Recruiting

Pediatric Syncope

Sponsor:

Simon Fraser University

Code:

NCT05633693

Conditions

Syncope, Vasovagal

Postural Orthostatic Tachycardia Syndrome

Orthostatic Intolerance

Eligibility Criteria

Sex: All

Age: 6 - 18

Healthy Volunteers: Not accepted

Interventions

Counterpressure Maneuvers

Baseline Stand

Study Details

Brief summary:

The investigators are interested in whether discrete counterpressure maneuvers, or muscle movements in the lower body, will boost blood pressure and cardiovascular control in children who faint. We will record cardiovascular responses to maneuvers of exaggerated sway, leg crossing, crouching, and gluteal muscle tensing in children who faint (N=20), as well as their height, weight, muscularity, and pubertal (Tanner) stage. Autonomic cardiovascular control will be measured using a Valsalva manoeuvre (expiration against a closed airway for 20 seconds) and a supine-stand test. The primary outcomes are noninvasive measures of cardiovascular responses to the maneuvers (blood pressure, cerebral blood flow, and stroke volume (volume of blood pumped per heartbeat). Comparisons will be made across levels of sex, diagnosis, Tanner stage, muscularity, height, and degree of autonomic control.

Conditions

Syncope, Vasovagal

Postural Orthostatic Tachycardia Syndrome

Orthostatic Intolerance

Study ID

NCT05633693

Start date

Apr 17, 2023

Status verified date

Apr, 2026

Completion date

Jun, 2027

Anticipated

Primary completion date

May, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 6 - 18

Healthy Volunteers: Not accepted

Inclusion Criteria:

We are looking for English speaking pediatric patients aged 6-18 years with a diagnosis of recurrent fainting (at least two episodes of fainting with loss of consciousness or near loss of consciousness in the last year) of a vasovagal origin or associated with the postural orthostatic tachycardia syndrome (POTS) (as determined by a paediatric cardiologist) to take part in this study.

Exclusion Criteria:

Those with a diagnosis of recurrent fainting accompanied by any of the following will not be eligible to take part:

Known history of:

  • Suspected or confirmed cardiac arrhythmia (e.g., Wolff-Parkinson-White, Long QT)
  • Traumatic head injury
  • New presentation of a seizure disorder OR epilepsy recurrence
  • Overdose or intoxication
  • Structural heart disease
  • Cardiovascular disease including hypertension, diabetes, or renal disease
  • Hypoglycemia
  • Physical and/or psychological disability that impact their ability to complete the tests

Female participants of childbearing age will be excluded if they are pregnant, or think they might be. Participants who are taking any cardiovascular acting medications, including treatment for cardiovascular disease, or medications for orthostatic syncope (e.g. fludrocortisone, slow-release sodium chloride, β-blockers, midodrine) will be excluded from the study.

In order to reduce the likelihood of transmission of COVID-19, participants will only be eligible to participate in the study if they have received full immunisation against COVID-19 according to current Health Canada guidelines. Accordingly, participants will be asked to provide evidence of their vaccination status in order to take part in the study.

Study Design

Enrollment

30 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Counterpressure Maneuvers

Counterpressure maneuver (CPM) trials will be performed in front of a neutral wall in silence to ensure that visual or auditory stimuli do not affect movement.

CPM:

  • Leg crossing and muscle tensing: Legs are crossed while upright and lower body musculature is isometrically contracted (clinical)
  • Crouching: Participant crouches down resting weight on the balls of their feet, pressing calves against the back surface of the thighs (clinical)
  • Exaggerated anterior-posterior sway: Participant sways back and forth with feet planted on ground at a pace/amplitude that is comfortable (discrete)
  • Gluteal clenching: Participant rhythmically tenses and relaxes the gluteal muscles at a pace/duration that is comfortable (discrete)

Participants serve as their own controls and complete both testing arms.

sham comparator: Baseline Stand

Participants will perform a sit-stand test, followed by 5-minutes of baseline (quiet) standing trial on a force platform while cardiorespiratory responses are recorded.

Sit-stand test: following 5-minutes of supine rest, the participant will be passively moved into the seated position. They will then be asked to actively move into the standing position.

Baseline stand: immediately following the sit-stand test, the baseline trial will begin. Participants will stand quietly on the force platform for 5-minutes. This trial will be performed in front of a neutral wall in silence to ensure that visual or auditory stimuli do not affect their movement.

Participants serve as their own controls and complete both testing arms.

Interventions

Counterpressure Maneuvers

Movements that can aid in delaying or preventing syncope by recruiting skeletal muscle pumping (via compression of major veins by contracting muscle to eject blood through cardiovascular circuit) and increased sympathetic drive (via sustaining an isometric muscle contraction). In this trial, we will be evaluating two clinically recommended isometric maneuvers (crouching, and leg crossing with muscle tensing) and two novel dynamic maneuvers that comprise discrete movement that the investigators have identified in prior work (exaggerated anterior-posterior postural sway, rhythmic gluteal clenching).

Baseline Stand

Participants will stand quietly for 5-minutes on a force platform to allow the investigators to assess their typical response to orthostasis.

Primary outcome measure

  • Relationship between postural movement and stroke volume [ Time Frame: Final minute of maneuver performance ]

Central Contacts and Locations

Central contacts

Erin L Williams, BSc

6048976372erin_williams_2@sfu.ca

Victoria E Claydon, PhD

778-782-8513victoria_claydon@sfu.ca

Locations

Simon Fraser University

Recruiting

Burnaby, British Columbia, Canada, V5A1S6

Contacts

Victoria Claydon, PhD

07788588118victoria_claydon@sfu.ca

More Information

Sponsor

Simon Fraser University

Last update posted

Apr 23, 2026

Last verified

Apr, 2026

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by Simon Fraser University on 2026-04-23.