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This study aims to learn about the effects of continuous positive airway pressure (CPAP) on people with autonomic failure and high blood pressure when lying down (supine hypertension) to determine if it can be used to treat their high blood pressure during the night. CPAP (a widely used treatment for sleep apnea) involves using a machine that blows air into a tube connected to a mask covering the nose, or nose and mouth, to apply a low air pressure in the airways. The study includes 3-5 days spent in the Vanderbilt Clinical Research Center (CRC): at least one day of screening tests, followed by up to 3 study days. Subjects may be able to participate in daytime and/or overnight studies. The Daytime study consists of 2 study days: one with active CPAP and one with sham CPAP applied for up to 2 hours. The Overnight study consists of 3 study nights: one with active CPAP, one with sham CPAP, both applied for up to 9 hours and one night sleeping with the bed tilted head-up.
The objective of this study is to find a more objective and accurate way to assess the efficacy of the treatment for neurogenic orthostatic hypotension. For this purpose, the investigators will use an activity monitor to determine the amount of time patients spend in the upright position (standing and walking; upright time) during 1 week of placebo (a pill with no active ingredients) and 1 week of their regular medication for orthostatic hypotension (midodrine or atomoxetine at their usual doses). Total upright time (i.e. tolerance to standing and walking) will be compared between placebo and active treatment to test the hypothesis that it can be used to assess the efficacy of the treatment for orthostatic hypotension and whether this outcome is superior to the assessment of symptoms using validated questionnaires.
The purpose of this study is to learn more about the effects of abdominal compression and the medication midodrine, two interventions used for the treatment of orthostatic hypotension (low blood pressure on standing), on hemodynamic markers of cardiovascular risk. The study will be conducted at the Vanderbilt University Medical Center and consists of a screening and 2 testing days, one with abdominal compression and one with midodrine. The total length of the study will be about 5 days.
Alpha-synucleinopathies refer to age-related neurodegenerative and dementing disorders, characterized by the accumulation of alpha-synuclein in neurons and/or glia. The anatomical location of alpha-synuclein inclusions (Lewy Bodies) and the pattern of progressive neuronal death (e.g. caudal to rostral brainstem) give rise to distinct neurological phenotypes, including Parkinson's disease (PD), Multiple System Atrophy (MSA), Dementia with Lewy Bodies (DLB). Common to these disorders are the involvement of the central and peripheral autonomic nervous system, where Pure Autonomic Failure (PAF) is thought (a) to be restricted to the peripheral autonomic system, and (b) a clinical risk factor for the development of a central synucleinopathy, and (c) an ideal model to assess biomarkers that predict phenoconversion to PD, MSA, or DLB. Such biomarkers would aid in clinical trial inclusion criteria to ensure assessments of disease- modifying strategies to, delay, or halt, the neurodegenerative process. One of these biomarkers may be related to the neurotransmitter dopamine (DA) and related changes in the substantia nigra (SN) and brainstem. \[18F\]F-DOPA is a radiolabeled substrate for aromatic amino acid decarboxylase (AAADC), an enzyme involved in the production of dopamine. Use of this radiolabeled substrate in positron emission tomography (PET) may provide insight to changes in monoamine production and how they relate to specific phenoconversions in PAF patients. Overall, this study aims to identify changes in dopamine production in key regions including the SN, locus coeruleus, and brainstem to distinguish between patients with PD, MSA, and DLB, which may provide vital information to predict conversion from peripheral to central nervous system disease.
The automated inflatable abdominal binder is an investigational device for the treatment of orthostatic hypotension (low blood pressure on standing) in patients with autonomic failure. The purpose of this study is to determine safety and effectiveness of the automated abdominal binder in improving orthostatic tolerance in these patients.
Patients with autonomic failure are characterized by disabling orthostatic hypotension (low blood pressure on standing), and at least half of them also have high blood pressure while lying down (supine hypertension). Exposure to heat, such as in hot environments, often worsens their orthostatic hypotension. The causes of this are not fully understood. The purpose of this study is to evaluate whether applying local heat over the abdomen of patients with autonomic failure and supine hypertension during the night would decrease their nocturnal high blood pressure while lying down. This will help us better understand the mechanisms underlying this phenomenon, and may be of use in the treatment of supine hypertension.
The purpose of this study is to learn more about the effects of midodrine and droxidopa, two medications used for the treatment of orthostatic hypotension (low blood pressure on standing), on the veins of the abdomen of patients with autonomic failure. The study will be conducted at Vanderbilt University Medical Center, and consists of 2 parts: a screening and 2 testing days. The total length of the study will be about 5 days. About 34 participants will be screened for the study.
Compression garments have been shown to be effective in the treatment of orthostatic hypotension in autonomic failure patients. The purpose of this study is to determine the hemodynamic mechanisms by which abdominal compression (up to 40 mm Hg) improve the standing blood pressure and orthostatic tolerance in these patients, and to compare them with those of the standard of care midodrine. The investigators will test the hypothesis that abdominal compression will blunt the exaggerated fall in stroke volume and the increase in abdominal vascular volume during head up tilt.
Synucleinopathies are a group of rare diseases associated with worsening neurological deficits and the abnormal accumulation of the protein α-synuclein in the nervous system. Onset is usually in late adulthood at age 50 or older. Usually, synucleinopathies present clinically with slowness of movement, coordination difficulties or mild cognitive impairment. Development of these features indicates that abnormal alpha-synuclein deposits have destroyed key areas of the brain involved in the control of movement or cognition. Patients with synucleinopathies and signs of CNS-deficits are frequently diagnosed with Parkinson disease (PD), dementia with Lewy bodies (DLB) or multiple system atrophy (MSA). However, accumulation of alpha-synuclein and death of nerve cells can also begin outside the brain in the autonomic nerves. In such cases, syncucleinopathies present first with symptoms of autonomic impairment (unexplained constipation, urinary difficulties, and sexual dysfunction). In rare cases, hypotension on standing (a disorder known as orthostatic hypotension) may be the only clinical finding. This "pre-motor" autonomic stage suggests that the disease process may not yet have spread to the brain. After a variable period of time, but usually within 5-years, most patients with abnormally low blood pressure on standing develop cognitive or motor abnormalities. This stepwise evolution indicates that the disease spreads from the body to the brain. Another indication of this spread is that acting out dreams (i.e., REM sleep behavior disorder, RBD) a problem that occurs when the lower part of the brain is affected, may also be the first noticeable sign of Parkinson disease. The purpose of this study is to document the clinical features and biological markers of patients with synucleinopathies and better understand how these disorders evolve over time. The study will involve following patients diagnosed with a synucleinopathy (PD/DLB and MSA) and those believed to be in the "pre-motor" stage (with isolated autonomic impairment and/or RBD). Through a careful series of follow-up visits to participating Centers, we will focus on finding biological clues that predict which patients will develop motor/cognitive problems and which ones have the resilience to keep the disease at bay preventing spread to the brain. We will also define the natural history of MSA - the most aggressive of the synucleinopathies.
Supine hypertension is a common problem that affects at least 50% of patients with primary autonomic failure. Supine hypertension can be severe and complicates the treatment of orthostatic hypotension. The purpose of this study is to assess whether continuous positive airway pressure (CPAP) decreases blood pressure in autonomic failure patients with supine hypertension.