Browsing by Subject "coronary artery disease"
Now showing 1 - 3 of 3
- Results Per Page
- Sort Options
Item A Comparative Review of Screening, Consent, and Trial Visits and Follow-up Practices in Cardiovascular Dual Antiplatelet Therapy Drug, Device, and Registry Studies at Legacy Heart Center and The Heart Hospital Baylor Plano(2014-12-01) Mohiuddin, Ismail S.; Patricia A. Gwirtz; Rustin E. ReevesCoronary artery disease (CAD) is the number one cause of death in the United States and a large amount of research has been conducted to find the best treatment strategy to treat and prevent it. The PEGASUS-TIMI 54 study, a drug trial, the PzF SHIELD study, a device trial, and the TIGRIS study, a registry trial, build off of that research and are seeking novel strategies to improve patient outcomes There are significant differences between drug, device, and registry clinical research trials. Comparing these three dual antiplatelet research studies on the basis of screening, consent, and trial visits and follow-up practices gives insight into the distinct features of each kind of clinical research trial.Item Alterations in Beta-Adrenergic Receptor Density on Human Lymphocytes in Response to Chronic Exercise(2000-12-01) Brittain, Adam K.; Peter B. Raven; Stephen R. Grant; Michael W. MartinA number of cardiovascular adaptations have been shown to occur in healthy individuals as a result from regular, chronic exercise training. These changes include, but are not limited to, a lower resting heart rate, a lower heart rate at any given submaximal workload, an increase in stroke volume, an increase in maximal cardiac output due primarily to an increase in contractility, a decreased peripheral vascular resistance (increased peripheral vascular conductance), an overall increase in vascularity, an increase in left ventricular mass, and an increase in total body oxygen extraction (Raven, 1994). Some of these adaptations are also known to commonly occur in patients with coronary artery disease enabling them to increase their total work capacity. Therefore, exercise apparently adapts the heart to better cope with the adverse affects of coronary artery disease and helps to prevent the aforementioned disease from developing in healthy individuals. The beta-adrenergic receptor (β-AR) is essential for the activation of many aspects of the cardiovascular system during dynamic exercise (1). The catecholamines epinephrine and norepinephrine are released from the adrenal medulla and postganglionic fibers of the sympathetic nervous system respectively in response to dynamic exercise. Epinephrine and other beta-adrenergic receptor agonists bind and activate the β-AR on the cell membrane thus allowing it to couple with the stimulatory GTP-binding regulatory protein Gs. This step initiate the activation of adenylate cyclase and the synthesis of cyclic adenosine 3’,5’ monophosphate (cyclic AMP), a key intracellular second messenger. Cyclic AMP ultimately activates cyclic AMP-dependent protein kinase (PKA), an enzyme that phosphorylates a number of intracellular proteins that subsequently influence cell metabolism and function. Alterations in the activity of the adrenergic system seen in several clinical and physiological situations, including exercise, are directly associated with changes in lymphocytic β-AR density or function (2). Moreover, it has been suggested that the changes in receptor density on lymphocytes correlate closely with cardiovascular responsiveness to catecholamines in humans (3-6). Additionally, changes in catecholamine concentration within the physiological range have a regulatory effect on β-AR density and function (7). One particular study established an inverse relationship between plasma and urine catecholamine concentrations and lymphocytic β-AR density in man (8). It is the intent of this review to describe some of the cardiovascular adaptations that occur as a result of chronic exercise and how these changes could be caused by alterations in β-AR density and responsiveness. Additionally, the comparisons and contradictions between chronic heart failure and chronic exercise will be made. The role of the beta-adrenergic system in mediating the effects of exercise will be introduced. The structure of the β-AR will be described and how its molecular structure dictates its function. A brief synopsis will be presented on the mechanism in which β-AR operates subsequent to ligand binding. Alterations of the β-AR, particularly its expression in the heart, through transgenics will then be reviewed to show how this receptor could be responsive for some of the aforementioned adaptations to chronic exercise. In this, some of the differences between the β1- and β2-AR will be described as well as some of the therapeutic implications that could result from overexpression of the β-AR. Following this, alterations in the density of the β-AR after both short-term and long-term exposure to catecholamines will be examined. Included in this section with be the detailed description of the mechanism of receptor desensitization that precedes receptor down-regulation. A brief review will then be given on the effects of chronic exercise on β-AR density. The use of human lymphocytes as model cells will then be described. Binding theory will be explained as it will be the basis of methodology used in any subsequent studies. Along with this, [125 Iodo] cyanopindolol (125I-CYP) will be introduced and its advantages and disadvantages as a β-AR ligand probe will be discussed.Item Impact of age on technical and in-hospital outcomes of percutaneous coronary intervention for chronic total occlusions(2016-05-01) Iwnetu, Rahel; Patricia A. Gwirtz; Emmanouil S. Brilakis; Michael L. SmithBackground: We sought to examine the effect of patient age on the outcomes of percutaneous coronary intervention (PCI) of chronic total occlusions (CTO). Methods: We examined clinical and angiographic data as well as outcomes of 1,216 CTO PCIs performed in 1,195 patients divided into three age groups ([less than] 65, 65-75, and ≥75 years old). Results: Increasing age was associated with higher prevalence of prior stroke (7.6% vs 12.6% vs 17.2% for [less than] 65, 65-75, and ≥75 years old respectively, p [less than] 0.001) and prior coronary artery bypass graft surgery (25.2% vs 39.8% vs 45.5%, p [less than] 0.001), but lower prevalence of current smoking (36.4% vs 25.7% vs 14.6%, p [less than] 0.001). Older patients were also more likely to have hypertension (88.1% vs 88.7% vs 94.0%, p=0.042) and have moderately or severely calcified lesions (48.4% vs 59.8% vs 75.0%, p [less than] 0.001). Technical success rate was similar in all age groups (91.1% vs 90.7% vs 85.7%, p=0.054), but a higher incidence of major adverse cardiac events (MACE) was noted in the ≥75 years old group (0.9% vs 3.0% vs 5.1%, p=0.002), largely due to higher rate of cardiac tamponade requiring pericardiocentesis (0% vs 0.7% vs 2.2%, p=0.004). Procedure time, contrast volume and air kerma radiation dose did not differ significantly between the three groups. Conclusion: CTO PCI can be performed with high success rates among older patients, but may carry higher risk for complications in this patient group.