Cardiovascular disease (CVD) is the leading cause of death in the United States. Analysis of vascular reactivity (VR) in response to brachial artery occlusion is used to estimate arterial health and to determine the likelihood of future cardiovascular complications. Development of a sensitive technique to assess VR is fundamental to the field of preventive cardiology. The conventional technique to study VR is by monitoring arterial diameter changes during hyperemia following occlusion using ultrasound based methods. Such measurements require highly qualified technicians and expensive equipment; and are complicated by signal noise introduced by motion and posture among others. It is well known that tissue temperature changes are a direct response to variations in blood flow, and it has been observed in small clinical studies that variations in fingertip temperature during brachial artery occlusion and subsequent hyperemia is a simple surrogate for the measurement of vascular reactivity and endothelial dysfunction. Given the promising nature of thermal monitoring to study VR, this thesis focuses on the analysis of the underlying physics affecting fingertip temperature during vascular occlusion and subsequent hyperemia. I will quantify the contribution of hemodynamic, anatomical and environmental factors over digit temperature changes, which will serve to determine the sensitivity of the digital thermal monitoring (DTM) technique. I have quantified the effect of several contributing factors to fingertip temperature and DTM results. The aims of this thesis focus on: (1) creation of a mathematical model of heat transfer at baseline, during, and after a reactive hyperemia test; and (2) validation of the model and experimental analysis of thermal and flow parameters in healthy volunteers. The proposed project is an innovative study that intends to show and quantify the relationship between VR and digital thermal reactivity, translating mathematical models based on the physics of heat transfer and fluid mechanics to clinical application. The parametric studies performed with the zeroth order model served to separate the contribution of environment and blood flow over the temperature curves measured during brachial artery occlusion. The thermal models developed were able to reproduce the trend of the temperature response observed experimentally at the fingertip.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2006. / Härtill 5 uppsatser.

Thesis (Ph. D.)--University of Oregon, 2005. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 195-207). Also available for download via the World Wide Web; free to University of Oregon users.

xvii, 168 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / An acute bout of moderate-intensity dynamic exercise results in a sustained rise in skeletal muscle blood flow from that of pre-exercise levels. This postexercise skeletal muscle hyperemia is mediated by two histamine receptors (subtypes, H 1 and H 2 ). Skeletal muscle glucose uptake is also enhanced, in an insulin-independent manner, following moderate-intensity dynamic exercise. The impact of skeletal muscle hyperemia on glucose regulation following exercise has yet to be examined. Therefore, the purpose of this dissertation was to determine if postexercise skeletal muscle hyperemia plays a substantial role in glucose regulation in humans. In Chapter III I tested my ability to block local H 1 - and H 2 -receptors located in the vastus lateralis muscle in humans. The results demonstrate that I was able to successfully block the increase in local blood flow evoked by compound 48-80 with the combination of the H 1 -receptor antagonist pyrilamine and the H 2 -receptor antagonist cimetidine, administered via skeletal muscle microdialysis. In Chapter IV I sought to determine the effect of local combined H 1 - and H 2 -receptor blockade, administered via skeletal muscle microdialysis, on postexercise interstitial glucose concentrations. My findings indicate postexercise delivery of glucose to the interstitial space of the previously active skeletal muscle is mediated, in part, by local H 1 - and H 2 -receptors. In Chapter V I examined the effect of oral administration of H 1 - and H 2 -receptor antagonists on glucose regulation following a postexercise oral glucose load. The results showed that the glycemic and insulin responses to postexercise oral glucose load were more sustained with H 1 - and H 2 -receptor blockade versus control, suggesting a histaminergic effect on postexercise glucose regulation. / Adviser: John Halliwill

Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xiv, 197 p. : ill. Vita. Includes abstract. Includes bibliographical references.

Left coronary blood flow (LCBF), left ventricular oxygen, extraction [(a-v)O₂ ], and myocardial oxygen consumption (MVO₂) were monitored in 10 dogs. HR was paced at 120 bpm and then increased to 180 bpm to elicit a hyperemic response (ΔLCBF). During the hyperemia, the vaso-dilatory response to exogenous adenosine (F_AD) was tested. Twenty min. after injection of aminophylline (100 mg/i.v.), HR was again increased. F_AD was again tested. The pacing-induced increase in MVO₂ (ΔMVO₂) was not affected by aminophylline (P>0.05). However, the slope ΔLCBF/ΔMVO₂ was decreased, and the slope (a-v)O₂ /ΔMVO₂ was increased. F_AD was also decreased and the magnitude of the reduction was correlated with the decrease in ΔLCBF/ΔMVO₂ (r=0.82). These results suggest that adenosine may play an role in coronary functional hyperemia induced by increases in heart rate.

SAMMAMFATTNING Bakgrund: Reaktiv hyperemi definieras som ett övergående ökat blodflöde över det normala efter en tids ischemi. Det kan registreras med laserdopplerteknik. Att registrera reaktiv hyperemi är ett sätt att värdera mikrocirkulationen. Det finns många flödesvariabler att studera varav tid till maxflöde efter ocklusion är en. Det har gjorts studier som undersöker om det finns ett samband mellan reaktiv hyperemi och fysisk aktivitet/syreupptagningsförmåga. Det har inte gjorts någon studie som undersöker tid till maxflöde och fysisk aktivitet. Syftet var att undersöka om det finns ett samband mellan fysisk aktivitet och reaktiv hyperemi med avseende på tid till maxflöde. Material och metod: Testpersoner fick bära en accelerometer en vecka under dygnets alla vakna timmar samt göra en registrering av reaktiv hyperemi med laserdoppler. För statistiska beräkningar användes oparat T-test för att undersöka skillnad mellan olika grad av fysisk aktivitet och tid till maxflöde. Resultat: Ingen statistiskt signifikant skillnad mellan olika aktivitetsgrad och tid till maxflöde kunde observeras. Slutsats: Den här studien visade inte på statistiskt signifikant samband mellan blodflöde och fysisk aktivitet.

Thesis (Ph. D.)--University of Oregon, 2008. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 151-168). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

Le vieillissement est à l'origine de pathologies dermatologiques diverses favorisées par des facteurs extrinsèques, principalement les UV : cancers cutanés, dermatoporose, ulcères, escarres … Parmi eux, les ulcères sont source de douleurs chroniques, hospitalisations, majoration des coûts de santé et décès dans la population âgées. Or, le lien entre vieillissement cutané, vieillissement microvasculaire et ulcères n'est actuellement pas établi. Notre objectif est d'évaluer la dysfonction endothéliale liée au vieillissement sur les sites privilégiés d'ulcères, après développement des techniques d'évaluation de la fonction microvasculaire cutanée chez des sujets jeunes. La première partie de notre travail s'intéresse aux méthodes les plus récentes de mesure du flux sanguin cutané. Elle vise à comparer le Laser Speckle Contrast Imaging et le Laser Doppler Imaging en termes de reproductibilité puis à évaluer la corrélation des mesures selon ces deux techniques. La seconde partie est une étude méthodologique concernant la microdialyse, qui a pour objectif de comparer l'insertion des fibres au niveau intra-dermique ou sous-dermique, ainsi que d'évaluer leur pertinence dans la mesure de l'hyperhémie post-occlusive et par chauffage local. Dans la troisième partie, nous étudions le vieillissement physiologique de la fonction endothéliale de la zone périmalléolaire, zone à risque d'ulcération chez le sujet âgé. D'autres études seront nécessaires pour évaluer si la dysfonction microvasculaire liée au vieillissement peut favoriser la survenue d'ulcères et en préciser les mécanismes. / Aging is the cause of different dermatological diseases, facilitated by extrinsic factors, especially UV radiation: skin cancers, dermatoporosis, ulcers … Chronic ulcerations cause chronic pains, hospitalizations, increasing cost of health, death in the elderly population. Yet, the link between skin aging, microvascular aging and ulcers remains still unclear. Our objective is to study microvascular function on the gaiter skin area of elderly, because abnormal microvascular reactivity could contribute to ulcerations in this region, after development of the techniques used to assess cutaneous microvascular reactivity to young subjects. The first part of our work is interested in the most recent methods of measure of the cutaneous blood flow. It aims at comparing the Laser Speckle Contrast Imaging and the Laser Doppler Imaging in terms of reproducibility then at estimating the correlation of the measures according to these two techniques. The second part is a methodological study concerning the microdialysis, to determine wether intradermal or subdermal microdialysis fibers insertion can be used to assess post-occlusive hyperemia and local thermal hyperemia. In the third part, we study the physiological aging of in the supramedial malleolar skin, high-risk area of ulceration to the elderly subject. Further studies are required to determinate whether the changes in the physiological microvascular responses to local heating explain the higher incidence of skin ulcerations in the elderly.

The purpose of this study was to define a lower standard cuff occlusion time to induce reactive hyperemia in assessing endothelial dysfunction. In this study, strong evidence was found by a novel technique that used oscillometric methods, which supported that 3 minute reactive hyperemia was sufficient to elicit a significant difference in arterial compliance from baseline. Twenty healthy Cal Poly students were assessed, (n=12 female, n=8 male) aged 22 years old with a standard deviation of 2.04 years. Arterial compliance was estimated by measuring the peak-to-peak oscillations for baseline, 3 minute reactive hyperemia, and 5 minute reactive hyperemia tests, with the result being statistical evidence of an increase in arterial compliance after 3 minutes of cuff occlusion compared to baseline. The peak-to-peak mean for the 3 minute reactive hyperemia test was significantly greater than the baseline peak-to-peak mean with p-values less than 0.0001. These results support that 3 minute reactive hyperemia is sufficient to assess endothelial dysfunction using oscillometry techniques. Endothelial dysfunction is the most significant predictor of a major adverse cardiovascular event, so this test can be used as an early detection tool for cardiovascular disease and allow patients to find treatment before irreversible damage is done to the body. Implementing this test into routine doctor checkups has the potential to have a significant effect on cardiovascular disease, which is the leading cause of death globally. The currently accepted clinical benchmark performed in hospitals uses high-frequency ultrasound with a standard cuff occlusion time of 5 minutes. Although noninvasive, 5 minutes of cuff occlusion causes slight discomfort to the patient and is not desirable. This test was improved and shortened by using a system based on the oscillometric method of blood pressure measurement. By reducing the duration of the test from 5 minute reactive hyperemia to 3 minute reactive hyperemia, this will make the procedure practical for an increased number of patients, providing a noninvasive option to regularly check for early symptoms of cardiovascular disease.