Orthostatic IntoleranceIOHNCT03970551
Lower Body Muscle Pre-activation in Initial Orthostatic Hypotension
A study testing Physical Counter-maneuver, Stress Test and Functional Electrical Stimulation in people with Orthostatic Intolerance and Syncope, run by University of Calgary at 1 site in Canada.
Trial summary
This study is aimed primarily at providing a simple and effective form of treatment to reduce the symptoms of Initial Orthostatic Hypotension (IOH) and prevent syncope. We will first characterize the physiology of IOH, and then we will study four sit-to-stand maneuvers, each with a different stress tests to identify… Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Orthostatic Intolerance, Syncope, Fainting
- What is being tested?
- Physical Counter-maneuver, Stress Test and Functional Electrical Stimulation
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 64 participants
- Where
- 1 siteCanada
- Study dates
- 1 Jul 2019to 31 Dec 2023
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Either have initial orthostatic hypotension or are a healthy volunteer
- 18-50 years old
- Male or Female
- Ability to travel to Libin Cardiovascular Institute of Alberta Autonomic Research Testing Lab in the Teaching, Research \& Wellness Building at the University of Calgary, Calgary, AB
- Able and willing to provide informed consent
Who cannot join
- Inability to stand up or perform leg exercises without assistance
- Sustained orthostatic hypotension past 3 minutes of standing
- Pregnant
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Lower Body Muscle Pre-activation in Initial Orthostatic Hypotension: Effects on Orthostatic Tolerance
This study is aimed primarily at providing a simple and effective form of treatment to reduce the symptoms of Initial Orthostatic Hypotension (IOH) and prevent syncope. We will first characterize the physiology of IOH, and then we will study four sit-to-stand maneuvers, each with a different stress tests to identify the role of sympathetic activity vs. simple muscle contraction in IOH. Then we will complete an additional two sit-to-stands with interventions designed to decrease the blood pressure drop (and hopefully symptoms) with initial stand. These consist of physical counter maneuvers, which may be a possible treatment that can be used to mitigate the drop in blood pressure (BP) seen in IOH during a stand and relieve presyncope symptoms.
Read the detailed description
IOH is a form of orthostatic intolerance defined by a transient decrease in systolic blood pressure (SBP) by 40mmHg or diastolic blood pressure (DBP) by 20mmHg within the first 15-30 seconds of assuming a standing position from a supine or seated position. IOH commonly occurs in teenagers and young adults and is associated with presyncope symptoms such as nausea, light-headedness, and blurred vision and may sometimes lead to full syncope. These symptoms are a consequence of cerebral hypoperfusion caused by a rapid reduction in BP and are often present only during an active stand, and not with a passive tilt-table test. This suggests that a muscle activation reflex may play an important role underlying IOH. Identifying the refractory period of leg muscle activation will allow future investigators to accurately determine a common baseline seated period to allow hemodynamic recovery in patients after a stand. This will allow investigators to observe the physiological effects of repeated stands without any interference from a prior stand.
Upon standing there is a large shift of blood (approximately 500 mL) towards the lower extremities and abdomen. With this shift there is a decrease in venous return which results in a drop in BP. Subsequently, the decrease in BP activates the baroreceptors to increase sympathetic activity and reduce parasympathetic activity, which functions to restore BP by increasing heart rate (HR) and total peripheral resistance (TPR).
The underlying physiological mechanism behind the large decrease in blood pressure upon standing in IOH patients has not yet been confirmed. The most widely accepted explanation at this time involves rapid vasodilation localized to the contracting leg muscles during a stand. Research in both human and animal models from the past couple of decades have shown that skeletal muscle resistance vessels can dilate rapidly in response to, as well as in proportion to, a singular brief muscle contraction. This effect may be exaggerated in IOH patients, which could explain the decrease in TPR in IOH patients upon a stand and thus their subsequent drop in blood pressure. Current treatments of IOH include non-pharmacological interventions and physical counter-maneuvers such as standing up slowly or sitting up first before fully standing.
Physical counter-measures function to oppose the gravitational pull experienced on systemic circulation during a stand. During a stand, a large percentage of circulating blood shifts towards the lower extremities and abdomen resulting in blood pooling. Gravitational venous pooling can be minimized and opposed by performing a physical countermeasure such as a lower-body muscle contraction to translocate blood centrally. Sustained tensing of the lower-body muscles prevents further peripheral pooling in the legs and abdomen.
The investigators hypothesize that pre-activation of lower body muscles prior to standing, will attenuate the drop in SBP seen in IOH patients upon a stand, and alleviate symptoms of IOH, compared to an active stand without muscle pre-activation. The study participant will complete 14 active stands in total within a single day. The first 8 stands will be in an attempt to define the refractoriness of leg muscle activation. The next 4 stands will involve stress tests prior to standing to isolate the roles of sympathetic activity vs. simple muscle contraction. The final 2 stands will involve physical counter-maneuvers intended to mitigate the large drop in BP seen in IOH patients upon a stand.
The first 8 stands will be performed from a seated position. They will begin at a 20 minute seated baseline before the first stand, then in a random order perform stands after baseline durations of 30 sec, 2 min, 3 min, 4 min, 5 min, 7 min, and 10 min.
The next 4 stands will also be performed from a seated position. The interventions that will be performed in a random order are: (1) free stand with no intervention, (2) Serial 7's mental arithmetic stress test, (3) Cold Pressor stress test, (4) functional electrical stimulation.
The final 2 stands will be performed from a seated position as well. The interventions that will be performed in a random order are: (1) supine knee raises and tensing prior to standing and (2) leg crossing and tensing after standing. The entire study will take approximately 3-4 hours.
The study participant will be instrumented in a fasting state and on an empty bladder. The investigators will apply skin electrodes to continuously monitor heart rate and record an ECG. BP will be monitored continuously using finger volume clamp photoplethysmography and calibrated with intermittent brachial cuff measurements. From the continuous BP waveform, the investigators can obtain an estimate of stroke volume, cardiac output, and systemic vascular resistance (Modelflow). Oxygen saturation will be assessed from a finger probe. Middle cerebral blood flow velocity will be assessed using transcranial doppler (TCD).
- Conditions
- Orthostatic Intolerance, Syncope, Fainting, Presyncope
- Being tested
- Physical Counter-maneuver, Stress Test, Functional Electrical Stimulation
- Keywords
- Initial Orthostatic Hypotension, IOH, Physical Counter-maneuver, Refractory Period, Active Stand, Muscle Tensing, Leg Crossing, Lower Body Muscle Tensing
- Medical subject headings
- Orthostatic Intolerance, Syncope
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Physical Counter-maneuverOther
Physical counter-maneuver targeted at minimizing the large drop in BP seen in IOH patients.
Stress TestOther
Also called Cold Pressor Test, Serial 7's Stress Test
Stress test involving submerging your hand in ice water or performing mental arithmetic to increase sympathetic activity.
Functional Electrical StimulationOther
A mild electrical stimulus to passively induce a leg muscle contraction with minimal sympathetic activation.
| Study group | Role | What they receive |
|---|---|---|
| No Physical Intervention | No intervention | The participant will actively stand up from a seated position without performing any physical counter-maneuvers either prior to or following the stand. |
| Supine Knee Raises | Experimental | The participant will perform 30 seconds of raising their knees to their chest while sitting down before actively standing. Receives: Other: Physical Counter-maneuver |
| Leg Crossing | Experimental | The participant will actively stand and then immediately cross their legs and tense their leg muscles for 60 seconds. Receives: Other: Physical Counter-maneuver |
| Cold Pressor Test | Experimental | The participant will submerge their hands in ice water for approximately 45 seconds. Receives: Other: Stress Test |
| Serial 7's Stress Test | Experimental | The participant will perform a mental arithmetic stress test for 30 seconds prior to standing. Receives: Other: Stress Test |
| Functional Electrical Stimulation | Experimental | The participant will have their quadriceps passively contracted using mild electrical stimulation for approximately 30 seconds prior to standing. Receives: Other: Functional Electrical Stimulation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Magnitude of change in SBP from sitting to stand with a physical intervention
The magnitude of change in SBP from sitting to stand when the participant performs muscle pre-activation before a stand compared to no intervention at all.
Measured: < 5 minutes
Secondary outcomes (4)
Differences in Vanderbilt Orthostatic Symptoms Score (VOSS) Symptom Rating
Subjective symptom scoring as reported by participant during each study arm. The VOSS evaluates 9 symptoms on a 0 to 10 scale with 0 being no symptom to 10 being worst ever symptom. The total score ranges from 0-90, with a higher score being more severe symptoms.
The 9 symptoms are mental clouding, blurred vision, shortness of breath, rapid heartbeat, tremulousness, chest discomfort, headache, lightheadedness, and nausea. The participant's VOSS score will be compared across the 4 arms of this study.
The VOSS score has been previously used in multiple publications
Measured: < 5 minutes
Nadir SBP
Nadir systolic blood pressure when standing during each study arm.
Measured: < 5 minutes
Peak HR
Peak heart rate when standing during each study arm.
Measured: < 5 minutes
Cerebral Blood Flow Velocity (CBFV)
CBFV when standing during each study arm.
Measured: < 5 minutes
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted31 May 2019
- Study start1 Jul 2019
- Primary completion31 Dec 2023 (estimated)
- Study completion31 Dec 2023 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (11)Papers the sponsor has linked to this study.
- Other trials for Orthostatic IntoleranceStudies of the same condition, open and under way.
- More trials run by University of CalgaryThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- There will be 6 stands that will involve standing from a sitting position and performing physical counter-maneuvers or a stress test either prior to or following the stand. The order of the interventions will be randomized. Both healthy participants and IOH patients will perform all stands.
- Masking
- None (open label)
- Enrolment
- 64 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Calgary
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Satish R Raj, MD, MSCI, Principal investigator, University of Calgary
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03970551
- Sponsor's protocol ID
- REB19-0792
- Acronym
- IOH
- Status last verified
- Apr 2021
- First submitted
- 24 May 2019
- Last updated
- 29 Apr 2021
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: I will not be sharing individual participant data.
Publications
da Silva RM. Syncope: epidemiology, etiology, and prognosis. Front Physiol. 2014 Dec 8;5:471. doi: 10.3389/fphys.2014.00471. eCollection 2014.
PubMed 25538626McJunkin B, Rose B, Amin O, Shah N, Sharma S, Modi S, Kemper S, Yousaf M. Detecting initial orthostatic hypotension: a novel approach. J Am Soc Hypertens. 2015 May;9(5):365-9. doi: 10.1016/j.jash.2015.02.006. Epub 2015 Feb 13.
PubMed 25816712Eser I, Khorshid L, Gunes UY, Demir Y. The effect of different body positions on blood pressure. J Clin Nurs. 2007 Jan;16(1):137-40. doi: 10.1111/j.1365-2702.2005.01494.x.
PubMed 17181675Wieling W, Krediet CT, van Dijk N, Linzer M, Tschakovsky ME. Initial orthostatic hypotension: review of a forgotten condition. Clin Sci (Lond). 2007 Feb;112(3):157-65. doi: 10.1042/CS20060091.
PubMed 17199559Stewart JM, Clarke D. "He's dizzy when he stands up": an introduction to initial orthostatic hypotension. J Pediatr. 2011 Mar;158(3):499-504. doi: 10.1016/j.jpeds.2010.09.004. No abstract available.
PubMed 20970148Stewart JM. Mechanisms of sympathetic regulation in orthostatic intolerance. J Appl Physiol (1985). 2012 Nov;113(10):1659-68. doi: 10.1152/japplphysiol.00266.2012. Epub 2012 Jun 7.
PubMed 22678960Tschakovsky ME, Matusiak K, Vipond C, McVicar L. Lower limb-localized vascular phenomena explain initial orthostatic hypotension upon standing from squat. Am J Physiol Heart Circ Physiol. 2011 Nov;301(5):H2102-12. doi: 10.1152/ajpheart.00571.2011. Epub 2011 Aug 19.
PubMed 21856921Wieling W, van Dijk N, Thijs RD, de Lange FJ, Krediet CT, Halliwill JR. Physical countermeasures to increase orthostatic tolerance. J Intern Med. 2015 Jan;277(1):69-82. doi: 10.1111/joim.12249. Epub 2014 May 5. No abstract available.
PubMed 24697914Krediet CT, Go-Schon IK, Kim YS, Linzer M, Van Lieshout JJ, Wieling W. Management of initial orthostatic hypotension: lower body muscle tensing attenuates the transient arterial blood pressure decrease upon standing from squatting. Clin Sci (Lond). 2007 Nov;113(10):401-7. doi: 10.1042/CS20070064.
PubMed 17561808van Twist DJL, Dinh T, Bouwmans EME, Kroon AA. Initial orthostatic hypotension among patients with unexplained syncope: An overlooked diagnosis? Int J Cardiol. 2018 Nov 15;271:269-273. doi: 10.1016/j.ijcard.2018.05.043.
PubMed 30223355Sheikh NA, Phillips AA, Ranada S, Lloyd M, Kogut K, Bourne KM, Jorge JG, Lei LY, Sheldon RS, Exner DV, Runte M, Raj SR. Mitigating Initial Orthostatic Hypotension: Mechanistic Roles of Muscle Contraction Versus Sympathetic Activation. Hypertension. 2022 Mar;79(3):638-647. doi: 10.1161/HYPERTENSIONAHA.121.18580. Epub 2022 Jan 6.
PubMed 34990207
Study at a glance
From the registry record, last updated by the sponsor on 29 Apr 2021. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Lower Body Muscle Pre-activation in Initial Orthostatic Hypotension: Effects on Orthostatic Tolerance
- ClinicalTrials.gov ID
- NCT03970551
- Acronym / sponsor ID
- IOH / REB19-0792
- Conditions
- Orthostatic Intolerance, Syncope, Fainting, Presyncope
- Keywords
- Initial Orthostatic Hypotension, IOH, Physical Counter-maneuver, Refractory Period, Active Stand, Muscle Tensing, Leg Crossing, Lower Body Muscle Tensing
- Study type
- Interventional
- Recruitment status
- Unknown status
- Enrolment
- 64 participants (estimated)
- Lead sponsor
- University of CalgaryUniversity, hospital or other
- Study start
- 1 Jul 2019 (actual)
- Primary completion
- 31 Dec 2023 (estimated)
- Study completion
- 31 Dec 2023 (estimated)
- First posted
- 31 May 2019 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study is aimed primarily at providing a simple and effective form of treatment to reduce the symptoms of Initial Orthostatic Hypotension (IOH) and prevent syncope. We will first characterize the physiology of IOH, and then we will study four sit-to-stand maneuvers, each with a different stress tests to identify the role of sympathetic activity vs. simple muscle contraction in IOH. Then we will complete an additional two sit-to-stands with interventions designed to decrease the blood pressure drop (and hopefully symptoms) with initial stand. These consist of physical counter maneuvers, which may be a possible treatment that can be used to mitigate the drop in blood pressure (BP) seen in IOH during a stand and relieve presyncope symptoms.
Detailed description
IOH is a form of orthostatic intolerance defined by a transient decrease in systolic blood pressure (SBP) by 40mmHg or diastolic blood pressure (DBP) by 20mmHg within the first 15-30 seconds of assuming a standing position from a supine or seated position. IOH commonly occurs in teenagers and young adults and is associated with presyncope symptoms such as nausea, light-headedness, and blurred vision and may sometimes lead to full syncope. These symptoms are a consequence of cerebral hypoperfusion caused by a rapid reduction in BP and are often present only during an active stand, and not with a passive tilt-table test. This suggests that a muscle activation reflex may play an important role underlying IOH. Identifying the refractory period of leg muscle activation will allow future investigators to accurately determine a common baseline seated period to allow hemodynamic recovery in patients after a stand. This will allow investigators to observe the physiological effects of repeated stands without any interference from a prior stand.
Upon standing there is a large shift of blood (approximately 500 mL) towards the lower extremities and abdomen. With this shift there is a decrease in venous return which results in a drop in BP. Subsequently, the decrease in BP activates the baroreceptors to increase sympathetic activity and reduce parasympathetic activity, which functions to restore BP by increasing heart rate (HR) and total peripheral resistance (TPR).
The underlying physiological mechanism behind the large decrease in blood pressure upon standing in IOH patients has not yet been confirmed. The most widely accepted explanation at this time involves rapid vasodilation localized to the contracting leg muscles during a stand. Research in both human and animal models from the past couple of decades have shown that skeletal muscle resistance vessels can dilate rapidly in response to, as well as in proportion to, a singular brief muscle contraction. This effect may be exaggerated in IOH patients, which could explain the decrease in TPR in IOH patients upon a stand and thus their subsequent drop in blood pressure. Current treatments of IOH include non-pharmacological interventions and physical counter-maneuvers such as standing up slowly or sitting up first before fully standing.
Physical counter-measures function to oppose the gravitational pull experienced on systemic circulation during a stand. During a stand, a large percentage of circulating blood shifts towards the lower extremities and abdomen resulting in blood pooling. Gravitational venous pooling can be minimized and opposed by performing a physical countermeasure such as a lower-body muscle contraction to translocate blood centrally. Sustained tensing of the lower-body muscles prevents further peripheral pooling in the legs and abdomen.
The investigators hypothesize that pre-activation of lower body muscles prior to standing, will attenuate the drop in SBP seen in IOH patients upon a stand, and alleviate symptoms of IOH, compared to an active stand without muscle pre-activation. The study participant will complete 14 active stands in total within a single day. The first 8 stands will be in an attempt to define the refractoriness of leg muscle activation. The next 4 stands will involve stress tests prior to standing to isolate the roles of sympathetic activity vs. simple muscle contraction. The final 2 stands will involve physical counter-maneuvers intended to mitigate the large drop in BP seen in IOH patients upon a stand.
The first 8 stands will be performed from a seated position. They will begin at a 20 minute seated baseline before the first stand, then in a random order perform stands after baseline durations of 30 sec, 2 min, 3 min, 4 min, 5 min, 7 min, and 10 min.
The next 4 stands will also be performed from a seated position. The interventions that will be performed in a random order are: (1) free stand with no intervention, (2) Serial 7's mental arithmetic stress test, (3) Cold Pressor stress test, (4) functional electrical stimulation.
The final 2 stands will be performed from a seated position as well. The interventions that will be performed in a random order are: (1) supine knee raises and tensing prior to standing and (2) leg crossing and tensing after standing. The entire study will take approximately 3-4 hours.
The study participant will be instrumented in a fasting state and on an empty bladder. The investigators will apply skin electrodes to continuously monitor heart rate and record an ECG. BP will be monitored continuously using finger volume clamp photoplethysmography and calibrated with intermittent brachial cuff measurements. From the continuous BP waveform, the investigators can obtain an estimate of stroke volume, cardiac output, and systemic vascular resistance (Modelflow). Oxygen saturation will be assessed from a finger probe. Middle cerebral blood flow velocity will be assessed using transcranial doppler (TCD).
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 6
- Model description
- There will be 6 stands that will involve standing from a sitting position and performing physical counter-maneuvers or a stress test either prior to or following the stand. The order of the interventions will be randomized. Both healthy participants and IOH patients will perform all stands.
| Arm | Type | Receives |
|---|---|---|
| No Physical Intervention | No intervention | –The participant will actively stand up from a seated position without performing any physical counter-maneuvers either prior to or following the stand. |
| Supine Knee Raises | Experimental | Other: Physical Counter-maneuverThe participant will perform 30 seconds of raising their knees to their chest while sitting down before actively standing. |
| Leg Crossing | Experimental | Other: Physical Counter-maneuverThe participant will actively stand and then immediately cross their legs and tense their leg muscles for 60 seconds. |
| Cold Pressor Test | Experimental | Other: Stress TestThe participant will submerge their hands in ice water for approximately 45 seconds. |
| Serial 7's Stress Test | Experimental | Other: Stress TestThe participant will perform a mental arithmetic stress test for 30 seconds prior to standing. |
| Functional Electrical Stimulation | Experimental | Other: Functional Electrical StimulationThe participant will have their quadriceps passively contracted using mild electrical stimulation for approximately 30 seconds prior to standing. |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Either have initial orthostatic hypotension or are a healthy volunteer
- 18-50 years old
- Male or Female
- Ability to travel to Libin Cardiovascular Institute of Alberta Autonomic Research Testing Lab in the Teaching, Research \& Wellness Building at the University of Calgary, Calgary, AB
- Able and willing to provide informed consent
Key exclusion criteria (3 listed)
- Inability to stand up or perform leg exercises without assistance
- Sustained orthostatic hypotension past 3 minutes of standing
- Pregnant
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Physical Counter-maneuverPhysical counter-maneuver targeted at minimizing the large drop in BP seen in IOH patients. | Other | Leg Crossing, Supine Knee Raises |
| Stress TestAlso: Cold Pressor Test, Serial 7's Stress TestStress test involving submerging your hand in ice water or performing mental arithmetic to increase sympathetic activity. | Other | Cold Pressor Test, Serial 7's Stress Test |
| Functional Electrical StimulationA mild electrical stimulus to passively induce a leg muscle contraction with minimal sympathetic activation. | Other | Functional Electrical Stimulation |
Primary outcome
Magnitude of change in SBP from sitting to stand with a physical intervention
Time frame: < 5 minutes
The magnitude of change in SBP from sitting to stand when the participant performs muscle pre-activation before a stand compared to no intervention at all.
4 secondary outcomes
Differences in Vanderbilt Orthostatic Symptoms Score (VOSS) Symptom Rating
Time frame: < 5 minutes
Nadir SBP
Time frame: < 5 minutes
Peak HR
Time frame: < 5 minutes
Cerebral Blood Flow Velocity (CBFV)
Time frame: < 5 minutes
Results and safety
Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 Apr 2021.
- Background: PubMed 25538626da Silva RM. Syncope: epidemiology, etiology, and prognosis. Front Physiol. 2014 Dec 8;5:471. doi: 10.3389/fphys.2014.00471. eCollection 2014.
- Background: PubMed 25816712McJunkin B, Rose B, Amin O, Shah N, Sharma S, Modi S, Kemper S, Yousaf M. Detecting initial orthostatic hypotension: a novel approach. J Am Soc Hypertens. 2015 May;9(5):365-9. doi: 10.1016/j.jash.2015.02.006. Epub 2015 Feb 13.
- Background: PubMed 17181675Eser I, Khorshid L, Gunes UY, Demir Y. The effect of different body positions on blood pressure. J Clin Nurs. 2007 Jan;16(1):137-40. doi: 10.1111/j.1365-2702.2005.01494.x.
- Background: PubMed 17199559Wieling W, Krediet CT, van Dijk N, Linzer M, Tschakovsky ME. Initial orthostatic hypotension: review of a forgotten condition. Clin Sci (Lond). 2007 Feb;112(3):157-65. doi: 10.1042/CS20060091.
- Background: PubMed 20970148Stewart JM, Clarke D. "He's dizzy when he stands up": an introduction to initial orthostatic hypotension. J Pediatr. 2011 Mar;158(3):499-504. doi: 10.1016/j.jpeds.2010.09.004. No abstract available.
- Background: PubMed 22678960Stewart JM. Mechanisms of sympathetic regulation in orthostatic intolerance. J Appl Physiol (1985). 2012 Nov;113(10):1659-68. doi: 10.1152/japplphysiol.00266.2012. Epub 2012 Jun 7.
- Background: PubMed 21856921Tschakovsky ME, Matusiak K, Vipond C, McVicar L. Lower limb-localized vascular phenomena explain initial orthostatic hypotension upon standing from squat. Am J Physiol Heart Circ Physiol. 2011 Nov;301(5):H2102-12. doi: 10.1152/ajpheart.00571.2011. Epub 2011 Aug 19.
- Background: PubMed 24697914Wieling W, van Dijk N, Thijs RD, de Lange FJ, Krediet CT, Halliwill JR. Physical countermeasures to increase orthostatic tolerance. J Intern Med. 2015 Jan;277(1):69-82. doi: 10.1111/joim.12249. Epub 2014 May 5. No abstract available.
- Background: PubMed 17561808Krediet CT, Go-Schon IK, Kim YS, Linzer M, Van Lieshout JJ, Wieling W. Management of initial orthostatic hypotension: lower body muscle tensing attenuates the transient arterial blood pressure decrease upon standing from squatting. Clin Sci (Lond). 2007 Nov;113(10):401-7. doi: 10.1042/CS20070064.
- Background: PubMed 30223355van Twist DJL, Dinh T, Bouwmans EME, Kroon AA. Initial orthostatic hypotension among patients with unexplained syncope: An overlooked diagnosis? Int J Cardiol. 2018 Nov 15;271:269-273. doi: 10.1016/j.ijcard.2018.05.043.
- Derived from this study: PubMed 34990207Sheikh NA, Phillips AA, Ranada S, Lloyd M, Kogut K, Bourne KM, Jorge JG, Lei LY, Sheldon RS, Exner DV, Runte M, Raj SR. Mitigating Initial Orthostatic Hypotension: Mechanistic Roles of Muscle Contraction Versus Sympathetic Activation. Hypertension. 2022 Mar;79(3):638-647. doi: 10.1161/HYPERTENSIONAHA.121.18580. Epub 2022 Jan 6.
- Individual participant dataSharing planned: No. I will not be sharing individual participant data.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Satish R Raj, MD, MSCI principal investigator
University of Calgary
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Physical Counter-maneuver, Stress Test and Functional Electrical Stimulation in people with Orthostatic Intolerance and Syncope, run by University of Calgary at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: status not confirmed, as of the sponsor's last update on 29 Apr 2021. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Magnitude of change in SBP from sitting to stand with a physical intervention (time frame: < 5 minutes). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT03970551, which also lists 11 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 Apr 2021.