest under X-ray imaging. Depending on the injection and blood flow parameters, the bolus of contrast can propagate in the upstream direction and proximal to the catheter tip, at which point contrast is said to have refluxed. In this in vitro study, we investigate the relationship of fundamental hemodynamic variables to this phenomenon. Contrast injections were carried out under steady and pulsatile flow using various vessel diameters, catheter sizes, working fluid flow rates, and injection rates...
March 1, 2018: Cardiovascular Engineering and Technology
Avik Basu, Carla Lacerda, Zhaoming He
The Tricuspid valve (TV) annulus is a transition structure from the leaflets to the myocardium, with 3 different annulus segments corresponding to the TV leaflets, which includes both basal leaflets and bordering myocardium. The objective of this study was to understand TV annulus mechanical properties and correlate it to the biological composition. The uniaxial testing of the annulus segments from ten porcine TVs was performed to measure Young's modulus (E) and extensibility (εT ). Western blotting and histology were executed...
February 26, 2018: Cardiovascular Engineering and Technology
Marcus W Ni, Ray O Prather, Giovanna Rodriguez, Rachel Quinn, Eduardo Divo, Mark Fogel, Alain J Kassab, William M DeCampli
Children born with anatomic or functional "single ventricle" must progress through two or more major operations to sustain life. This management sequence culminates in the total cavopulmonary connection, or "Fontan" operation. A consequence of the "Fontan circulation", however, is elevated central venous pressure and inadequate ventricular preload, which contribute to continued morbidity. We propose a solution to these problems by increasing pulmonary blood flow using an "injection jet" (IJS) in which the source of blood flow and energy is the ventricle itself...
February 20, 2018: Cardiovascular Engineering and Technology
Biao Si, Bin Qiao, Guang Yang, Meng Zhu, Fengyu Zhao, Tongjian Wang, Na Li, Xiaopeng Ji, Guanghong Ding
The effect of additional pulmonary blood flow (APBF) on the hemodynamics of bilateral bidirectional Glenn (BBDG) connection was marginally discussed in previous studies. This study assessed this effect using patient-specific numerical simulation. A 15-year-old female patient who underwent BBDG was enrolled in this study. Patient-specific anatomy, flow waveforms, and pressure tracings were obtained using computed tomography, Doppler ultrasound technology, and catheterization, respectively. Computational fluid dynamic simulations were performed to assess flow field and derived hemodynamic metrics of the BBDG connection with various APBF...
January 22, 2018: Cardiovascular Engineering and Technology
Mikhail Golman, William Padovano, Leonid Shmuylovich, Sándor J Kovács
Conventional echocardiographic diastolic function (DF) assessment approximates transmitral flow velocity contours (Doppler E-waves) as triangles, with peak (Epeak), acceleration time (AT), and deceleration time (DT) as indexes. These metrics have limited value because they are unable to characterize the underlying physiology. The parametrized diastolic filling (PDF) formalism provides a physiologic, kinematic mechanism based characterization of DF by extracting chamber stiffness (k), relaxation (c), and load (x o ) from E-wave contours...
January 16, 2018: Cardiovascular Engineering and Technology
Saleh Hassanzadeh Gharaie, Bobak Mosadegh, Yosry Morsi
This paper describes a computational method to simulate the non-linear structural deformation of a polymeric aortic valve under physiological conditions. Arbitrary Lagrangian-Eulerian method is incorporated in the fluid-structure interaction simulation, and then validated by comparing the predicted kinematics of the valve's leaflets to in vitro measurements on a custom-made polymeric aortic valve. The predicted kinematics of the valve's leaflets was in good agreement with the experimental results with a maximum error of 15% in a single cardiac cycle...
January 10, 2018: Cardiovascular Engineering and Technology
Marziyeh Khodadoust, Davod Mohebbi-Kalhori, Nafiseh Jirofti
In spite of advances have been made during the past decades, the problems associated with small-diameter vascular grafts, including low patency and compliance mismatch and in consequence of that thrombosis, aneurysm and intimal hyperplasia are still challenges. To address these problems, net polyurethane (PU) and poly (ethylene terephthalate) (PET) polymers and hybrid PU/PET were electrospun to create three different types of small-diameter vascular scaffolds due to their unique physicochemical characteristics: PU, PET, and novel hybrid PU/PET scaffolds...
March 2018: Cardiovascular Engineering and Technology
Anna C Bobel, Peter E McHugh
The desire to overcome the limitations of cardiovascular metal stents is driven by the global clinical need to improve patient outcomes. The opportunity for fully polymeric stents made from materials like Poly-L-lactide Acid (PLLA) is significant. Unfortunately, this potential has not been fully realised due to pressing concerns regarding the radial strength and recoil associated with material stiffness and recoverability. In an effort to achieve effective and reliable performance, it is conceivable that a certain degree of shape memory effect (SME) could be beneficial in order to improve on high recoil associated with fully polymeric stents...
December 14, 2017: Cardiovascular Engineering and Technology
Robert E Smith, P Alex Smith, William E Cohn
A minimally invasive ventricular assist device is under development for percutaneous insertion into the left atrium via transseptal access from the right atrium (RA). This study aimed to mathematically describe the vascular anatomy along possible insertion pathways to determine the device's maximum outer dimensions. We developed 2-dimensional mathematical models describing the vascular anatomy to the RA from three access points: subclavian vein (SCV), internal jugular vein (IJV), and femoral vein (FV). All pathways terminated by turning from the superior or inferior vena cava (SVC/IVC) into the RA...
December 2017: Cardiovascular Engineering and Technology
Hamed Rezaie, Ali Ashrafizadeh, Afsaneh Mojra
Circle of Willis (CoW) is one of the most important cerebral arteries in the human body and various attempts have been made to study the hemodynamic of blood flow in this vital part of the brain. In the present study, blood flow in a patient specific CoW is numerically modeled to predict disease-prone regions of the CoW. Medical images and computer aided design software are used to construct a realistic three-dimensional model of the CoW for this particular case. The arteries are considered as elastic conduits and the interactions between arterial walls and the blood flow are taken into account...
December 2017: Cardiovascular Engineering and Technology
Narine Muselimyan, Mohammed Al Jishi, Huda Asfour, Luther Swift, Narine A Sarvazyan
The purpose of this study was to evaluate structural and optical properties of atrial tissue from common animal models and to compare it with human atria. We aimed to do this in a format that will be useful for development of better ablation tools and/or new means for visualizing atrial lesions. Human atrial tissue from clinically relevant age group was compared and contrasted with atrial tissue of large animal models commonly available for research purposes. These included pigs, sheep, dogs and cows. The presented data include area measurements of smooth atrial surface available for ablation and estimates of thickness of collagen and muscle for five different species...
December 2017: Cardiovascular Engineering and Technology
Yen Ngoc Nguyen, Munirah Ismail, Foad Kabinejadian, Chi Wei Ong, Edgar Lik Wui Tay, Hwa Liang Leo
The increased understanding of right heart diseases has led to more aggressive interventions to manage functional tricuspid regurgitation (FTR). In some cases of FTR, prosthetic valve replacement is typically considered when concomitant organic components or significant geometrical distortions are involved in the pathology of the tricuspid valve. However, little is known of the performance of current devices in the right heart circulation. In this study, a novel in vitro mock circulatory system that incorporated a realistic tricuspid valve apparatus in a patient-specific silicon right ventricle (RV) was designed and fabricated...
December 2017: Cardiovascular Engineering and Technology
Mehmet Alkan, Raef Madanieh, Niel N Shah, Muhammad U Dogar, Parin N Shah, Sameera Ishtiaq, Constantine E Kosmas, Timothy J Vittorio
The prevalence of heart failure (HF) is continuously rising in both the industrialized and non-industrialized nations. Despite current therapeutic advances, prognosis of HF patients remains poor. Presently, therapeutic pharmacological and device strategies for HF with reduced ejection fraction (HFrEF) are mostly palliative and do not induce regeneration of lost myocardial tissue. Stem cell therapy has demonstrated promising results in clinical studies by promoting myocardial restoration in HFrEF subjects. Despite decades of investigation, many challenges remain unanswered to the widespread clinical application of stem cell therapy for HFrEF...
December 2017: Cardiovascular Engineering and Technology
Michael J Moulton, Brian D Hong, Timothy W Secomb
The eventual goal of this study is to develop methods for estimating dynamic stresses in the left ventricle (LV) that could be used on-line in clinical settings, based on routinely available measurements. Toward this goal, a low-order theoretical model is presented, in which LV shape is represented using a small number of parameters, allowing rapid computational simulations of LV dynamics. The LV is represented as a thick-walled prolate spheroid containing helical muscle fibers with nonlinear passive and time-dependent active contractile properties...
December 2017: Cardiovascular Engineering and Technology
Andrés Caballero, Wenbin Mao, Liang Liang, John Oshinski, Charles Primiano, Raymond McKay, Susheel Kodali, Wei Sun
This study aims to investigate the capability of smoothed particle hydrodynamics (SPH), a fully Lagrangian mesh-free method, to simulate the bulk blood flow dynamics in two realistic left ventricular (LV) models. Three dimensional geometries and motion of the LV, proximal left atrium and aortic root are extracted from cardiac magnetic resonance imaging and multi-slice computed tomography imaging data. SPH simulation results are analyzed and compared with those obtained using a traditional finite volume-based numerical method, and to in vivo phase contrast magnetic resonance imaging and echocardiography data, in terms of the large-scale blood flow phenomena usually clinically measured...
December 2017: Cardiovascular Engineering and Technology
Yu Wang, Steven C Koenig, Michael A Sobieski, Mark S Slaughter, Guruprasad A Giridharan
Mechanical circulatory support (MCS) devices have become a standard therapy for heart failure (HF) patients. MCS device designs may differ by level of support, inflow and/or outflow cannulation sites, and mechanism(s) of cardiac unloading and blood flow delivery. Investigation and direct comparison of hemodynamic parameters that help characterize performance of MCS devices has been limited. We quantified cardiac and vascular hemodynamic responses for different types of MCS devices. Continuous flow (CF) left ventricular (LV) assist devices (LVAD) with LV or left atrial (LA) inlet, counterpulsation devices, percutaneous CF LVAD, and intra-aortic rotary blood pumps (IARBP) were quantified using established computer simulation and mock flow loop models...
December 2017: Cardiovascular Engineering and Technology
Yifan Wang, Annalisa Quaini, Sunčica Čanić, Marija Vukicevic, Stephen H Little
Mitral valve regurgitation (MR) is a disorder of the heart in which the mitral valve does not close properly. This causes an abnormal leaking of blood backwards from the left ventricle into the left atrium during the systolic contractions of the left ventricle. Noninvasive assessment of MR using echocardiography is an ongoing challenge. In particular, a major problem are eccentric or Coanda regurgitant jets which hug the walls of the left atrium and appear smaller in the color Doppler image of regurgitant flow...
December 2017: Cardiovascular Engineering and Technology
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