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Numerical Simulation And Experimentation Of Pulsatile Flows In Axisymmetric Arterial Models, Tadesse Gebreegziabher

Wayne State University Dissertations

ABSTRACT

NUMERICAL SIMULATION AND EXPERIMENTATION OF PULSATILE FLOWS IN AXISYMMETRIC ARTERIAL MODELS

by

TADESSE GEBREEGZIABHER

December 2011

Co-advisors: 1. Dr. Emmanuel Ayorinde 2. Dr. Trilochan Singh

Major: Mechanical Engineering

Degree: Doctor of Philosophy

The primary motivation for this dissertation is the fluid flow and structural response to unsteady blood flow in the human body. The research work is a synergistic merging of numerical simulation and experimentation. For the experiments, an all-encompassing, highly flexible experimental apparatus was designed and fabricated to facilitate a wide range of operating conditions, the range of which was chosen to accommodate mammalian cardiovascular system for both …

Examining The Relationships Among Injury Outcomes, Velocity And Grip Strength During Dynamic Platform Perturbation, Braden Cripe

Master's Theses (2009 -)

Studies examining the relationship between inputs and outputs for simulated models of dynamically perturbed horizontal platforms are scarce. Most of these scenarios include a standing operator with upper extremity grip, oftentimes subjected to lateral impulses, which may lead to occupant injury. While the detailed study of these collision scenarios is sparse, the prevalence of their application is great.

This thesis aims to identify how two input parameters, velocity change (ÄV) and grip strength, affect injury assessment reference values (IARVs). This is accomplished by using Mathematical Dynamic Modeling (MADYMO) software to simulate the scenarios defined by those inputs. In the simulation, …

Ischemia Impairs Vasodilation In Skeletal Muscle Resistance Artery, Kyle Remington Struthers

Master's Theses

Functional vasodilation in arterioles is impaired with chronic ischemia. We sought to examine the impact of chronic ischemia and age on skeletal muscle resistance artery function. To examine the impact of chronic ischemia, the femoral artery was resected from young (2-3mo) and adult (6-7mo) mice and the profunda femoris artery diameter was measured at rest and following gracilis muscle contraction 14 days later using intravital microscopy. Functional vasodilation was significantly impaired in ischemic mice (14.4±4.6% vs. 137.8±14.3%, p<0.0001 n=8) and non-ischemic adult mice (103.0±9.4% vs. 137.8±14.3%, p=0.05 n=10). In order to analyze the cellular mechanisms of the impairment, a protocol was developed to apply pharmacological agents to the experimental preparation while maintaining tissue homeostasis. Endothelial and smooth muscle dependent vasodilation were impaired with ischemia, 39.6 ± 13.6% vs. 80.5 ± 11.4% and 43.0 ± 11.7% vs. 85.1 ± 10.5%, respectively. From this data, it can be supported that smooth muscle dysfunction is the reason for the observed impairment in arterial vasodilation.

Characterization And Implementation Of A Decellularized Porcine Vessel As A Biologic Scaffold For A Blood Vessel Mimic, Aubrey N. Smith

Master's Theses

Every 34 seconds, someone in the United States suffers from a heart attack.  Most heart attacks are caused by atherosclerotic build up in the coronary arteries, occluding normal blood flow.  Balloon angioplasty procedures in combination with a metal stent often result in successful restoration of normal blood flow.  However, bare metal stents often lead to restenosis and other complications.  To compensate for this problem, industry has created drug-eluting stents to promote healing of the artery wall post stenting.  These stents are continually advancing toward better drug-eluting designs and methods, resulting in a need for fast and reliable pre-clinical testing modalities. …

Exploring The Potential Of Inkjet Printing For The Fabrication Of Tissue Test Systems, Vidya Seshadri

All Theses

Animal models and two-dimensional assays involved in drug testing, vaccine development and basic scientific discovery are not an accurate representation of the human body; hence there is a need to develop new bench top methodologies which are better suited to yield information about in vivo behavior. There is a paucity of reliable in vitro-derived information regarding the reasons for the cause and progression of diseases. These concerns have lead to the development of three-dimensional systems which can facilitate improved understanding of disease etiology and also can bridge the path to the clinic.
The long term goal, beyond the scope of …

Investigation Of Variability In Cognitive State Assessment Based On Electroencephalogram-Derived Features, Samantha Lokelani Crossen

Browse all Theses and Dissertations

To implement adaptive aiding in modern aviation systems there is a need for accurate and reliable classification of cognitive workload. Using electroencephalogram (EEG)-derived features, it has been reported that an Artificial Neural Network (ANN) can achieve 95% or higher classification accuracy on the same day for an individual operator, but only 70% or less on a different day. To gain a further insight into this discrepancy, data from a previous study was utilized to study the classification variability. The EEG-derived features were first calculated by spectral power estimation. The variability was then analyzed by performing cognitive workload classification in which …

Surface Morphology Of Platelet Adhesion Influenced By Activators, Inhibitors And Shear Stress, Melanie Groan Watson

Doctoral Dissertations

Platelet activation involves multiple events, one of which is the generation and release of nitric oxide (NO), a platelet aggregation inhibitor. Platelets simultaneously send and receive various agents that promote a positive and negative feedback control system during hemostasis. Although the purpose of platelet-derived NO is not fully understood, NO is known to inhibit platelet recruitment. NO's relatively large diffusion coefficient allows it to diffuse more rapidly than platelet agonists. It may thus be able to inhibit recruitment of platelets near the periphery of a growing thrombus before agonists have substantially accumulated in those regions.

Results from two studies in …

In Vitro Evaluation Of Mechanical Heart Valve Performance Using A Novel Test Chamber In An Automated Mock Circulatory Loop, Antonio Walker

Theses and Dissertations

Valvular heart disease (VHD) continues to have significant effects on many people’s lives, with numbers expected to grow tremendously over the next few years. Individuals suffering from severe valvular heart disease usually require a heart valve transplant in order to restore the native valve’s vital unidirectional flow regulation. Therefore, artificial heart valve (AHV) research is of very high importance. Previous research studies have provided substantial input in the realm of AHV design relative to durability, thrombotic and hemolytic potential, and overall functionality. However, modifications continue to be warranted due to limitations in the accuracy and time efficiency of the in …

Implementation Of Physiologic Pressure Conditions In A Blood Vessel Mimic Bioreactor System, Kevin Mark Okarski

Master's Theses

ABSTRACT

Implementation of Physiologic Pressure Conditions in a Blood Vessel Mimic Bioreactor System

Kevin Mark Okarski

Tissue engineering has traditionally been pursued as a therapeutic science intended for restoring or replacing diseased or damaged biologic tissues or organs. Cal Poly’s Blood Vessel Mimic Laboratory is developing a novel application of tissue engineering as a tool for the preclinical evaluation of intravascular devices. The blood vessel mimic (BVM) system has been previously used to assess the tissue response to deployed stents, but under non-physiologic conditions. Since then, efforts have been made to improve the vessel and bioreactor’s ability to emulate in …

Finite Element Modeling Of Icd Lead Silicone Soft-Tips, Jose J. Lepe

Master's Theses

Although highly underutilized by the medical device industry, Finite Element Analysis (FEA) in the development of new technologies is gaining popularity as regulatory bodies such as the Food and Drug Administration (FDA) begin to require additional proof of safety through scientific methods. Non-linear FEA allows engineers to realistically simulate the mechanical behavior of implants as seen in the in-vitro, or in some cases, the in-vivo configurations. The work presented in this report investigates how computational methods can be used to simulate the interaction of a St. Jude Medical silicone soft-tip as it passes through a Peel-Away Sheath (i.e. introducer). In …

Development Of A Device For Whole Body Stimulation Of The Otoliths, Jon Edward Weimer

Theses

Over the past few decades, research has been conducted to explore the effects of microgravity on human musculature, As seen in astronauts upon their return to Earth after prolonged spaceflight, extensive muscle atrophy due to adaptation to conditions of microgravity many times decreases a person's ability to walk or even stand, With an understanding of the anatomical mechanisms that provide postural control, the proper stimulation, resulting in a reduction in spasticity, could be provided by simulating these conditions of microgravity.

In order to simulate microgravity, a device has been developed that is capable of providing whole body stimulation of the …

On Coupling A Lumped Parameter Heart Model And A Three-Dimensional Finite Element Aorta Model, H. J. Kim, Irene E. Vignon-Clementel, C. A. Figueroa, John F. Ladisa, K. E. Jansen, Jeffrey A. Feinstein, Charles A. Taylor

Biomedical Engineering Faculty Research and Publications

Aortic flow and pressure result from the interactions between the heart and arterial system. In this work, we considered these interactions by utilizing a lumped parameter heart model as an inflow boundary condition for three-dimensional finite element simulations of aortic blood flow and vessel wall dynamics. The ventricular pressure–volume behavior of the lumped parameter heart model is approximated using a time varying elastance function scaled from a normalized elastance function. When the aortic valve is open, the coupled multidomain method is used to strongly couple the lumped parameter heart model and three-dimensional arterial models and compute ventricular volume, ventricular pressure, …

A Rapid Prototyping Method For Constructing A Complex Three-Dimensional Substrate, Kathryn Jacoba Hart

Master's Theses

Cell culturing on three-dimensional structures has increased the possibilities in tissue engineering and bioreactor research. These structures enable cells to differentiate, proliferate, mobilize, and function in a conformation that more accurately mimics in vivo conditions. Computer generated models aid in development and rapid alteration of three-dimensional cell substrates, defining their internal structure as well as their external morphology. The rapid transition from substrate design to a viable culture is imperative to quickly advance research in biomedical and tissue engineering applications.

The aim of this thesis is to investigate the feasibility of a rapid prototyping process by selectively cross-linking and assembling …

Time-Frequency Analysis Of Intracardiac Electrogram, Erik Brockman

Master's Theses

The Cardiac Rhythm Management Division of St. Jude Medical specializes in the development of implantable cardioverter defibrillators that improve the quality of life for patients diagnosed with a variety of cardiac arrhythmias, especially for patients prone to sudden cardiac death. With the goal to improve detection of cardiac arrhythmias, this study explored the value in time-frequency analysis of intracardiac electrogram in four steps. The first two steps characterized, in the frequency domain, the waveforms that construct the cardiac cycle. The third step developed a new algorithm that putatively provides the least computationally expensive way to identifying cardiac waveforms in the …

Preparation For Nerve Membrane Potential Readings Of A Leech, Laboratory Setup And Dissection Process, Jason Patrick Caulfield

Master's Theses

A well documented laboratory setup, leech preparation process, and bio-potential data recording process are needed. Repeatability and quality data recordings are essential and thus dictate the requirements of the laboratory setup and processes listed above. Advances in technology have both helped and hindered this development. While very precise equipment is required to record the low voltage bio-potentials, noisy electronic equipment and wires surrounding the work area provide high levels of interference. Proper laboratory setup and data recording processes, however, limit the unwanted interference. Quality data can only be recorded from a properly handled and prepared leech subject. Proper setup and …

Preparation And Characterization Of Electrospun Poly(D, L-Lactide-Co-Glycolide) Scaffolds For Vascular Tissue Engineering And The Advancement Of An In Vitro Blood Vessel Mimic, Tiffany Richelle Pena

Master's Theses

PREPARATION AND CHARACTERIZATION OF ELECTROSPUN POLY(D,L-LACTIDE-CO-GLYCOLIDE) SCAFFFOLDS FOR VASCULAR TISSUE ENGINEERING AND THE ADVANCEMENT OF AN IN VITRO BLOOD VESSEL MIMIC

Tiffany Richelle Peña

Currently, an estimated 1 in every 3 adult Americans are affected by one or more cardiovascular complications. The most common complication is coronary artery disease, specifically atherosclerosis. Outcomes of balloon angioplasty treatments have been significantly improved with the addition of drug eluting stents to the process. Although both bare metal and drug eluting stents have greatly increased the effectiveness of angioplasty and decreased the occurrence of restenosis, several complications still exist. For this reason, the stent …

Analytical Modeling With Decoupled Optimal Control Of Biomechanical Sit -To -Stand Movement, Asif Mahmood Mughal

Theses and Dissertations

Biomechanical movements with multiple degrees of freedom exhibit complex coordination and control mechanisms in the presence of physiological constraints. A human body biomechanical model which can mimic diverse 3D physiological movements is a challenging task. In this study, we develop a mathematical framework to study human sit-to-stand (STS) movement using 2D biomechanical models. This analytical framework models the physiological system for feedback controller design. A 2D 4-segment biomechanical model with optimal feedback controller design provides a motivation to extend this scheme for analytical 3D bipedal modeling. We used a newly developed mathematical modeling toolbox (Maple’s DynaFlexPro) to generate 3D 8-segment …

Central And Peripheral Autonomic Influences : Analysis Of Cardio-Pulmonary Dynamics Using Novel Wavelet Statistical Methods, Anne Marie Petrock

Dissertations

The development and implementation of novel signal processing techniques, particularly with regard to applications in the clinical environment, is critical to bringing computer-aided diagnoses of disease to reality. One of the most confounding factors in the field of cardiac autonomic response (CAR) research is the influence of the coupling of respiratory oscillations with cardiac oscillations.

This research had three objectives. The first was the assessment of central autonomic influence over heart rate oscillations when the pulmonary system is damaged. The second was to assess the link between peripheral and central autonomic control schema by evaluating the heart rate variability (HRV) …

Design Of Near-Optimal Waveforms For Chest And Abdominal Compression And Decompression In Cpr Using Computer-Simulated Evolution, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Objective: To discover design principles underlying the optimal waveforms for external chest and abdominal compression and decompression during cardiac arrest and CPR. Method: A 14-compartment mathematical model of the human cardiopulmonary system is used to test successive generations of randomly mutated external compression waveforms during cardiac arrest and resuscitation. Mutated waveforms that produced superior mean perfusion pressure became parents for the next generation. Selection was based upon either systemic perfusion pressure (SPP=thoracic aortic minus right atrial pressure) or upon coronary perfusion pressure (CPP=thoracic aortic pressure minus myocardial wall pressure). After simulations of 64,414 individual CPR episodes, 40 highly evolved waveforms …

Synthesising Life-Sciences And Control Engineering: An Outline Survey And A Practical Example, Aidan O'Dwyer

Conference papers

There is an increasing interest in life science related areas in the electrical and control engineering community [1]. One manifestation of this interest is the development of interdisciplinary programmes, such as the B.Sc. in Medical Physics and Bioengineering, offered by the Dublin Institute of Technology from September 2005. A significant amount of research work in control engineering has focused on aspects of human physiological system, for example blood glucose regulation [2], cardiovascular modelling and control [3], and limb control [4]. There is an increasing emphasis on interdisciplinary research; in recognition of this, the Institute of Electrical Engineers (IEE) has starting …

Multifractal Analysis Of Heart Rate Variability Using Wavelet-Transform Modulus-Maxima Method, Chirag Jani

Theses

Physiological signals are complex and carry information of human health. Recent studies reveal that under normal conditions, the heart rate time series shows multifractal behavior. In contrast, HRV in the pathological state such as congestive heart failure exhibits more monofractal-like structure. Recent advances in the assessment of heart rate variability (HRV) uses a nonlinear dynamics approach. In this study, the main objective is to use the wavelet-transform modulus-maxima method for the multifractal analysis of the heart rate time senes.

The degree of the multifractality is defined by the singularities (a point in time series where a mathematical function is not …

Effects Of An Impedance Threshold Valve Upon Hemodynamics In Standard Cpr: Studies In A Refined Computational Model, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

An impedance threshold valve (ITV) is a new airway adjunct for resuscitation that permits generation of a small vacuum in the chest during the recoil phase of chest compression. Objectives: To explore in detail the expected magnitude and the hemodynamic mechanisms of circulatory augmentation by an ITV in standard CPR. Method: A 14-compartment mathematical model of the human cardiopulmonary system—upgraded to include applied chest compression force, elastic recoil of the chest wall, anatomic details of the heart and lungs, and the biomechanics of mediastinal compression—is exercised to explore the conditions required for circulatory augmentation by an ITV during various modes …

Relative Effectiveness Of Interposed Abdominal Compression Cpr: Sensitivity Analysis And Recommended Compression Rates, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

Interposed abdominal compression (IAC)-CPR incorporates alternating chest and abdominal compressions to generate enhanced artificial circulation during cardiac arrest. The technique has been generally successful in improving blood flow and survival compared to standard CPR; however some questions remain. Objective: To determine "why does IAC-CPR produce more apparent benefit in some subjects than in others? and "what is the proper compression rate, given that there are actually two compressions (chest and abdomen) in each cycle?" Method: Computer models provide a means to search for subtle effects in complex systems. The present study employs a validated 12-compartment mathematical model of the human …

Effects Of Sleep Deprivation On Autonomic Nervous System, Jaeyeaon Cho

Theses

Sleep deprivation (SD) has been thought a potential factor to trigger cardiovascular events by increasing the sympathetic nervous system activity. The aim of the present study was to evaluate the relationship between sleep deprivation and the autonomic nervous system activity by means of heart rate variability (HRV) and blood pressure variability (BPV). All data were acquired in the sleep lab of Columbia University.

Data were acquired from the two groups, SD and control. Subjects in the SD group did not sleep for thirty-six hours but subjects in the control group slept at night as usual. There were five different data …

Transmission Of Light And Audible Sound In A Synthetic Fog Medium, Bhavin Babaria

Theses

The primary goal of the thesis was to study the propagation of visible light and auditory sound through a synthetic fog medium compared to an ambient air environment. It is known that the fog substantially decreases the visibility however; this has not been studied quantitatively. Further information regarding other energies such as sound is also needed to understand how the energy reacts in the fog medium. The extent of visual and auditory degradation in humans needs to be investigated. Researchers have studied light transmitted through water, air; however, no one has studied how light or sound is transmitted through a …

Investigation Of Heart Rate Variability During Sleep Apnea, Sekar Subramanian

Theses

Sleep apnea is a disorder, where there are repetitive pauses in respiratory flow of at least 10 seconds or longer duration, and which occur more than five times per hour. Apnea has strong modulating effects on the autonomic nervous system, with prominent heart rate variation. It can be assumed that during sleep, internal influences (sympathetic and parasympathetic nervous system activities) dominate the autonomic nervous system; in addition repetitive apneas are accompanied by a pronounced increase in average heart rate. The aim of this study was to investigate the heart rate variability using spectral analysis and time-frequency analysis during sleep apnea. …

Loss Of Sympathetic Control Of Cardiovascular Function Following Spinal Cord Injury, Charles Everett Hogancamp Ii

University of Kentucky Master's Theses

Cardiovascular control in the human is significantly impaired after spinal cord injury(SCI) having a direct effect on the sympathetic nervous system (SNS) causing an inability toregulate vasoconstriction below the level of the lesion. The effects of SCI on the two majorcomponents of blood pressure regulation, control of plasma volume and neural control of theheart and peripheral vasculature are poorly understood. In particular, no index to diagnosedisorders to autonomic control of the heart and vasculature has been developed. The presentstudy primarily utilized noninvasively acquired, easily accessible variables that may havepromise as indicators of autonomic activity for assessing the level of autonomic …

Histologic Evaluation Of The Efficacy Of Rhbmp-2 Compared With Autograft Bone In Sheep Spinal Anterior Interbody Fusion, Harvinder Sandhu, Jeffrey M. Toth, Ashish Diwan, H. B. Seim Iii, Linda E.A. Kanim, J. Michael Kabo, A. Simon Turner

Biomedical Engineering Faculty Research and Publications

Study Design. The sheep anterior lumbar spinal fusion model was used to study the efficacy of recombinant human bone morphogenetic protein-2 (rhBMP-2)–collagen composite in comparison with autograft to enhance spinal interbody fusion. Comparisons were drawn from temporal radiographic and end-point biomechanical and histologic data.

Objective. To analyze histologically the ability of rhBMP-2 to achieve complete arthrodesis between vertebral bodies.

Summary of Background Data. Studies using rhBMP for enhancement of anterior interbody fusion have used numerous endpoints. However, systematic histologic evaluation of the fusion has not been conducted.

Methods. Twelve sheep underwent single-level anterior lumbar interbody fusion performed with a cylindrical …

Effect Of Postural Tilt On The Autonomic Nervous System In Gulf War Veterans, Shrenik Dagli

Theses

Time-frequency signal representations characterize signals over a joint time-frequency plane. They combine time-domain and frequency-domain analysis to yield a potentially more revealing picture of the temporal localization of a signal spectrum. Time-frequency distributions (TFDS) of signals map a one-dimensional function of time, x (t), into a two-dimensional function of time and frequency, p(t, f). Most TFDs are "time-varying representations' which are similar conceptually to a musical score with time running along one axis and frequency along the other axis.

Many Gulf War Veterans complained of symptoms like unexplainable tiredness. This condition is known as the Gulf War Syndrome. The purpose …

Role Of Sympathovagal Imbalance In Syncope Using Heart Rate Variability Analysis, Jayadeep Krishnah Unni

Theses

One of the common and challenging problems confronting the physician in clinical practice is recurrent syncope. Despite extensive evaluations, the causes of these cases Of syncope are not found in more than 40% of the patients.

It is thought that most patients who experience unexplained syncope do so because of transient, unpredictable episodes of vasovagally mediated hypotension and bradycardia. It is hypothesized that impaired inhibition of parasympathetic tone during stress accompanies the development of syncope. Head-up tilt table testing reportedly provokes vasovagal episodes effectively in susceptible persons.

This study attempts to explain the role played by the sympathetic and parasympathetic …