Patent Foramen Ovale (PFO)NCT07742540
The Cardiovascular Effects of Patent Foramen Ovale in Hypoxia
An observational study of Patent Foramen Ovale (PFO) and High Altitude Pulmonary Edema, run by University of Texas Southwestern Medical Center.
Trial 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). Read more about this study
- Who is it for?
- Ages 18 to 60 yearsHealthy volunteers can take part
- Conditions the study is for
- Patent Foramen Ovale (PFO), High Altitude Pulmonary Edema
- How many people
- 50 participants
- Where
- No sites listed yet
- Study dates
- 15 Sep 2026to 15 Sep 2028
- Phase
- Observational
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 60 years
- All sexes
- Healthy volunteers accepted
- Adult
Study population: Individuals with documented history of high-altitude pulmonary edema and with or without a patent foramen ovale
Who may be able to join
- 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.
Who cannot join
- 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.
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- 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.
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: The Role of Patent Foramen Ovale on Cardiac Hemodynamics and Exercise Cardiac Reserve in HAPE-susceptible Individuals
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.
- Keywords
- hypoxia, altitude, heart, high altitude pulmonary edema, patent foramen ovale, exercise, pulmonary artery pressure, intracardiac pressures, right-to-left shunt
- Medical subject headings
- Foramen Ovale, Patent, Altitude Sickness, Hypoxia, Motor Activity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| HAPE+PFO | Adults with documented history of high-altitude pulmonary edema and a patent foramen ovale | |
| HAPE | Adults with documented history of high-altitude pulmonary edema |
What is being measured
The primary outcome is the main question the study is designed to answer.
Transmural pressure
Absolute difference between pulmonary capillary wedge pressure and right atrial pressure
Measured: 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.
Arterial oxygen saturation
Measured: 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.
Pulse oxygen saturation
Measured: 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.
Secondary outcomes (6)
Gas exchange
Oxygen uptake and carbon dioxide production
Measured: 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.
Arterio-venous oxygen different
Measured: 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.
Cardiac output
Measured: 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.
Right ventricular diameter
Measured: 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.
Tricuspid regurgitant jet velocity
Measured: 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.
Tricuspid annular plane systolic excursion
Measured: 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.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Aug 2026
- Study start15 Sep 2026 (estimated)
- Primary completion31 Dec 2027 (estimated)
- Study completion15 Sep 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Patent Foramen Ovale (PFO)Studies of the same condition, open and under way.
- 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
- Observational
- Observational model
- Case-control
- Time perspective
- Prospective
- Enrolment
- 50 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Texas Southwestern Medical Center
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Benjamin Levine, University of Texas Southwestern Medical Center
- Investigators
- Benjamin D. Levine, M.D., Principal investigator, The University of Texas Southwestern Medical Center Dallas
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07742540
- Sponsor's protocol ID
- STU-2026-1373
- Other IDs
- Herbert N. Hultgren Grant
- Status last verified
- Jul 2026
- First submitted
- 20 Jul 2026
- Last updated
- 3 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No