Browsing by Subject "Cardiovascular"

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    Assessment of capped-end pulsation method for measuring pulse wave velocity
    (2024) Do, Joshua
    Cardiovascular disease is a growing epidemic in the U.S. and worldwide. As more and more individuals suffer from complications from poor cardiovascular function, there is a growing need for early diagnostic modalities. Vessel stiffness is a common biomarker to assess vascular health. For example, atherosclerosis caused by plaque formation can cause vessels to stiffen. For obvious reasons, it is not reasonable to take out an arterial sample to mechanically test for stiffness. Thus, there is a need for a non-invasive way to measure stiffness. Described by the Moens-Korteweg equation, pulse wave velocity (PWV) is non-linearly proportional to the stiffness of the vessel. Therefore, this equation provides a mechanism in which stiffness can be measured non-invasively. Because of its ease of measurement as well as efficacy, PWV has become a gold standard in assessing vascular health. Commonly, the time delay in pulse pressures taken at the carotid and femoral arteries is used as quick way to assess aortic health. Unfortunately, this method is not standardized and variations between populations could affect this measurement. Additionally, in clinical practice, PWV is only a measure of the average wave speed through a person’s aorta. As such, it doesn’t provide any local measurements along the arterial tree. Current measuring techniques, such as tonometry and ultrasound, struggle to achieve the resolution needed to make localized measurements. Additionally, different geometries along the vessels, such as curvature and bifurcations, can cause reflections and affect wave speed. All these variables are difficult to control for in vivo. As such, ex vivo experimentation with the aim of studying how wave speed is affected by these variables, is an attractive alternative. In an ex vivo setting, there are more tools available to achieve the resolution needed to make local measurements. Just like in vivo, ex vivo experiments need to overcome two main challenges: 1) achieve the resolution needed capture the speed of a wave and 2) control wave reflections. To address both issues, our group proposes that capping the end of a vessel while sending periodic pulse waves can solve both problems simultaneously. By embracing wave reflections off the capped end, we reduce that issue down to a problem that is well-behaved and understood. Additionally, the interference pattern caused by the incoming and reflected waves has the potential to create a standing wave. Because the shape of a standing wave is time-invariant, temporal resolution becomes less of an issue. By knowing the wavelength of the standing wave as well as the forcing frequency, one could calculate the wave speed.
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    Cardiovascular Health and Occupational Stress in Police Officers
    (2018-05) Betker, Morgan
    Police officers have a higher incidence of disease and mortality rates when compared to the general population. Few studies have examined the link between lifestyle factors, occupational stressors and physiological dysfunction and how these factors lead to disease progression among police officers. The purpose of this dissertation was to examine the impact of physical fitness, lifestyle and occupational factors, perceived stressors, and sleep quality on various aspects of police officer physical, physiological and psychological health. Specifically, police officers (n = 116) completed several testing methods, both in the lab and field-based settings, assessing physical, physiological and psychological health. The first aim was to understand the influence of lifestyle and occupational factors on cardiovascular fitness and autonomic nervous system function among police officers. Not surprisingly, results indicated that officers who engage in regular exercise and have a low body fat also have higher aerobic fitness. There was not a significant relationship between heart rate variability indices and other lifestyle or occupational factors. The secondary aim was to examine the effect of perceived work stress on physiological biomarker expression for cardiovascular health. Results indicated that high scores on the Police Occupational Stress Survey (POSS) were related to higher pro-inflammatory cytokines (C-reactive protein (CRP) and tumor necrosis factor alpha (TNFα)). Finally, the purpose of the third aim was to examine the effect of sleep quality and shift-work on physiological biomarker expression in association with cardiovascular health. Contrary to what was hypothesized, day-time officers had higher levels of cortisol and total cholesterol expression than middle- or night-shift officers. In conclusion, poor lifestyle choices, unmanaged stressors, and constantly rotating shift schedules may contribute to increased allostatic load which can contribute to early, all-cause mortality among police officers. Future studies are needed that further examine cardiovascular health, sources of perceived stress, and sleep disturbances. Additionally, future research should examine the efficacy of interventions that address psychosocial factors and cardiovascular fitness among police officers.