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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
641

A Multiple-Linear Regression Model to Predict Carotid Artery IMT in a Senior Population of Competitors at the Huntsman World Senior Games

Smith, Cheryl Ann 12 March 2012 (has links) (PDF)
Carotid intima-media thickness (cIMT) is a valid measure of cardiovascular disease (CVD). Physical activity appears to improve cIMT, however, research is inconclusive. This study investigated the relationship between physical activity (physical activity rating (PA-R)) and cardiovascular fitness (predicted VO2max , perceived functional ability (PFA)) and cIMT. Data collected from 341 seniors (≥50 years) competing in the Huntsman World Senior Games (HWSG) included blood lipids, inflammatory makers, blood glucose, blood pressure (BP) and anthropometric measurements of obesity and central adiposity. Multiple regression analysis was used to determine correlations of measured variables with cIMT. Two of the fitness related variables, PFA (r ≈ 0.1359; p = 0.012) and predicted VO2max (r ≈ 0.1475; p = 0.007) were significantly correlated to cIMT without controlling for confounding factors, but lost significance when adjustments for other CVD risk factors were included. PAR (r ≈ 0.0869; p = 0.111) was not significantly correlated to cIMT. Regression analysis indicated that the most predictive variables of cIMT we investigate were: age (t = 7.166, p = 0.000), gender (t = 3.310, p = 0.001), BMI (t = 1.892, p = 0.05), SBP (t = 3.952, p = 0.000), total cholesterol (TC) (t = 4.184, p = 0.000) and triglycerides (TRG) (t ≈ 3.466, p = 0.000), our R2 = .299, thus indicating these 6 variables account for about 30% of the variance in cIMT in seniors competing at HWSG. Physical activity and cardiovascular fitness influence other CVD risk factors and consequently may have an indirect impact on cIMT.
642

Comorbidities Predict Length of Stay Among Patients Admitted with Peripheral Artery Disease– An Analysis of The National Inpatient Sample.

Nriagu, Valentine C, MD, Annor, Eugene N, MD, Shaikh, Aamir-Ali, MPH, Karki, Arpana, BSc, Mamudu, Hadii M, PhD, Ahuja, Manik, PhD, Weierbach, Florence M, PhD, Husari, Ghaith H, PhD, Grant, Cori, PhD, Paul, Timir, MD, PhD 25 April 2023 (has links)
The global prevalence of peripheral artery disease (PAD) is estimated to be about 120 million, making up about 25.6% of the worldwide burden of cardiovascular diseases (CVD). In the United States (U.S.), the prevalence of PAD is about 7%, representing nearly 8 million adults. There is a higher prevalence of disease in Blacks and non-Hispanic Whites, with approximately 30% of Blacks and 20% of non-Hispanic Whites developing PAD in their lifetime. The strong risk factors associated with PAD include smoking, diabetes, hypertension, age, and male sex. Our study aimed to estimate the effects of obesity, alcohol abuse, renal failure, and hypertension on patients’ length of stay (LOS) among patients admitted with a diagnosis of PAD. Using the 2012 U.S. National Inpatient Sample database, we included 336,790 patients with PAD as a separate comorbidity during their index admission. Our main outcome variable was patients’ total length of stay (LOS) during the index admission. We categorized LOS < 1 into next day discharge (NDD) and LOS > 1 into non-NDD. Our predictor variables were hypertension, obesity, alcohol abuse and renal failure. We ran descriptive statistics to delineate the baseline characteristics of our sample population, and bivariate analysis with t-test and chi-square analysis. Multivariable logistic regression was used to estimate odds of non-NDD given our comorbidities; obesity, hypertension, alcohol abuse, renal failure while adjusting for age, race, and sex. We reported frequencies, p-values, and odd ratios (ORs) at a 95% significance level with alpha at 0.05. Of our final sample, 54.8% were males while 45.2% were females and the mean age of patients was 71.7 + 12.8. Hypertension, obesity, alcohol abuse and renal failure were present in 75%, 12%, 3.4%, and 30.9% of patients, respectively. Majority (75%) of the patients were white, while Black and Hispanic patients made up 13.3% and 7.1%, respectively. In our adjusted model, we found that patients with hypertension had 12% lower odds of non-NDD (OR = 0.88, CI= 0.86-0.90, P<0.0001) compared to those without hypertension, females had 20% increase in the odds of non-NDD compared to males (OR = 1.20, CI= 1.18-1.23, P<0.0001), patients with obesity, alcohol abuse and renal failure had 39%, 43% and 45% increase in odds of non-NDD compared to those without these comorbidities. (OR = 1.39, CI= 1.34-1.44, P<0.0001), (OR = 1.43, CI= 1.35-1.52, P<0.0001), (OR = 1.45, CI= 1.42-1.49, P<0.0001). Given the significant association between obesity, alcohol abuse, and renal failure with prolonged hospital stay in patients admitted to hospital with PAD, our study highlights the importance of adequate management of pre-existing patients' comorbidities. This is expected to improve overall length of stay and total healthcare utilization and costs, among patients with PAD.
643

Minimally Invasive Approach to Vascular Compression of The Duodenum

Ahmed, Aws E., Strand, Matthew S., Iannitti, David A. 25 April 2023 (has links)
Complete or partial obstruction of the duodenum by the superior mesenteric artery (SMA) is a rare cause of bowel obstruction. SMA syndrome results from the compression of the 3rd part of the duodenum between the superior mesenteric artery and the abdominal aorta. Causes include anatomical variation in the superior mesenteric artery, trauma, burns, surgeries, malignancy, and rapid weight loss. Diagnosis of SMA syndrome in patients may be difficult, as the clinical findings often resemble other forms of small bowel obstructions. This syndrome was first described in the literature by Carl Freiherr von Rokitansky in 1861. Subsequently, David Wilke provided a comprehensive description of the disease in a series of 75 patients. There has been skepticism about the existence of SMA syndrome due to scant literature reports and non-specific symptomatology. However, modern cross-sectional imaging has confirmed the existence of this rare syndrome. Here we present the case of a 50-year-old female with longstanding symptoms of gastrointestinal discomfort, weight loss, nausea, and vomiting. She underwent an exhaustive gastrointestinal workup until a diagnosis of SMA syndrome was made. We elected to proceed with a minimally invasive three-port laparoscopic, trans-mesenteric side-to-side duodenojejunostomy. The patient was discharged on postoperative day one after tolerating a regular diet. On one month follow-up, our patient reported improvement in symptoms with no postprandial pain or nausea and normal bowel movements. In conclusion, we report a case of superior mesenteric artery syndrome in a patient with recurrent abdominal pain and nausea. CT scan has the highest sensitivity for the diagnosis of SMA syndrome, findings suggestive of the diagnosis include an abnormal aortomesenteric angle and distance. While supplemental tube feeds and gastric drainage may resolve the condition without the need for surgery, this often takes many weeks to months to be effective. Minimally invasive surgical bypass is an attractive option because of the rapidity of symptom resolution, lack of need for long-term invasive tubes, short inpatient length of stay, and high success rate.
644

High frame rate imaging of arterial wall mechanics and blood flow dynamics for atherosclerosis diagnosis and monitoring

Karageorgos, Grigorios Marios January 2022 (has links)
Carotid artery wall stiffness has been widely considered as an index of vascular health, and has been associated with occurrence of cardiovascular events, such as stroke. In addition, the blood flow patterns in the carotid artery can yield crucial information on atherosclerosis progression and cerebrovascular impairment. Pulse wave imaging (PWI) is a non-invasive ultrasound imaging technique that tracks the propagation of the arterial pulse wave, providing thus regional arterial wall stiffness mapping. Moreover, towards enabling accurate visualization of blood flow patterns, ultrasound-based vector flow imaging (VFI) modalities have been developed. Building upon PWI and VFI techniques, the overall goal of this dissertation is to develop ultrasound-based methodologies that can provide simultaneous imaging of the carotid artery wall mechanics and blood flow dynamics at high temporal and spatial resolutions. The developed techniques are validated through vessel phantom experiments and simulations. Furthermore, their potential to diagnose pre-clinical stages of carotid artery disease and provide additional insights in risk for stroke assessment, is demonstrated in an atherosclerotic swine study and human subjects in vivo. More specifically: A method is presented that analyzes the pattern of arterial wall motion derived by PWI, in order to detect spatial mechanical inhomogeneity across an imaged artery, and provide piecewise arterial wall stiffness estimates. The proposed technique is validated in a phantom consisting of a soft and a stiff segment, while its feasibility is demonstrated to identify inhomogeneous wall properties in atherosclerotic human carotid arteries, as well as provide atherosclerotic plaque mechanical characterization in vivo. Subsequently, PWI is integrated with VFI techniques in the same ultrasound acquisition sequence, in order to enable simultaneous and co-localized imaging of arterial wall stiffness and blood vector flow velocity. The performance of the technique is investigated through experiments and FSI simulations. Moreover, its feasibility was shown to investigate associations between carotid artery Pulse Wave Velocity and blood flow patterns, in vivo. Based on the previously developed PWI and VFI modalities, a novel ultrasound-based technique is developed that combines high frame rate vector flow imaging with a data clustering approach, in order to enable direct and robust wall shear stress measurements. The performance of the proposed method is evaluated through vessel phantom experiments and simulations, while its feasibility is shown to detect pre-clinical stages of carotid artery disease in a swine model in vivo. In addition, a pilot clinical study is presented involving application of the developed modality in normal and atherosclerotic human carotid arteries in-vivo. Moving forward, the developed imaging modalities are used to implement novel clinical biomarkers based on carotid artery arterial wall mechanics and blood flow dynamics, that can potentially assist in risk for stroke assessment. The patterns of those biomarkers are investigated in the common carotid arteries of subjects with low degree of stenosis and medical history of stroke, against subjects without history of stroke. The same biomarkers are also analyzed with respect to stroke symptomatology in atherosclerotic patients with moderate to high degree of stenosis. Moreover, the developed techniques are used to identify vulnerable plaque components in subjects with fully developed plaques, as compared with CTA scans. Finally, a deep learning-based approach for motion tracking of the arterial wall throughout the cardiac cycle is proposed. A neural network is trained to learn the motion patterns of the carotid artery and potentially improve the quality of PWI. The performance of the technique is assessed in vessel phantom experiments and its feasibility is demonstrated in healthy human carotid arteries in-vivo.
645

Is Physical activity and effective tool to reduce depression after coronary artery event ? - A Systematic Review

ABIDI, SYED TAHA JAMIL January 2013 (has links)
Background: In most countries of the Western world there have been positive reductions in incidence of cardiovascular diseases in the past decades, among both men and women, but still mortality due to these disease groups are very high. Many studies about myocardial infarction have shown that depression after an event is related to poor medical outcomes from the disease. This means prolonged disability events of angina, arrhythmias, re-hospitalization and increased rate of mortality. In post myocardial infarction patients, depression is a major cause of both short and long term mortality. Aim: The aim of this study was to examine the scientific literature by a systematic review in order to find evidence based knowledge about the benefit of physical activity as a tool to reduce depression in patients with coronary artery event.Method: Three databases were searched (Pubmed, CINHAL, Cochrane) systematically and all articles that met inclusion criteria were examined and graded according to the criteria “Grading quality of evidence and strength of recommendations” by Atkins. A special protocol was designed further from AMSTAR by Beverley, for systematic review with and without the meta-analysis study. Results: It was evident that scientific reports fitting to the area was scarce showing that the area of interest was fairly new. Finally ten studies were included in this study, one meta-analysis, five randomized controlled trail and four clinical trials. The results showed low to moderate evidence for the use of high, moderate and low level of exercise as a tool to reduce depression in post coronary artery event patients.Conclusion: The following study concluded that, exercise shows positive effects to reduce the level of depression among coronary artery event patients.
646

Ticagrelor-Induced Diarrhea in a Patient With Acute Coronary Syndrome Requiring Percutaneous Coronary Artery Intervention

Alomari, Mohammad, Bratton, Hunter, Musmar, Ahmad, Al Momani, Laith A., Young, Mark 12 January 2019 (has links)
The P2Y inhibitor, ticagrelor, has been shown to prevent thrombotic events and hence, improve morbidity and mortality in patients with acute coronary syndrome following coronary artery stent placement. Despite many clinical benefits, ticagrelor has been associated with several adverse effects, including dyspnea, easy bruising, and gastrointestinal bleeding. We report the case of a 67-year-old patient with an acute coronary artery syndrome requiring percutaneous coronary artery intervention with stenting who developed ticagrelor-induced diarrhea. The patient's ticagrelor medication was replaced with clopidogrel, and his diarrhea completely resolved within one week with no complications observed at his one-month follow-up visit. Clinicians should be aware of this adverse effect of ticagrelor so as to guide them toward possible underlying etiologies and appropriate workup of chronic diarrhea.
647

Renal Artery Stenosis As Etiology of Recurrent Flash Pulmonary Edema and Role of Imaging in Timely Diagnosis and Management

Bhattad, Pradnya B., Jain, Vinay 09 April 2020 (has links)
Renal hypoperfusion from renal artery stenosis (RAS) activates the renin-angiotensin system, which in turn causes volume overload and hypertension. Atherosclerosis and fibromuscular dysplasia are the most common causes of renal artery stenosis. Recurrent flash pulmonary edema, also known as Pickering syndrome, is commonly associated with bilateral renal artery stenosis. There should be a high index of clinical suspicion for renal artery stenosis in the setting of recurrent flash pulmonary edema and severe hypertension in patients with atherosclerotic disease. Duplex ultrasonography is commonly recommended as the best initial test for the detection of renal artery stenosis. Computed tomography (CT) angiography (CTA) or magnetic resonance (MR) angiography (MRA) are useful diagnostic imaging studies for the detection of renal artery stenosis in patients where duplex ultrasonography is difficult. If duplex ultrasound, CTA, and MRA are indeterminate or pose a risk of significant renal impairment, renal angiography is useful for a definitive diagnosis of RAS. The focus of medical management for RAS relies on controlling renovascular hypertension and aggressive lifestyle modification with control of atherosclerotic disease risk factors. The restoration of renal artery patency by revascularization in the setting of RAS due to atherosclerosis may help in the management of hypertension and minimize renal dysfunction.
648

Assessing the Long-term Patency and Clinical Outcomes of Venous and Arterial Grafts Used in Coronary Artery Bypass Grafting: A Meta-analysis

Waheed, Abdul, Klosterman, Emily, Lee, Joseph, Mishra, Ankita, Narasimha, Vijay, Tuma, Faiz, Bokhari, Faran, Haq, Furqan, Misra, Subhasis 16 September 2019 (has links)
Introduction The long-term patency of the grafts used during the coronary artery bypass grafting (CABG) is one of the most significant predictors of the clinical outcomes. The gold standard graft used during CABG with the best long-term patency rate and the better clinical outcomes is left internal thoracic artery (LITA) grafted to the left coronary artery (LCA). The controversy lies in choosing the second-best conduit for the non-left coronary artery (NLCA) with similar patency rate as LITA. This meta-analysis examines the long-term patency and clinical outcomes of all arterial grafts versus all venous grafts used during the CABG. Methods A comprehensive literature search of all published randomized control trials (RCTs) assessing long-term patency and clinical outcomes of grafts used in CABG was conducted using PubMed, Cochrane Central Registry of Controlled Trials, and Google Scholar (1966-2018). Keywords searched included combinations of "CABG", "venous grafts in CABG", "arterial grafts in CABG", "radial artery grafts in CABG", "gastroepiploic artery grafts in CABG", "patency and clinical outcomes". Inclusion criteria included: RCTs comparing the long-term patency, and clinical outcomes of radial artery, right internal thoracic artery, gastroduodenal artery, and saphenous vein grafts used in CABG. Long-term patency of the grafts and clinical outcomes were analyzed. Results Eight RCTs involving 2,091 patients with 1,164 patients receiving arterial grafts and 927 patients receiving venous grafts were included. There was no difference between the long-term patency rate (relative risk (RR) = 1.050, 95% confidence interval (CI) = 0.949 to 1.162, and p = 0.344), overall mortality rate (RR = 1.095, 95% CI = 0.561 to 2.136, and p = 0.790), rate of myocardial infarction (MI) (RR = 0.860, 95% CI = 0.409 to 1.812, and P = 0.692), and re-intervention rate (RR = 0.0768, 95% CI = 0.419 to 1.406, and P = 0.392) between arterial and venous grafts. Conclusion The use of arterial conduits over the venous conduits has no significant superiority regarding the long-term graft patency, the rate of MI, overall mortality, and the rate of revascularization following CABG. Additional adequately powered studies are needed to further evaluate the long-term outcomes of arterial and venous grafts following the CABG.
649

Fluid Flow Characterization in Rapid Prototyped Common Iliac Artery Aneurysm Molds

Greinke, Daniel Cole 01 March 2016 (has links) (PDF)
The goal of this project was to determine whether i) fused deposition modeling could be employed to manufacture molds for vascular constructs, ii) whether vascular constructs could be created from these molds, and iii) to verify practical equivalence between observed fluid velocities. Dye tracking was to be employed to characterize fluid velocity profiles through the in vitro vascular constructs, including a half-vessel model and a full vessel model of an iliac artery aneurysm. A PDMS half-vessel construct was manufactured, and the movement of dye through the construct was tracked by a cellphone camera. Thresholds were applied to each video in HSB or YUV mode in ImageJ, and analyzed to determine the velocity of the fluid through the construct. COMSOL simulations of the half-vessel were conducted for comparison to the empirical observations. Plots describing the flow velocities along the maximum streamline path length were generated, and a one sample t-test was conducted at a 5% significance level to determine whether there was a significant difference between velocity values obtained by dye tracking and the COMSOL simulations. It was determined that the empirical dye tracking trials failed to demonstrate agreement between the measured and predicted flow rates. A full vessel construct was not completed due to unforeseen time constraints. Dye tracking was not determined to be reliable as a means of measuring the maximum velocity of fluid. Discrepancies between the empirical observations and the COMSOL simulation are discussed. The discrepancy was attributed to limitations in the experimental protocol; low frame rate, poor control over lighting conditions, and the subjectivity involved in image processing. Methods of improving upon the manufacturing and experimental protocols used for the half-vessel are proposed for future work, such as improving control over lighting conditions, choosing a camera with a higher frame rate, constructing a more stable fixture, exploring PIV. Additionally, the technical problems leading to the failure to complete the full vessel model are discussed, and changes in the manufacturing process are proposed to allow dissolution or removal of the aneurysm model.
650

The Effect of Artery Bifurcation Angles on Fluid Flow and Wall Shear Stress in the Middle Cerebral Artery

Jones, Zachary Ramey 01 December 2014 (has links) (PDF)
Saccular aneurysms are the abnormal plastic deformation of veins and arteries that can lead to lethal thrombus genesis or internal hemorrhaging. Medication and surgery greatly reduce the mortality rates, but treatment is limited by predicting who will develop aneurysms. A common location for saccular aneurysm genesis is at the main middle cerebral artery (MCA) bifurcation. The main MCA bifurcation is comprised of the M1 MCA segment, parent artery, and two M2 segments, daughter arteries. Studies have found that the lateral angle (LA) ratio of the MCA bifurcation is correlated with aneurysm formation. The LA ratio is defined as the angle between the M1 and the larger M2 divided by the angle between the M1 and the smaller M2. When the LA ratio is equal to 1, perfectly symmetrical, no aneurysms are found at the MCA bifurcation. When the LA ratio is greater than 1.6, aneurysms are commonly found at the MCA bifurcation. In the research described here, varying MCA bifurcation angles were compared to uncover any changes to fluid flow and wall shear stress that could stimulate aneurysm growth. Eight pre-aneurysm MCA bifurcation models were created in SolidWorks® using 120 degrees, 90 degrees, and 60 degrees as the angle between the M1 and the larger M2. LA ratios of 1, 1.6 and 2.2 were then used to characterize the other branch angle (60 degrees with a LA ratio of 1 was excluded). These models were imported into COMSOL Multiphysics® where the laminar fluid flow module was used to simulate non-Newtonian blood flow. Fluid flow profiles showed little to no change between the models. Shear stress changed when the LA ratio was increased, but the changed varied between the 120, 90 and 60 degree models. 120 degree models had a 3.87% decrease in max shear stress with a LA ratio of 2.2 while the 90 degree models had 7.5% decrease in max shear stress with a LA ratio of 2.2. Each daughter artery had distinct areas of high shear stress when the LA ratio equaled 1. Increasing the LA ratio or decreasing the bifurcation angle caused the areas of shear stress to merge together. Increasing LA ratio caused shear stress to decrease and spread around the MCA bifurcation. The reduction in max wall shear stress for high LA ratios supports current aneurysm genesis hypothesizes, but additional testing is required before bifurcation geometries can be used to predicted aneurysm genesis.

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