View clinical trials related to Orthostatic Intolerance.
Filter by:In previous work the investigator identified a group of children between the ages of 10-18 years whose diagnostic workup for chronic nausea unexplained by conventional diagnostic tests has unexpectedly revealed underlying cardiovascular instability manifesting as orthostatic intolerance, primary defined as postural orthostatic tachycardia syndrome (POTS) (88%). While this is an atypical initial presentation for orthostatic intolerance in general, the investigator believes that the cardiovascular problem is serious and represents a cause of the nausea in a majority of these individuals, as treatment of the POTS with fludrocortisone reduced the symptoms of nausea. While fludrocortisone treatment abrogates the fall in baroreflex sensitivity (BRS) during tilt in part, it did not completely correct the tachycardia symptoms or the BRS suppression during HUT. Furthermore it caused an elevation in MAP in supine position, which may lead to future cardiovascular problems such as early onset hypertension and cardiac hypertrophy. This argues for a different treatment approach. The investigator presents preliminary data in this application revealing that OI subjects tend to have lower 25-hydroxy vitamin D (25(OH)D) compared to non OI subjects.
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.
The purpose of this study is to see if some people with postural tachycardia syndrome (POTS) have higher levels of immune proteins (autoantibodies) directed against receptors of the autonomic nervous system, and if these autoantibodies make a difference in their POTS symptoms. The investigators also want to see if the levels of these autoantibodies stay the same over time.
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.
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.
Orthostatic intolerance refers to symptoms that occur with standing and improve or resolve with recumbency. Few studies have evaluated orthostatic intolerance symptoms by electroencephalography (EEG), and none of those studies have focused on the adolescent-aged patient. This study will compare EEG characteristics and sweat rate during head-upright tilt (HUT) testing among patients with postural tachycardia syndrome (POTS) and patients with syncope without POTS. Patients with POTS will also undergo a separate HUT with abdominal and lower extremity compression. The primary aim of this study is to characterize video EEG changes that correspond with orthostatic intolerance in youth during HUT testing. The investigators hypothesize that the clinical encephalopathy related to POTS and referred to as 'brain fog' will have an electrographic correlate. Secondary aims include (1) EEG comparisons of POTS symptoms with and without abdominal and lower extremity compression during HUT, (2) correlation between sweat rate and EEG changes during HUT, and (3) analysis of EEG characteristics that distinguish syncope with POTS from syncope without POTS. The investigators hypothesize that POTS patients have prolonged syncopal prodromes (compared to syncope patients without POTS) which are protective of syncope during daily activities.
The purpose of this observational study is to evaluate the baroreceptor function in relation to surgical inflammation and orthostatic intolerance after elective hip arthroplasty. The main hypothesis is that baroreceptor function is attenuated after surgery and related to surgical inflammation.
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.
The aim of this study is to examine the efficacy of 5 mg Midodrine (Gutron) vs. placebo on reducing the incidence of orthostatic hypotension during mobilization 6 h after a total hip arthroplasty.
This project aims to evaluate the physiological effects of Midodrine administration during orthostatic challenge in those with high level spinal cord injury. Midodrine has been shown to improve orthostatic symptoms in those with spinal cord injury but the physiological mechanisms influenced have not been identified. The investigators will examine key physiological components influencing orthostatic tolerance. The investigators will do this, by measuring the baroreflex, and brain blood flow autoregulation (the ability to maintain brain blood flow) before during and after the sit-up test. Two sit-up tests will occur; one before Midodrine administration, and one after administration of a 10mg dose of Midodrine.