Patent foramen ovale is a common heart opening that did not fully close after birth, and many people with patent foramen ovale never notice any problems. It may help to know that doctors have studied this condition for decades, and in most cases it is found by chance in adults during a scan or evaluation for another issue. Some people with patent foramen ovale are diagnosed after a stroke with no clear cause, migraines, or low blood oxygen, but not everyone will have the same experience. Patent foramen ovale is usually lifelong unless it is closed with a catheter-based procedure, and many people do not need treatment at all. Death from patent foramen ovale itself is uncommon, and care focuses on monitoring, blood-thinning medicine for selected people, or closing the opening when the risk of complications is higher.
How many people live with Patent foramen ovale?
Patent foramen ovale is very common: using the widely cited estimate that it is present in about 1 in 4 people, this suggests roughly 2 billion people worldwide, although that is an estimate rather than a direct count (American Heart Association, 2024; United Nations, 2024). Using the same estimate, about 84 million people in the United States may be living with a patent foramen ovale (American Heart Association, 2024; U.S. Census Bureau, 2024).
Overview
Patent foramen ovaleSymptoms
Patent foramen ovale usually causes no symptoms, and many people never know they have it. When problems happen, they are often linked to a stroke, mini-stroke, or migraine with aura rather than the opening itself.
Outlook and prognosis
For many, a patent foramen ovale causes no symptoms and does not shorten life expectancy. When treatment is needed, outlook is usually very good, though people with stroke, migraines, or other heart conditions may need closer follow-up.
Causes and risk factors
Patent foramen ovale happens when a normal opening between the heart's upper chambers does not fully close after birth. Risk is slightly higher with a family history, while lifestyle and environmental factors do not appear to be major causes.
Genetic influences
Genetics may play a modest role in patent foramen ovale. It can run in families, but no single gene usually explains it. In most people, other developmental and chance factors also matter.
Diagnosis
Patent foramen ovale is usually found with an echocardiogram, often using bubble contrast. Doctors may also use a transesophageal echo or, less often, other heart imaging. The diagnosis of patent foramen ovale depends on imaging findings, not symptoms alone.
Treatment and drugs
Many people with patent foramen ovale need no treatment. If it is linked to stroke or severe low oxygen, doctors may use blood thinners or close the opening with a catheter device. Care depends on symptoms and stroke risk.
Symptoms
Most people living with patent foramen ovale feel normal and never know it is there. For many people with patent foramen ovale, there are no day-to-day symptoms at all. When signs do happen, they are usually related to a blood clot crossing the opening or, more rarely, to lower oxygen levels. Some people first hear about a PFO after testing for a stroke, migraine, or another heart concern.
Most people with patent foramen ovale do not feel anything unusual in daily life. The early features of patent foramen ovale are often no features at all, and it may only be found during a scan done for another reason.
In some people, a small blood clot can pass through the opening and travel to the brain. This can cause sudden weakness, numbness, trouble speaking, vision loss, or a transient ischemic attack, which is a short-lived stroke-like episode.
Some people with patent foramen ovale also have migraines, especially migraines with aura such as flashing lights or zigzag lines before the headache. A PFO does not explain every migraine, but this link has been seen often enough to matter in some cases.
Rarely, patent foramen ovale can let enough blood bypass the lungs to lower oxygen levels. This may cause shortness of breath, lightheadedness, or bluish lips that are worse when sitting or standing and better when lying down.
How people usually first notice Patent foramen ovale?
Many people with patent foramen ovale, a small flap-like opening between the heart’s upper chambers that did not fully close after birth, do not notice anything at all at first, and it is often found by chance during a heart scan done for another reason. When patent foramen ovale is first noticed because of symptoms, it is often after an unexplained stroke or transient ischemic attack, sometimes called a mini-stroke, especially in a younger adult without the usual stroke risk factors. Less often, the first signs of patent foramen ovale involve low blood oxygen, shortness of breath that gets worse when sitting or standing, or problems linked to pressure changes such as decompression illness in divers.
Types of Patent foramen ovale
No distinct types of patent foramen ovale are widely recognized.
Can I slow down the onset of symptoms?
Not really: a patent foramen ovale, which is a small opening between the heart’s upper chambers that is present from birth, does not usually cause symptoms, and there is no proven lifestyle change that meaningfully delays symptoms from starting. Research has not shown that diet, exercise, sleep, or supplements can prevent a PFO from causing problems, although not smoking and keeping overall heart and blood vessel health in good shape may help lower the risk of related complications such as a stroke, which is different from preventing the PFO itself. If someone has already had a stroke or another clot-related problem thought to be linked to the PFO, doctors may consider blood-thinning medicine or a procedure to close the opening; for many others, the best step is simply good routine care and knowing that most people with a PFO never develop symptoms.
What genetics can tell you about symptoms
For most people with a patent foramen ovale, genetics does not clearly predict whether symptoms will happen, how severe they might be, or when they would start, because many people never have symptoms at all. There may be some inherited tendency for this opening between the upper heart chambers to persist in families, but no single gene is used in routine care to forecast day-to-day effects. When symptoms or related problems do occur, they are usually shaped more by the size of the opening and whether it allows blood clots or blood flow changes to pass through than by a known genetic pattern.
Causes and risk factors
A patent foramen ovale usually happens because a small flap between the heart’s upper chambers does not seal fully after birth. This is a common birth difference, and it is not usually caused by anything a parent did during pregnancy. It can run in families, so genes may play a part, but researchers are still learning how these pieces fit together. Biological factors such as a larger opening or higher pressure on the right side of the heart can make symptoms or problems more likely. Lifestyle and environmental factors do not usually cause patent foramen ovale, but smoking, long periods of immobility, and estrogen-containing medicines can raise stroke risk in people with patent foramen ovale.
What are the most common causes or risk factors?
A patent foramen ovale happens when a small flap-like opening between the heart’s upper chambers, which everyone has before birth, does not fully close after birth. The exact reason is usually not known, but it can run in families, so inherited genes may play a part, and it is sometimes seen along with other heart differences present from birth. There are no well-proven lifestyle risk factors, and nothing a parent or child did caused it.
Environmental and biological risk factors
For most people with patent foramen ovale, there is no single clear reason why it occurs. Doctors often group risks into internal (biological) and external (environmental), but for patent foramen ovale the best-supported factors are mostly tied to early heart development and birth timing.
Patent foramen ovale is most closely linked to how the heart develops and adapts around birth. In many cases, the usual sealing process after delivery does not fully happen, even without a known external trigger.
Babies born before full term may have a higher chance that the opening remains unsealed after birth. The pressure changes in the heart and lungs that help normal closure can be less settled in early-born infants.
Patent foramen ovale is sometimes seen alongside other heart differences present from birth. This suggests that shared biological factors during fetal heart formation may play a role in some cases.
No specific environmental exposure has been clearly proven to cause an isolated patent foramen ovale. Researchers are still exploring how outside influences interact with our inner biology. Most cases happen without an identifiable exposure during pregnancy.
Genetic risk factors
Most people with patent foramen ovale do not notice anything day to day, and many find out only after a scan for another reason. Patent foramen ovale can cluster in families, which suggests that inherited factors can affect how the small flap between the heart’s upper chambers closes after birth. Some risk factors are inherited through our genes.
Family history: Patent foramen ovale appears more often in some families than would be expected by chance alone. This often leads people to ask whether patent foramen ovale runs in families, and the answer is that it can, although the pattern is not usually simple or predictable.
Heart formation genes: Genes that guide how the heart’s upper chambers and the tissue between them form before birth may influence whether the opening seals fully after birth. In most people with patent foramen ovale, no single gene change is identified.
Complex inheritance: Patent foramen ovale is usually thought to result from several inherited factors acting together rather than one clear genetic cause. People with the same risk factor can have very different experiences.
Related heart traits: In some families, patent foramen ovale is seen alongside other inherited structural differences in the wall between the heart’s upper chambers. When this happens, the shared pattern supports a genetic contribution, even if testing does not find one specific change.
Lifestyle risk factors
Patent foramen ovale is present from birth, so lifestyle habits do not cause it. However, how lifestyle affects patent foramen ovale can matter because certain behaviors can raise the chance of blood clots, pressure changes, or low oxygen states that make complications more likely. The main concerns are stroke, transient ischemic attack, decompression illness in divers, and symptom worsening in a small subset of people. Lifestyle advice is most relevant when someone has had a prior clot-related event or has other medical risk factors.
Smoking can increase blood clotting tendency and damage blood vessels, which may raise the chance that a clot could cross a patent foramen ovale and trigger a stroke. Stopping smoking is one of the most important ways to lower this complication risk.
Long periods of sitting and very low activity can promote blood pooling in the legs and increase the risk of venous clots. Regular movement, walking, and leg exercises are especially important during travel or recovery periods because they may reduce the chance of a clot reaching the heart.
Excess body weight is linked to higher risks of venous thromboembolism, sleep apnea, and strain on the heart and lungs. In people with a patent foramen ovale, these effects can make clot-related or low-oxygen complications more likely.
Dehydration can thicken the blood slightly and may contribute to clot formation, especially during heat exposure, illness, endurance activity, or long travel. Staying well hydrated may help lower one of the practical lifestyle risk factors for patent foramen ovale complications.
Risk prevention
Many people with patent foramen ovale never know they have it and do not need any special prevention. Because a patent foramen ovale is a small opening in the heart that is present from birth, there is no proven way to prevent the opening itself from existing. Prevention usually means lowering the chance of problems linked to patent foramen ovale, especially certain strokes, and keeping your heart and blood vessels as healthy as possible. Prevention is flexible—it adapts to your life and health background.
If you have a patent foramen ovale, regular medical follow-up can help your care team judge whether it is likely to stay harmless or needs closer attention. This matters most if you have had a stroke, a mini-stroke, or early symptoms of patent foramen ovale such as unexplained migraine with aura or fainting that needs evaluation.
For some people with patent foramen ovale, especially after a stroke with no other clear cause, doctors may recommend aspirin, another blood thinner, or a closure procedure. The right choice depends on your age, stroke history, bleeding risk, and the shape of the opening.
Long periods of sitting can raise the risk of clots forming in the legs, which can matter more in people with patent foramen ovale. On long trips, get up to move, flex your calves, stay well hydrated, and ask your doctor if compression socks are a good idea for you.
Smoking harms blood vessels and raises the risk of stroke and blood clots, which can make patent foramen ovale more concerning. Quitting can lower that risk over time, even if you have smoked for years.
Can you prevent Patent foramen ovale?
No, there is no known way to prevent a patent foramen ovale, which is a small opening between the heart’s upper chambers that does not fully close after birth. It develops before birth, and there is no proven link to everyday habits or anything a parent clearly did or did not do. For most people, the focus is not on prevention but on whether it needs any follow-up or care.
Transmission
Patent foramen ovale is not infectious, so it cannot be passed from person to person through the air, by touch, through sex, or in food or water. Instead, patent foramen ovale is a common heart opening present from birth that stays partly open after delivery, usually because of how the heart develops very early on.
When people ask how patent foramen ovale is inherited, the answer is that it can run in some families, but it usually does not follow a simple parent-to-child pattern. For many living with patent foramen ovale, this means relatives do not automatically have it, although a family history may slightly raise the chance.
When to test your genes
For a patent foramen ovale, genetic testing is not routinely used because this common heart opening is usually found by imaging, not DNA. Testing may be worth discussing if you or close relatives have early stroke, unusual blood clots, or signs of an inherited connective tissue or clotting disorder.
Diagnosis
Patent foramen ovale is often found by chance when someone has a heart scan for another reason, but it may also be looked for after an unexplained stroke, migraine with aura, or low oxygen levels. Doctors usually begin with your symptoms, medical history, and the reason testing was ordered, because the diagnosis of Patent foramen ovale depends on showing a small flap-like opening between the heart’s upper chambers. Some diagnoses are clear after a single visit, while others take more time.
Your clinician asks about stroke or mini-stroke symptoms, migraines, shortness of breath, and any past blood clots. A detailed family and health history can help show whether another heart or blood-vessel problem might better explain what is going on.
This standard heart ultrasound is often the first imaging test. It can show the heart’s structure and may suggest a Patent foramen ovale, especially when combined with a bubble study.
During the scan, saline with tiny bubbles is injected into a vein while the heart is imaged. If bubbles pass from the right side of the heart to the left, that supports the diagnosis of Patent foramen ovale.
If the usual ultrasound is not clear enough, your provider may suggest a transesophageal echocardiogram to look closer. This test places an ultrasound probe in the esophagus, giving a more detailed view of the atrial wall and the opening.
How is Patent foramen ovale diagnosed?
Patent foramen ovale is usually diagnosed with an ultrasound of the heart, called an echocardiogram, which lets the doctor look for a small opening between the heart’s two upper chambers. Often, a simple “bubble test” is added, where harmless tiny bubbles are injected into a vein to see whether blood is passing through that opening; sometimes a closer scan is done with a small probe passed down the food pipe after numbing medicine or light sedation. Genetic testing is not used to diagnose a patent foramen ovale.
Stages of Patent foramen ovale
Patent foramen ovale does not have defined progression stages. This is because it is a structural opening in the heart that is either present or not, rather than a condition that usually moves step by step over time. Many people feel relief once they understand what’s happening, especially since patent foramen ovale often causes no symptoms and is commonly found during testing after a stroke, a migraine workup, or another heart check. Doctors usually confirm it with heart imaging, such as an echocardiogram, and follow-up depends on your history, including whether there have been symptoms of patent foramen ovale or problems like an unexplained stroke.
Outlook and prognosis
For most people, the outlook with a patent foramen ovale is excellent, and many live their entire lives without symptoms or health problems. Mortality is generally not increased by an isolated patent foramen ovale itself, especially when it is found incidentally and there is no history of stroke, low oxygen levels, or other heart disease. The main prognostic concern is a small increased risk of paradoxical embolism, which can contribute to cryptogenic stroke in selected individuals, although the absolute risk remains low for most people. In patients who have had a stroke thought to be related to a patent foramen ovale, prognosis is often still good with appropriate treatment, which may include antiplatelet therapy, anticoagulation in some cases, or device closure. Closing the defect can reduce the risk of recurrent stroke in carefully chosen patients, but it does not improve outcomes for everyone with a patent foramen ovale. Overall prognosis depends more on age, prior stroke or clotting events, and coexisting cardiovascular conditions than on the presence of the opening alone.
Long-term effects
For many people, Patent foramen ovale causes no lasting health problems and is found only by chance during a scan or heart test. The long-term picture is often shaped by whether it stays silent or is linked to problems such as stroke, migraine, or low blood oxygen. Some may never notice any day-to-day effect, while others need long-term follow-up because the long-term effects of Patent foramen ovale can differ a lot from one person to another.
Many people with Patent foramen ovale live their whole lives without any clear health consequences from it. In these cases, it does not shorten life expectancy or lead to ongoing disability.
A small number of people with Patent foramen ovale have a higher long-term risk of stroke or transient ischemic attack, sometimes called a mini-stroke. This risk matters most when a blood clot can cross from the right side of the heart to the left and then travel to the brain.
Some living with Patent foramen ovale also have migraines, especially migraines with aura. Research shows an association in some people, but not everyone with Patent foramen ovale gets migraines, and not all migraines are caused by it.
In uncommon cases, Patent foramen ovale can contribute to lower blood oxygen levels, especially when body position or certain lung conditions change blood flow through the heart. Over time, this may lead to breathlessness or tiredness in daily activities such as climbing stairs or walking uphill.
How is it to live with Patent foramen ovale?
For many people living with a patent foramen ovale, daily life feels completely ordinary because this small flap-like opening in the heart often causes no symptoms at all and is found only by chance. If it has been linked to a stroke, a transient ischemic attack, or sometimes migraine in your situation, living with it can mean follow-up visits, possible blood-thinning medication, and conversations about travel, diving, or other activities that may slightly change pressure in the body. Around you, the biggest effect is often worry rather than visible illness, and family members may simply need reassurance, support during medical appointments, or extra help if a stroke has affected day-to-day function.
Treatment and drugs
Many people with patent foramen ovale, or PFO, never need treatment and only learn about it after a scan done for another reason. When treatment is needed, it is usually because a PFO may be linked to a stroke, low blood oxygen levels, or certain symptoms that tend to happen in specific situations, and the main options are blood-thinning medicine or a procedure to close the opening with a small device passed through a blood vessel. Doctors choose between these options based on your age, medical history, and whether another likely cause for the problem has been found. Not every treatment works the same way for every person, and some living with patent foramen ovale do well with monitoring alone while others benefit from closure. Ask your doctor about the best starting point for you.
Can you cure Patent foramen ovale?
A patent foramen ovale, which is a small opening between the heart’s upper chambers that did not close after birth, often does not need a cure at all, and many people never need treatment. There is no medicine that makes it close, but doctors can often close it with a procedure done through a blood vessel, and only rarely with surgery, if it has caused problems or is linked to a higher stroke risk. Treatment is mainly meant to lower the chance of future problems, not because this opening always causes symptoms.
Non-drug treatment
Many people with patent foramen ovale never need active treatment and simply have regular follow-up, especially if it was found by chance and has not caused problems. When treatment is needed, the main non-drug approach is closing the opening with a catheter-based procedure rather than medicine alone. Other care often focuses on lowering stroke risk, supporting recovery after a stroke, and helping people return safely to daily life.
If a patent foramen ovale is found incidentally, careful monitoring may be all that is needed. This usually means follow-up with a heart specialist and a plan to reassess if symptoms or a stroke-like event occurs.
This procedure places a small closure device through a thin tube, usually inserted in the groin, to seal the opening without open-heart surgery. For some people, especially those needing treatment for patent foramen ovale after stroke, it can lower the chance of another stroke when the PFO is thought to be a likely cause.
Surgery is rarely used just for a patent foramen ovale on its own. It may be considered if someone is already having heart surgery for another reason and closing the opening at the same time makes sense.
If a patent foramen ovale has been linked to a stroke, rehabilitation can be a key part of recovery. Supportive therapies can include physical, occupational, and speech therapy to help with walking, hand use, communication, and day-to-day tasks.
Your genes may have an impact on how drugs work for you
For patent foramen ovale, medicines are usually used to lower the chance of blood clots and stroke, and inherited differences can sometimes change how well some blood-thinning medicines work or how likely they are to cause bleeding. For example, many living with a PFO may break down certain anti-clot medicines too slowly or too quickly, so one person gets less protection while another has more side effects. This kind of gene-based drug response, sometimes called pharmacogenomics, is not the main issue for most people with a PFO, but it can matter in some cases, especially after a stroke or after a heart procedure to close the opening.
Pharmacological treatments
Treatment for patent foramen ovale often focuses on lowering the risk of blood clots and stroke rather than treating the opening itself with medicine. Many people living with patent foramen ovale do not need any drugs, while others may be offered medication after a stroke, a transient ischemic attack, or after a closure procedure. Not everyone responds to the same medication in the same way, so the choice depends on your medical history, bleeding risk, and why treatment is being considered.
Aspirin is one of the most common medicines used for patent foramen ovale when doctors want to reduce the chance of small blood clots forming. It makes platelets less sticky, which can help lower the risk of another stroke in some people.
Clopidogrel is another antiplatelet drug that may be used instead of aspirin, or sometimes together with it for a limited time after PFO closure. For some people with early signs of stroke linked to patent foramen ovale, it may be part of the plan to help prevent another event.
Anticoagulants such as warfarin, apixaban, rivaroxaban, and dabigatran may be used when clot risk is higher, especially if there is a history of venous blood clots or another reason for full blood thinning. These drugs work differently from aspirin and usually require a careful balance between stroke prevention and bleeding risk.
Heparin or low molecular weight heparin may be used short term in hospital settings when doctors need rapid anticoagulation. This is usually a temporary step rather than a long-term treatment for patent foramen ovale.
Genetic influences
When a patent foramen ovale turns up on a heart scan, many people wonder whether it runs in families. It’s natural to ask whether family history plays a role. Research suggests genes may help shape how the wall between the heart’s upper chambers closes after birth, so inherited factors may make a patent foramen ovale more likely in some families. At the same time, most people with patent foramen ovale do not have a single known gene change that explains it, because this opening forms very early in development and often happens without one clear cause. Rare inherited conditions that affect connective tissue or heart development can include a patent foramen ovale or similar openings, but that is not the usual reason. Because of this, genetic testing is not a routine part of care for patent foramen ovale, although several relatives with the same finding or other heart defects may be a reason to talk more with your doctor.
Is Patent foramen ovale genetic?
Genetics may play a modest role in patent foramen ovale. It can run in families, but no single gene usually explains it. In most people, other developmental and chance factors also matter.
Having a genetic risk is not necessarily a diagnosis
Genetic changes, often called variants, are a normal part of human biology and are very common across the general population. Most of these variants do not have a direct effect on health and are simply part of normal human diversity. For many genes, carrying a variant connected with a condition suggests a possible link rather than a certain diagnosis, especially when more than one gene and environmental factors are involved. In some situations, however, a single well-understood variant in a specific gene is enough to confirm a diagnosis.
Pharmacogenetics—how genetics influence drug effects
Many living with patent foramen ovale never need medicine at all, while others may be offered aspirin, another blood thinner, or a closure procedure after a stroke or mini-stroke. Because patent foramen ovale is a structural opening in the heart, genetics usually do not determine whether the opening itself should be closed. Not every difference in response is genetic, but inherited traits can matter when blood-thinning treatment is part of care. For example, some people have gene changes that make clopidogrel less effective because their body does not activate the drug as well. Genes can also affect the dose of warfarin that is safest and most effective, so in selected situations doctors may consider genetic testing for blood thinners in patent foramen ovale, although this is not routine for everyone. Other factors, such as why the PFO is being treated, past stroke or clotting problems, age, kidney function, and bleeding risk, are often just as important as genetics when choosing treatment.
Interactions with other conditions
Most people with patent foramen ovale have no day-to-day symptoms, but it can matter more when other health issues are present. In some people, a patent foramen ovale may raise the chance that a blood clot can pass from the right side of the heart to the left and then travel to the brain, which is why it is sometimes found during the workup after a stroke or mini-stroke with no clear cause. It can also interact with migraine, especially migraine with aura, although the link is still being studied and closing the opening does not reliably help everyone. Doctors call it a “comorbidity” when two conditions occur together. People with certain lung or heart pressure problems, including pulmonary hypertension, may have more strain from a patent foramen ovale because blood can move in the wrong direction more easily, sometimes leading to lower oxygen levels. This is also why related issues such as sleep apnea, deep vein blood clots, or rare decompression illness in divers can become more relevant, and if you are asking whether patent foramen ovale can cause other problems, the answer depends a lot on your overall health, age, and whether you have had early symptoms of patent foramen ovale such as unexplained stroke-like events.
How genes can cause diseases
Humans have more than 20,000 genes, each carrying out one or a few specific functions in the body. One gene instructs the body to digest lactose from milk, another tells the body how to build strong bones and another prevents the body's cells from beginning to multiply uncontrollably and developing into cancer. As all of these genes combined are the building instructions for our body, a defect in one of these genes can have severe health consequences.
Through decades of genetic research, we know the genetic code of any healthy/functional human gene. We have also identified that in certain positions on a gene, some individuals may have a different genetic letter from the one you have. We call these hotspots "Genetic Variations" or "Variants" in short. In many cases, studies have been able to show that having the genetic letter "G" in the position makes you healthy, but having the letter "A" in the same position disrupts the gene function and causes a disease. Genopedia allows you to view these variants in genes and summarizes all that we know from scientific research, which genetic letters (Genotype) have good or bad consequences on your health or on your traits.
What other conditions can cause similar symptoms to Patent foramen ovale?
Because a patent foramen ovale often causes no symptoms at all, problems linked to it may actually be due to something else. Stroke-like symptoms, such as sudden weakness, numbness, trouble speaking, or vision changes, can also happen from an irregular heartbeat called atrial fibrillation, narrowed blood vessels going to the brain, blood-clotting problems, or another hole between the heart’s upper chambers. If the main issue is migraine or shortness of breath, those also have many more common causes, so doctors usually check for those first.
History
Many people with patent foramen ovale, often shortened to PFO, have no symptoms at all and only hear about it after a heart scan done for another reason. For some, it comes up after an unexplained stroke, repeated mini-strokes, or during an evaluation for migraines or low oxygen levels. That everyday reality shaped its history: for a long time, doctors knew the small flap-like opening could persist after birth, but they were not always sure when it truly mattered.
Early anatomists recognized that this opening is a normal part of blood flow before birth, when a baby’s lungs are not yet being used for breathing. As medical science evolved, doctors came to understand that the opening usually closes soon after birth, but in some people it stays partly open. For many years, this was often treated as an interesting finding rather than a condition needing much attention, because most people living with a PFO remained well.
That view began to shift as heart ultrasound improved and doctors could see the opening more clearly in living patients, not just during autopsy. In recent decades, awareness has grown as researchers studied whether patent foramen ovale might help explain some strokes that happen without an obvious cause, especially in younger adults. This did not mean every PFO was dangerous, but it pushed medicine to look more carefully at who might be at higher risk and who would not benefit from treatment.
Modern research has made the picture more nuanced. Doctors now understand that patent foramen ovale is common, that most people will never know they have one, and that decisions about treatment depend on the full situation, not the finding alone. That history matters because it helps explain why some may be told a PFO is simply something to note, while others are offered medicines or a procedure to close it after a stroke or another serious event.