Active clinical trials for "Orthostatic Intolerance"

Background: The investigational device, "Task Force® CORE" (TFC, CNSystems Medizintechnik GmbH, Graz, Austria) together with the "Task Force® CARDIO" (TFCARDIO, CNSystems Medizintechnik GmbH, Graz, Austria) medical device software, is a new CE-marked medical device for continuous non-invasive determination of blood pressure (BP), cardiac output (CO) and derived parameters based on the well established CNAP® (continuous non-invasive arterial pressure) technology by CNSystems. Aim: The primary aim of this prospective, method comparison, open study is data acquisition for the performance evaluation of the TFC during autonomic function testing in comparison with an clinically accepted reference method. Setting: The setting of the clinical investigation will be the autonomic function testing laboratory at the Department of Neurology, the University Hospital Center Zagreb. Inclusion criteria: Patients who are over 18 years and who provide written informed consent. Sample size: The study has an calculated sample size of 70 patients. Considering a drop-out rate of 5%, a total of 75 patients will be included. Statistics: Descriptive statistics, values for the percentage error and correlation estimates will be derived. Furthermore, scatterplot, Bland-Altman analysis, concordance analysis of parameter changes and further comparative statistics will be performed.

The purpose of the proposed research is to determine how changes in kidney dopamine (DA) activity influence urinary sodium excretion. We will decrease DA activity in the kidney by inhibiting DA synthesis via carbidopa administration. We want to compare findings in normal volunteers and in patients with postural tachycardia syndrome (POTS). We will test the null hypothesis (Ho) that the effects of oral carbidopa administration on urinary sodium excretion will not differ between patients with POTS and healthy volunteers.

The study evaluates the pathophysiological effects of a single dose Methylprednisolone administered prior to total hip-arthroplasty (THA) surgery. The investigators examine the effect on orthostatic intolerance, orthostatic hypotension and heart rate variability (HRV) to evaluate the efficacy of Methylprednisolone regarding blood pressure regulation and autonomic responses after THA. Half of participants will receive intravenous Solu-Medrol 125 mg, while the other half will receive placebo. The investigators hypothesize that the group receiving Methylprednisolone will be less orthostatic intolerant, experience less orthostatic hypotension and have an improved autonomic response compared to the placebo-group, early after THA.

The investigators propose to test the hypothesis that the sympathetic nervous system contributes to the cardiovascular and inflammatory abnormalities present in the chronic fatigue syndrome (CFS) and, in particular in the subset of patients characterized by postural tachycardia syndrome (POTS). CFS and POTS are seen mostly in otherwise normal young women, and are the cause of significant disability. A substantial proportion of patients referred for evaluation of POTS met diagnostic criteria for CFS and, conversely, a subset of patients referred for treatment for CFS have POTS. The investigators hypothesize that sympathetic activation underlies the pathophysiology of patients in whom CFS and POTS overlap (CFS-P).

Postural Orthostatic Tachycardia Syndrome (POTS) is characterized by symptoms of chronic orthostatic intolerance such as fatigue, lightheadedness, dizziness, palpitations and by pronounced tachycardia upon standing. The aims of the present research study are to test whether a daily transcutaneous vagal nerve stimulation (tVNS) performed for 14 consecutive days may improve heart rate response and reduce disabling symptoms while standing.

We and others have shown that many younger patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) have orthostatic intolerance (OI), i.e., they can't tolerate prolonged standing. OI in ME/CFS is often accompanied by either postural tachycardia syndrome (POTS) in which standing results in an excessive heart rate, and neurally mediated hypotension (NMH) in which standing causes a fall in blood pressure and fainting. Intravenous fluids can alleviate these symptoms, but is difficult to administer; oral fluids fail to provide the same benefit. We would therefore like to test the effectiveness of an oral rehydration solution (ORS, W.H.O. formula) making use of co-transport of glucose and sodium, to reverse these symptoms in ME/CFS subjects with POTS or NMS, and will compare these results with healthy control subjects.

This study will evaluate whether treatment with the α1-agonist, midodrine, reduces subjective orthostatic lightheadedness as measured by the Non-Motor Symptoms Scale for Parkinson's Disease (NMSS) questionnaire, in patients with (positive control group, OH) or without documented orthostatic hypotension(orthostatic intolerance, OI). It will also demonstrate the effect of treatment with an α1-agonist, midodrine, on beat-to-beat blood pressure and heart rate response during Valsalva maneuver (measured by Continuous Non-invasive Arterial Pressure, CNAP) in patients with OI or OH and evaluate the relationship to symptom improvement.

The investigators will test to determine if an external Automated Abdominal Binder (non-commercial product) during high sodium diet improves orthostatic tolerance, compared to wearing the binder during a low sodium diet session.

Postural tachycardia syndrome (POTS), is the chronic form of orthostatic intolerance associated with excessive upright tachycardia, and occurs predominantly in young females (>85%). Among its most troubling symptoms are lightheadedness, fatigue, and decreased memory often called "brain fog" by patients. Task-related neurovascular coupling (NVC) links neural activity to an increase in CBF known as "functional hyperemia". Although memory task performance and NVC deteriorated with angle of tilt in POTS but not healthy controls, cerebral blood flow (CBF) remained similar to control. Instead, the investigators observed extensive narrow band low frequency (0.07-0.13 Hz) oscillations in BP (OBP) that entrained and amplified oscillations in CBF (OCBF). OBP and OCBF increased with tilt angle and caused impaired working memory and reduced functional hyperemia. The cardiovagal baroreflex couples BP to HR to buffer BP changes. The investigators hypothesize that the cardiovagal baroreflex becomes progressively impaired with orthostasis in POTS, but not in healthy volunteers, and accounts for OBP, OCBF, and loss of NVC; further, improving the baroreflex reduces OBP, OCBF and Brain Fog in POTS.

The primary purpose of this study is to investigate the relationship between the extent of neurologic (nerve) impairment in patients with spinal cord injuries and how well the nerves passing down the spine to the heart and blood vessels are working. These nerves are called the descending spinal sympathetic pathway (DSSP) and are important in controlling many functions, including blood pressure. We also wish to examine how injury severity and DSSP function influence blood levels of nor-epinephrine and epinephrine. Nor-epinephrine and epinephrine are hormones released into the blood that are also important in controlling blood pressure. Thus, we will also look at how the effect of the extent of DSSP dysfunction influences heart rate and blood pressure and blood levels of certain enzymes.