The Cardiovascular Effects of Patent Foramen Ovale in Hypoxia (NCT07742540) | Clinical Trial Compass
Not Yet RecruitingNot Applicable
The Cardiovascular Effects of Patent Foramen Ovale in Hypoxia
50 participantsStarted 2026-09-15
Plain-language summary
Before birth, the foramen ovale is a normal opening in the heart that allows blood to flow from the mother to the baby. After birth, this opening usually closes. However, in up to 38% of the population it does not fully close and is then called a patent foramen ovale (PFO). Having a PFO allows venous (blue) blood to mix with arterial (red) blood in the heart, which can lower blood oxygen levels. The mixing of blood has been suggested to be greater during exercise and with exposure to high-altitude. Also, people with a PFO may be a greater risk for severe altitude sickness, specifically involving the collection of fluid in the lungs which makes breathing very difficult - this is called high-altitude pulmonary edema (HAPE).
No study has directly measured the pressure difference across the heart which is required for the mixing of blood during exercise or at high-altitude. The present study will directly measure the pressure difference across the heart, as well as blood flow through the PFO during rest and exercise in simulated high altitude in adults with and without a PFO and a previous history of severe altitude sickness. The study will test the hypothesis that elevations in pulmonary artery pressure during exposure to hypoxia will not elicit a pressure gradient, and thus blood flow, across the PFO neither at rest nor during exercise.
Who can participate
Age range
18 Years – 60 Years
Sex
ALL
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Inclusion Criteria:
* Males and females age \> 18 but \< 60 years of age at the time of signing the informed consent.
* Medically documented episode of noncardiogenic pulmonary edema occurring after exposure to hypoxia at high altitude.
* No other associated congenital cardiac or vascular abnormalities.
* Physically active, and able to perform endurance exercise.
Exclusion Criteria:
* Do not otherwise meet the inclusion criteria.
* Cardiac- or pulmonary-related medications.
* Known history of anemia, iron deficiency, iron supplementation (oral or intravenous) in the preceding 60 days.
* Systemic anticoagulation or aspirin use that cannot be temporarily held for the study.
* Non-cardiopulmonary disorders that adversely influence exercise ability (e.g. arthritis or peripheral vascular disease).
* Engaging in vigorous physical activity \[≥1 hour at ≥6 mets\] at ≥8,000 ft for \>2 days per week over the preceding 4 weeks, and residing at ≥8,000 ft for 3 or more consecutive nights in the preceding 30 days.
* History of any recent illnesses (e.g. viral respiratory infections) within 4 weeks of testing.
* Women who are pregnant (urine pregnancy test given to all women of childbearing age at the time of testing).
* Other conditions that would limit the patient's ability to complete the study procedures.
Questions worth asking your doctor
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
Questions for the trial coordinator
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
What they're measuring
1
Transmural pressure
Timeframe: During 5 minutes of rest in normoxia, after 15 minutes of exercise in normoxia, after 90 minutes of rest in hypoxia, after 15 minutes of exercise in hypoxia.
2
Arterial oxygen saturation
Timeframe: During 5 minutes of rest in normoxia, after 15 minutes of exercise in normoxia, after 90 minutes of rest in hypoxia, after 15 minutes of exercise in hypoxia.
3
Pulse oxygen saturation
Timeframe: During 5 minutes of rest in normoxia, after 15 minutes of exercise in normoxia, after 90 minutes of rest in hypoxia, after 15 minutes of exercise in hypoxia.
Trial details
NCT IDNCT07742540
SponsorUniversity of Texas Southwestern Medical Center