Patent foramen ovale

What does a foramen ovale do?

A fetus doesn’t use its lungs to get oxygen-rich blood. Instead, it comes from the placenta, delivered through the umbilical cord. Oxygen-rich blood from the umbilical cord enters the fetus’s heart and then uses the foramen ovale as a shortcut.

Taking that shortcut means blood skips the lungs (which aren’t doing anything yet). It goes straight from the heart’s right upper chamber (right atrium) to the left upper chamber (left atrium). From there, the blood eventually pumps out to the fetus’s brain (and everywhere else in its body).

The foramen ovale should naturally close when your baby starts breathing and blood goes to their lungs to get oxygen. The shortcut isn’t needed anymore, so it closes up.

Who might have patent foramen ovale?

Anyone can have patent foramen ovale. But people who need an echocardiogram for certain reasons are more likely to get a diagnosis. That usually affects:

• Divers with decompression sickness (barotrauma): Under high pressure, gases in your blood compress. Fast pressure drops, like in underwater divers who come up too quickly, can make those gases expand and form bubbles. Those bubbles block blood flow.
• People with cryptogenic strokes: About 3 in 10 strokes are cryptogenic, meaning they have an unknown cause. Medical testing after an unexplained stroke often finds a PFO, especially in people under 60. As many as 1 in 2 people under 60 with cryptogenic strokes have a PFO.
• Mountain climbers: A PFO might make you more likely to develop altitude sickness conditions like high-altitude pulmonary edema (HAPE).

How does patent foramen ovale affect my body?

A PFO is a small opening that lets blood leak between your heart’s upper chambers. It’s usually not a problem unless the leak is big enough. When it is, blood clots can slip through the opening. Those clots can either be from:

• Somewhere else in your body: An example of this would be a clot from deep vein thrombosis (DVT) in your legs.
• Within your heart itself: Blood that doesn’t flow properly can pool and start to clot inside your heart. Those clots can easily pass through a PFO and head anywhere in your body.

Clots that make it through a PFO can easily head straight to vital places like your brain. Once there, a clot can get stuck in tiny blood vessels and block blood flow, causing an ischemic stroke. Clots can also get stuck in other critical places, like inside the tiny blood vessels in your kidneys.

PFO usually doesn’t cause symptoms unless the opening is big enough for a lot of blood to pass through. That’s rare, but it can cause:

• Low blood oxygen levels or symptoms of it
• Migraines or migraine-like headaches
• Shortness of breath while sitting or standing (platypnea-orthodeoxia syndrome)
• Ischemia symptoms in your limbs or organs, like your kidneys

It’s much more common for healthcare providers to find a PFO when trying to find a reason why you had a:

• Stroke
• Transient ischemic attacks (often incorrectly called “mini-strokes”)
• Heart attack

Healthcare providers can diagnose PFO with a combination of methods. One easy way they might detect it is by just listening to your heart with a stethoscope (though this isn’t common). Your provider might be able to hear a murmur from the flow of blood through the PFO.

Echocardiograms are the main test to diagnose a PFO. There are two specific types of echocardiogram your provider might recommend:

• Transthoracic echocardiogram (TTE): This type of echocardiogram looks at your heart from outside your body. It uses a wand held to the skin of your chest. Sound waves from the wand help create a picture of the inside of your heart.
• Transesophageal echocardiogram (TEE): This is like TTE, but it looks at your heart from inside your body. Your esophagus passes right next to your heart. That means an echocardiogram probe inserted into your esophagus can get detailed pictures of your heart’s insides.

Your provider may also suggest a bubble test with an echocardiogram or transcranial Doppler (TCD) ultrasound. During a bubble test, they inject saltwater solution into your vein. The TCD ultrasound can detect the bubbles in your head if they pass through the PFO. An echocardiogram can show the bubbles as they pass through a PFO in your heart.