Patent foramen ovale

A patent foramen ovale (PFO) is a type of atrial septal defect in which there is channel-like communication between the atria through an unfused fossa ovale.

The foramen ovale in the interatrial septum normally develops into the fossa ovalis when the flaps of the atrial septa primum and secundum normally fuse during development. The foramen ovale remains patent if there is incompletely fusion. This variant occurs in 25-33% of adults 1,2. The prevalence may decrease with advancing age.

Patent foramen ovales/foramina ovalia are subdivided into:

  • probe-patent foramen ovale
  • patent foramen ovale

A "probe patent" foramen ovale is defined as a defect in the fossa ovalis that would be revealed with instrument probing.

A patent foramen ovale has been associated with paradoxical embolism and ischemic stroke because of the potential for a venous thromboembolism to pass from the right atrium to the systemic circulation, bypassing the lungs.

PFOs are small enough to be haemodynamically insignificant.

  • may be detected on a "bubble study" (IV injection of agitated saline); the contrast material appears in the left atrium before the normal time
  • abnormal communication of contrast material between the atria through a channel-like tunnel in the interatrial septum
  • a channel-like tunnel alone is a normal variant of the fossa ovalis, and is not diagnostic
  • not a first-line study, but may be diagnosed by visual assessment or computation of signal–time curves in the pulmonary vein and the left atrium 3

A patent foramen ovale can be differentiated from an atrial septal defect because a PFO takes a tunneled intraseptal course, or with the presence of a flap valve on the left atrial side of the foramen 2

Closure devices, both surgically open and percutaneous, have been developed and are currently implemented in some centers for PFO.

Congenital heart disease

There is more than one way to present the variety of congenital heart diseases. Whichever way they are categorised, it is helpful to have a working understanding of normal and fetal circulation, as well as an understanding of the segmental approach to imaging in congenital heart disease.

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Article information

rID: 31984
System: Cardiac
Section: Anatomy
Synonyms or Alternate Spellings:
  • PFO

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Cases and figures

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    Case 1
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    Case 2: closure device on chest x-ray
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