Patent Foramen Ovale

What is Patent Foramen Ovale?

A patent foramen ovale (PFO) is part of a group of heart conditions known as atrial septal defects, and it is actually a normal part of an infant’s heart structure. In fact, more than half of infants still have a PFO when they are six months old. Usually, it doesn’t create any major health issues in newborns, and it may even stay with them into adulthood. Most adults with a PFO don’t have any symptoms. However, in some adults, the PFO can cause a mix-up in the heart’s flow, sending blood that hasn’t been refreshed with oxygen from the right side of the heart to the left. This mix-up can also result in a blood clot (thromboembolism) being sent from the veins to the arteries. Certain health conditions are linked to having a PFO, such as having a stroke without a clear cause (cryptogenic stroke), decompression sickness (a condition that can occur in divers), migraines, a syndrome that causes difficulty breathing when standing up (platypnea-orthodeoxia syndrome), and a sudden loss of blood flow to a limb due to a blood clot (acute limb ischemia). These are all explained by the changes that a PFO can cause in the heart’s blood flow.

What Causes Patent Foramen Ovale?

The foramen ovale is a small, tunnel-like space found between two parts of the heart, known as the septum secundum and the septum primum. This space is particularly important during a baby’s development in the womb, as it guides blood flow across a particular part of the fetal heart. It also helps richly oxygenated blood – which the baby gets from the mother’s placenta – move from the large vein known as the inferior vena cava, through the foramen ovale, and into the baby’s circulation system.

In approximately 75% of babies, this space naturally closes as the two sections fuse together. However, in around 25% of people, this space – known as a PFO or patent foramen ovale – remains open into adulthood.

People with a PFO may sometimes also have associated conditions such as:

* Atrial septal aneurysms: These occur when there’s an excess of tissue in the wall dividing the two upper chambers of the heart.
* Eustachian valves: These are remnants of a valve that was important during fetal development.
* Chiari networks: These are thread-like structures in the right upper chamber of the heart.

A PFO that is clinically significant can cause two potential problems:

* It can act as a pathway for a clot or other material from the veins to pass into the body’s overall circulation system. This is known as a paradoxical embolization.
* Since PFOs have a tunnel-like structure that slows down blood flow, clots may form inside this space. It’s important to know that not all PFOs cause problems and that many people with a PFO lead normal, healthy lives. If a PFO causes issues, treatment options are available.

Risk Factors and Frequency for Patent Foramen Ovale

In 1988, studies found that 30% to 40% of young patients who had a stroke with no determined origin, also known as a cryptogenic stroke, had a condition called a Patent Foramen Ovale (PFO). This figure is higher than the 25% found in the general population. Over time, this incidence has increased, especially in patients of any age with cryptogenic stroke, where the presence of PFO is almost double that found in the general population.

However, it’s unclear what the best preventive strategy is for adults with PFO. This uncertainty is particularly relevant for patients with PFO and an additional condition known as atrial septal aneurysm who have had strokes. These patients seem to have a higher chance of having another stroke – as high as 15% per year, which means that preventive measures are crucial.

• In another study, half of the patients with cryptogenic stroke were found to have a condition where blood can flow from the right to the left side of the heart (known as right-to-left shunting) compared to only 15% in the control group.
• About two-thirds of divers who experienced decompression sickness without an obvious cause were found to have a PFO.

Signs and Symptoms of Patent Foramen Ovale

Patients with a Patent Foramen Ovale (PFO) usually don’t show any symptoms, but in some cases, it can lead to serious problems. These can include severe headaches similar to migraines, symptoms related to decreased blood flow to the brain or other essential organs like the arms, legs, kidneys, or intestines. This reduced blood flow can cause a stroke-like event. Some of the less common symptoms can be a blood clot that moves to another part of the body, a heart attack, a blockage of an artery in another part of the body, or shortness of breath when at rest. The physical examination usually doesn’t indicate any unusual findings. Occasionally, a soft whooshing sound, known as a faint systolic murmur, might be heard during the heartbeat due to abnormal blood flow.

• Severe migraine-like headaches
• Signs and symptoms of decreased blood flow to essential organs
• Less common symptoms include blood clots, heart attack, blockage of an artery, or shortness of breath
• Faint systolic murmur during a physical examination (rare)

Testing for Patent Foramen Ovale

Doctors typically start looking for a PFO (Patent Foramen Ovale, a hole in the heart that didn’t close the way it should after birth), when a patient experiences a cryptogenic stroke. A cryptogenic stroke is a type of stroke where the cause is unknown despite extensive investigation. A PFO might also be spotted unintentionally during heart scans (echocardiograms) done for other reasons, especially in newborn babies.

A PFO is commonly identified via different types of heart scans: transthoracic echocardiography, transesophageal echocardiogram (TEE, a test that uses sound waves to create high-quality moving pictures of the heart), or transcranial Doppler (a test that checks the blood flow in the brain). The most precise test is TEE, especially when it’s supplemented with a contrast agent (a special dye that makes certain areas show up better on the scan). It often involves the patient coughing or bearing down like they’re trying to have a bowel movement (a maneuver called Valsalva) while the scan is being done. However, TEE can be challenging and may need sedation, which makes it less suited for newborns and children.

If a newborn with a heart disease is suspected to have a PFO, the examination should provide a thorough description of the presence of a PFO, its size, and whether it affects blood flow or pressure. Patients who’ve had a cryptogenic stroke should also be checked for blood clots in the veins (venous thromboembolism or VTE). This is crucial because having a PFO could increase the chances of blood clots, which could enhance the risk of stroke and impact the person’s overall health.

Similar tests should be performed for divers who’ve experienced more than one undeserved decompression illness (a condition where body tissues are affected by a sudden drop in pressure around you). In 2015, a gathering of diving medicine experts recommended a special type of heart scan called contrasted provocative transthoracic echocardiography. This test has fewer complications than TEE and is unlikely to miss a clinically significant PFO.

Again, patients who’ve had a cryptogenic stroke should also be evaluated for venous thromboembolism (VTE) to understand the associated risk of blood clots linked with PFO. This can influence the impact on their health and survival rate.

Treatment Options for Patent Foramen Ovale

A patent foramen ovale (PFO), which is a small hole in the heart that didn’t close the way it should after birth, doesn’t usually require any treatment or check-ups in newborns and children. In fact, it plays an essential role in some congenital heart conditions where there needs to be a flow of blood at the atrial or upper chamber level of the heart. However, if an adult has a PFO and experiences unexplained strokes, treatment might be needed.

There are several treatment options available:

1. Medications – Aspirin is often used to prevent blood clots, especially in those who had a stroke due to a blood clot that traveled to their brain (an embolism). If the stroke is linked to a blood clot in a vein (venous thrombosis), anticoagulant medications or blood thinners may be given to prevent more clots.

2. Percutaneous device closure – This is a procedure where a small device is inserted through a blood vessel and guided to the heart to close the PFO. Multiple studies have shown this is better than only using medication to reduce the risk of having another stroke, especially in patients under 60 years old. The FDA has approved certain specific devices for this procedure. It is performed under X-ray guidance and may require hospital stay. Patients undergoing this procedure may need to take Aspirin or a blood thinner, like warfarin, for at least six months.

Sometimes, a surgical approach is needed to close the PFO. Instances for such a decision could be:
* If the PFO is larger than 25 mm
* If the non-surgical approach (percutaneous closure) didn’t work
* If the edges of the PFO make it hard to close through percutaneous closure

Surgery can ensure complete closure of PFO and might remove the need for long-term blood thinners. However, it involves open-heart surgery and carries the usual risks associated with such procedures.

What else can Patent Foramen Ovale be?

Patent Foramen Ovale, or PFO, is a common feature in both newborns and adults. When diagnosing, however, other congenital heart diseases need to be ruled out. These can include:

• Atrial Septal Defect: Unlike a PFO, there’s an actual hole in the wall between the heart’s upper chambers, and a particular type of heart sound (fixed split-second heart sound) can usually be heard during a checkup.
• Ventricular Septal Defect: This can be in the membranous or muscular part of the heart’s wall, and is usually linked with an overarching heart murmur that lasts throughout the entire beat of the heart (pansystolic murmur).
• Patent Ductus Arteriosus: This is another heart connection existing during fetal development necessary for circulation in the womb, which may stay open (or “patent”) in newborns, and less commonly into childhood. This is usually associated with a constant, machine-like murmur.

What to expect with Patent Foramen Ovale

In newborns and children, the outlook for a condition known as PFO (Patent Foramen Ovale – a hole in the heart that didn’t close the way it should after birth) is generally very good, and the hole often closes on its own. For older children and adults who need surgery to close the hole because of the risk of blood clots, the outlook is also positive. The success of these surgeries has been well-documented.

There’s a non-surgical procedure that can close the hole, called a percutaneous closure, which shows promise but does sometimes come with complications. These can include blood clots, the device used to close the hole moving out of place, and the hole not closing fully. Additionally, the percutaneous procedure could potentially cause damage to the blood vessels, stroke, clot formation, and infective endocarditis – which is an infection of the inner lining of your heart chambers and heart valves.

Possible Complications When Diagnosed with Patent Foramen Ovale

The primary risks associated with antiplatelet and anticoagulant therapies are bleeding and brain hemorrhages. While using device closure, potential complications include severe bleeding due to perforation, the development of air or device emboli, and strokes. However, these complications are very rare, typically occurring in less than 1% of cases in experienced hands. Temporary heart rhythm disorders may occur in about 3% to 5% of cases after the procedure. Some devices are associated with a 5% to 6% risk of developing atrial fibrillation, a common type of irregular heartbeat, often linked to clot formation. There have been isolated cases of late cardiac perforation with some devices, but this is extremely rare. In comparison, atrial fibrillation is more commonly seen in closure patients than in patients on blood thinners for secondary preventive strategies.

Potential Complications:

• Bleeding
• Brain hemorrhages (intracerebral hemorrhages)
• Severe bleeding due to perforation
• Air embolism (air bubble obstructing blood flow)
• Device embolization (device moving to block a blood vessel)
• Stroke
• Temporary atrial arrhythmias (heart rhythm disorders)
• Atrial fibrillation associated with thrombus formation
• Late cardiac perforation