Where is a Patent Foramen Ovale (PFO) located?

Patent Foramen Ovale (PFO) Location

A patent foramen ovale (PFO) is located in the interatrial septum of the heart, forming a communication between the right and left atria. 1

Anatomical Details

The PFO represents a specific type of interatrial communication with distinct characteristics:

• Origin: PFO is a remnant of the fetal circulation that persists after birth 1
• Structure: Forms a flap or tunnel-like communication in the atrial septum 2
• Specific location: Located in the central portion of the interatrial septum
• Configuration: The PFO consists of two components:
  • The septum primum (a valve-like flap on the left atrial side)
  • The septum secundum (forming the rim on the right atrial side)

Diagnostic Visualization

The PFO can be visualized through several imaging techniques:

• Transesophageal echocardiography (TEE): The gold standard for PFO detection 3

  • Provides direct visualization of the interatrial septum
  • Allows assessment of the anatomical characteristics of the PFO
  • Bubble study demonstrates right-to-left transit of contrast microbubbles through the interatrial communication

• Transthoracic echocardiography (TTE): Less sensitive but useful for initial screening 3

  • Can detect larger PFOs but may miss smaller defects

Clinical Significance of PFO Location

The interatrial location of PFO has important clinical implications:

• Paradoxical embolism: The location allows venous thrombi to bypass pulmonary filtration and enter the arterial circulation 1
• Cryptogenic stroke: PFOs are found in higher prevalence among patients with cryptogenic stroke compared to the general population 1
• Anatomical variations: The specific characteristics of the PFO location can affect stroke risk:
  • PFOs associated with atrial septal aneurysm (a redundant and hypermobile portion of the interatrial septum) may pose higher risk 1
  • The size of the opening and the magnitude of right-to-left shunting can influence clinical significance 1

Prevalence and Natural History

• Present in approximately 25-30% of the general population 4, 2
• Prevalence appears to decrease with age 1
• In most individuals, the PFO location poses no health threat 4, 2

Diagnostic Confirmation

The diagnosis of PFO is established by:

• Demonstration of an interatrial communication with right-to-left transit of contrast microbubbles within 3 to 4 cardiac cycles of right atrial opacification 1
• The Valsalva maneuver during testing increases detection sensitivity by transiently raising right atrial pressure 3

Understanding the precise anatomical location of PFO is essential for proper diagnosis and management of potential associated conditions, particularly in patients with cryptogenic stroke.