View clinical trials related to Orthostatic Intolerance.
Filter by:Pilot-case-control study on exertion and orthostatic intolerance of adolescents with myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS) compared to age-matched healthy controls (HC).
Rationale: Systolic hypertension represents the leading risk for burden of disease among older adults (age >70 years), with an increasing prevalence due to the increase in lifespan. Antihypertensive drug treatment (AHT) is beneficial in fit (non-frail) older adults, with substantial (≈40 %) risk reductions for cardiovascular events and mortality. Scarce evidence exists on the risks of adverse effects related to AHT. It has been suggested in medical literature that AHT in frail elderly might cause cerebral hypoperfusion and/or orthostatic hypotension. Therefore, current guidelines advise clinicians to be more cautious regarding treatment targets in this population. However, the evidence for these adverse effects is limited to observational and cross-sectional data and opinion pieces. In contrast to the suggestion of potential adverse effects of AHT in elderly, recent experimental data and secondary analyses of clinical trials do not provide support for this statement. However, evidence in frail older patients remains scarce. Studies that directly examine the safety of AHT with regard to cerebral hemodynamics and orthostatic tolerance in frail elderly are needed to inform potential changes in current treatment guidelines and prevent undertreatment of hypertension in frail older patients. Objective: To examine the impact of medication induced systolic BP (SBP) reductions ≥10 mmHg, while reaching a treatment target of ≤140 mmHg, on cerebral blood flow (CBF) in frail elderly with untreated or uncontrolled systolic hypertension at baseline. We hypothesise that these blood pressure lowering targets (which are consistent with clinical guidelines for non-frail older patients) are not accompanied by detrimental reductions in CBF (i.e. >10% from baseline). Study design: An explorative observational study will be performed to examine the effects of medication induced SBP reductions ≥10 mmHg to office SBP ≤140 mmHg on CBF in frail elderly with untreated or uncontrolled hypertension. Participants will be treated as in usual patient care for older adults with hypertension. Participants will undergo one baseline assessment before exposure to (additional) AHT, followed by in duplo follow-up assessments 6-10 weeks after the start of AHT. The in duplo follow-up evaluations will be performed on separate days within 2 weeks while continuing treatment. Study population: Twelve frail (Clinical Frailty Scale 4-7) elderly (age ≥70 years) with untreated or uncontrolled systolic hypertension (office SBP ≥150 mmHg) that will be subjected to (additional) AHT as part of regular care. Main study parameters/endpoints: The change in resting CBF from baseline to follow-up (i.e. the average of the in duplo follow-up assessments). Secondary outcomes relate to cerebrovascular autoregulation (CA) and orthostatic tolerance. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Subjects will be subjected to AHT, essentially identical to what is considered 'guideline care', while their wellbeing will be monitored closely. Since all study procedures and used measurement techniques are non-invasive, the nature and extent of burden and risks associated with participation and measurements are negligible.
More than 78 million adults in the U.S. are obese. Bariatric surgery is the only modality that results in sustained weight loss along with reversal of diabetes mellitus, and a decrease in cardiovascular events. Obesity is associated with increased sympathetic nervous system (SNS) activity that contributes to blood pressure regulation; sympathetic vasoconstrictor activity is maximally activated upon standing and is fundamental for the maintenance of orthostatic tolerance. After bariatric surgery, there is a significant and sustained reduction in SNS activity at three and six months after the procedure, which is related to weight loss. Recently, multiple retrospective studies have reported an orthostatic intolerance (OI) syndrome after bariatric surgery characterized by chronic pre-syncopal symptoms, syncope and orthostatic hypotension. In the Vanderbilt University Medical Center bariatric surgical center, 741 post-bariatric surgery patients reported OI symptoms, 98 (13.2%) of these patients, progressed to chronic OI and in17 cases, the OI was so disabling that patients initiated treatment with pressor agents. More than 50% of OI cases in the cohort developed the condition during a weight-stable period. Hence, investigators propose the novel hypothesis that after bariatric surgery, the persistent reduction in SNS activity contributes to impaired orthostatic tolerance, which is independent of weight loss.
Incidence of Postoperative Orthostatic Intolerance and Postoperative Orthostatic Hypotension in Patients Undergoing Unilateral Total Knee Arthroplasty
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.
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.
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.
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 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.