The Cardiovascular Effects of Patent Foramen Ovale in Hypoxia
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- This is an observational study: the protocol does not assign a study treatment.
- Who it may be relevant to
- Registry conditions: Patent Foramen Ovale (PFO), High Altitude Pulmonary Edema. Basic parameters: 18 years — 60 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Center list to be confirmed — check the primary protocol.
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
Unsure about the terms? Read our patient guide →
Official title
The Role of Patent Foramen Ovale on Cardiac Hemodynamics and Exercise Cardiac Reserve in HAPE-susceptible Individuals
Overview
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.
Primary outcome measures
- Transmural pressure [Time frame: 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 [Time frame: 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 [Time frame: 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 outcome measures (6)
- Gas exchange [Time frame: 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 [Time frame: 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 [Time frame: 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 [Time frame: 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 [Time frame: 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 [Time frame: 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.]
Eligibility criteria
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.
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: Yes
Study design
- Observational model
- Case-control
Study locations
Center list to be confirmed — check the primary protocol.
Identifiers
NCT: NCT07742540 · STU-2026-1373 · Herbert N. Hultgren Grant