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Screenings by age and gender

Small hole in the heart (PFO) found by chance

An echocardiogram or bubble test done for another reason may report a "patent foramen ovale" or "PFO". This is a small flap-like opening between the two upper chambers of the heart that is open before birth and usually closes soon after. (Clin Med 2022) About 1 in 4 adults have one, and in most cases it is entirely benign. (SCAI 2022) This page covers what the report means and the signs that need help, not treatment.

What the report means

  • What it is. Before birth, the foramen ovale lets blood bypass the lungs. It stays open in up to 25% of people when the two layers of the wall between the upper chambers do not fully join. (Clin Med 2022)
  • Usually no symptoms. Most people with a PFO have no symptoms and do not need any treatment. (Clin Med 2022)
  • Stroke risk on its own. A 2018 review says a PFO by itself has not been shown to raise the risk of ischemic stroke. (Collado 2018) The 2024 European stroke guideline says only a small minority of people with a PFO have a stroke linked to it in their lifetime. (ESO 2024)
  • Size varies. In an autopsy study the opening measured 1 to 19 mm, 1 to 10 mm in 98% of cases, and tended to be larger at older ages. (Hagen 1984)

How a PFO shows up

  • Bubble test. A small amount of shaken salt water is injected into an arm vein during an echocardiogram. Bubbles that reach the left side of the heart within 3 heartbeats point to a hole between the upper chambers. (Collado 2018) The test may be done at rest and again while you strain, as if blowing out against a closed mouth. (Clin Med 2022)
  • Size of the shunt. There is no single accepted grading. One scheme calls fewer than 5 bubbles small, 5 to 25 medium and more than 25 large. (Clin Med 2022)
  • Other tests. A scan through the gullet (transoesophageal echo) gives the clearest view, and a Doppler test of blood flow in the head can also detect bubbles. (Clin Med 2022)(ESO 2024) No single test catches every PFO: the guideline found the gullet scan missed about 1 in 10 compared with firm reference standards. (ESO 2024)

How common it is by age

In an autopsy study of 965 normal hearts, evenly spread by sex and age, a PFO was found in 27.3% overall, with no difference between men and women. It was found in 34.3% of people in their first 3 decades, 25.4% from the 4th to the 8th decade and 20.2% in the 9th and 10th decades. (Hagen 1984)

What guidance says when there has been no stroke

  • No treatment in most cases. The 2022 SCAI guideline says a PFO is in most cases entirely benign and needs no treatment. (SCAI 2022)
  • No routine screening. A 2022 Royal College of Physicians review says routine screening for PFO is not recommended. (Clin Med 2022)
  • When it matters more. The guidance is mainly about people who have had a stroke with no other clear cause, and about some divers and people with certain rare symptoms; these need a specialist review. (ESO 2024)(SCAI 2022) A higher share of people with migraine with aura have a PFO than the general population. (Clin Med 2022)

How it ties to your age-based checks

MedlinePlus says the risk of stroke rises with age and lists high blood pressure as the main risk factor. (MedlinePlus) A PFO found by chance does not change the routine checks for your age, and it is a good time to make sure they are up to date:

Other heart and brain findings have their own pages: mild leaky heart valve on an echocardiogram, enlarged heart on a chest X-ray and white matter changes on a brain MRI.

Who it applies to

Adults told that an echocardiogram or bubble test done for another reason shows a PFO. Children, people who have had a stroke or mini-stroke (TIA), and people with other heart defects followed by a specialist are outside this page. See screenings after a stroke.

NHS, call 999 (911 in the US) now if you think you are having, or have had, a stroke, or you have had signs of a stroke in the last 24 hours even if they have stopped. (NHS)(MedlinePlus) Remember FAST:

  • Face: one side may droop and it may be hard to smile
  • Arms: you may not be able to lift both arms and keep them there
  • Speech: words may be slurred or confused
  • Time: to call 999 (911 in the US)

Other signs include weakness or numbness down one side, blurred vision or loss of sight, confusion, feeling dizzy or falling over, and a severe headache. Do not drive yourself to A&E. (NHS)

Routine age-based screening

A finding on an echocardiogram does not replace the routine screenings for your age. See screenings by age and gender.

Where they differ:

  • How common. The ESO, SCAI and the 2018 review use about 25% of adults; the autopsy study found 27.3% overall, falling from 34.3% in young people to 20.2% in the oldest. (ESO 2024)(SCAI 2022)(Collado 2018)(Hagen 1984)
  • The best test. The 2018 review says testing should start with a bubble echocardiogram through the chest. (Collado 2018) The Royal College of Physicians review says a PFO is best seen on a transoesophageal echo, while the ESO guideline notes that this test still misses some. (Clin Med 2022)(ESO 2024)
  • Grading the shunt. The ESO guideline calls more than 20 bubbles a large shunt on an echo, while the scheme in the Royal College of Physicians review uses more than 25. (ESO 2024)(Clin Med 2022)

Your doctor decides what your result means for you.

Questions people ask

How common is a PFO?

Very common. Guidance from European and American bodies puts it at about 25% of adults, or about 1 in 4. An autopsy study of 965 normal hearts found it in 27.3%, with fewer open holes at older ages. (ESO 2024) (SCAI 2022) (Hagen 1984)

Does a PFO mean I will have a stroke?

No. A 2018 review says a PFO by itself has not been shown to raise the risk of ischemic stroke, and the 2024 European stroke guideline says only a small minority of people with a PFO have a stroke linked to it in their lifetime. (Collado 2018) (ESO 2024)

Do I need more tests or follow-up?

Usually not just for the finding. SCAI says a PFO is in most cases entirely benign and needs no treatment, and a 2022 Royal College of Physicians review says most people with one have no symptoms and that routine screening for PFO is not recommended. Your doctor decides. (SCAI 2022) (Clin Med 2022)

What is a bubble test?

It is an echocardiogram with a small amount of shaken salt water injected into an arm vein. If bubbles reach the left side of the heart within 3 heartbeats, that points to a hole between the upper chambers. (Collado 2018) (Clin Med 2022)

What stroke signs need help straight away?

The NHS lists face drooping, arm weakness and speech problems (FAST), and advises calling 999 (911 in the US) if you think you are having or have had a stroke, even if the signs have stopped. (NHS) (MedlinePlus)

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