MioAtlas
G4: Congenital heart disease

Patent foramen ovale

Anatomical persistence of virtual communication between both atria at fossa ovalis level due to failure of complete postnatal fusion between septum primum (valve of fossa ovalis) and septum secundum (limbus of fossa ovalis).

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Definition

Anatomical persistence of virtual communication between both atria at fossa ovalis level due to failure of complete postnatal fusion between septum primum (valve of fossa ovalis) and septum secundum (limbus of fossa ovalis). Unlike a true atrial septal defect (where tissue is missing), PFO acts as a flap valve or tunnel that remains closed at rest because left atrial pressure slightly exceeds right atrial pressure, but can open permitting transient right-to-left shunt during transient spikes in right atrial pressure (Valsalva maneuver, coughing, straining) [C5] [G4-01].

Severity criteria

  • Single grade:
    • Anatomical definition without continuous tissue shunt: PFO does not represent a tissue deficiency, but a flap valve; in the absence of pathological elevation of right-sided pressures, there is no continuous left-to-right shunt at rest [C5] [G4-01].
    • Detection and grading of right-to-left shunt (RLS) with Valsalva maneuver: Evaluated by contrast echocardiography during provocative maneuver (Valsalva), graded by number of microbubbles in left atrium within first 3 cardiac cycles: small (3–9 microbubbles), moderate (10–30), and large (>30 or bubble curtain/shower) [G4-01].
    • Absence of resting Qp:Qs figure in the source: Source [G4-01] provides no numerical Qp:Qs figure; value Qp:Qs ≈ 1.0 is a hemodynamic behavior of computational model due to absence of continuous flow.

Findings by layer

Hemodynamics

  • Pulmonary-to-systemic flow ratio: 1.0 at rest (without continuous shunt) [C5].
  • Shunt direction: No shunt at rest; transient right-to-left shunt (right-to-left) during relaxation/release phase of Valsalva maneuver [G4-01].
  • Normal intracavitary pressures (mean right atrial pressure, systolic pulmonary artery pressure normal) [C5] [G4-01].

Rhythm

ECG

Heart sounds and murmurs

  • Heart sounds (S1 and S2): Normal. Physiological splitting of S2 (splits during inspiration and unifies during expiration), unlike the fixed pathological splitting of ASD [G1-11] [G4-01].
  • Murmurs: No audible murmurs at rest or during maneuvers (valvular tunnel generates no audible acoustic turbulence) [G1-14] [G4-01].

Arterial pulse

  • Normal carotid and peripheral pulse [B4].

Jugular venous pulse

  • Normal jugular venous pressure and waveforms [B3].

Maneuvers

  • Valsalva maneuver:
    • During strain phase, venous return to right atrium decreases.
    • Upon release (sudden relaxation phase), abrupt inflow of venous return transiently elevates right atrial pressure above left atrial pressure (RAP > LAP), opening PFO flap and permitting transient passage of venous blood into LA (RA → LA) [G4-01].
  • Respiration: Normal physiological variation of S2 [G1-11].

Simulator severity grades

Simulator severity grades: Single grade
Baseline rhythm: Normal Sinus Rhythm

Also known as: Patent foramen ovale · Persistent foramen ovale · Patent oval foramen · PFO

Other pathologies in this group

Sources

  1. [B1] Bedside diagnosis of systolic murmurs . N Engl J Med (1988) . DOI: 10.1056/NEJM198806163182404 PubMed: 2897627
  2. [B3] The jugular venous pressure revisited . Cleve Clin J Med (2013) . DOI: 10.3949/ccjm.80a.13039 PubMed: 24085809
  3. [B4] The Carotid Pulse . Clinical Methods: The History, Physical, and Laboratory Examinations (1990) . PubMed: 21250154
  4. [C4] 2025 ACC/AHA/HRS/ISACHD/SCAI Guideline for the Management of Adults With Congenital Heart Disease: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines . Circulation (2026) . DOI: 10.1161/CIR.0000000000001402 PubMed: 41411375
  5. [C5] 2020 ESC Guidelines for the management of adult congenital heart disease . Eur Heart J (2021) . DOI: 10.1093/eurheartj/ehaa554 PubMed: 32860028
  6. [E1] AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part V: electrocardiogram changes associated with cardiac chamber hypertrophy: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society: endorsed by the International Society for Computerized Electrocardiology . Circulation (2009) . DOI: 10.1161/CIRCULATIONAHA.108.191097 PubMed: 19228820
  7. [E2] AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society: endorsed by the International Society for Computerized Electrocardiology . Circulation (2009) . DOI: 10.1161/CIRCULATIONAHA.108.191095 PubMed: 19228822
  8. [G1-11] The Second Heart Sound . Clinical Methods: The History, Physical, and Laboratory Examinations (1990) . PubMed: 21250183
  9. [G1-14] Systolic Murmurs . Clinical Methods: The History, Physical, and Laboratory Examinations (1990) . PubMed: 21250186
  10. [G4-01] European position paper on the management of patients with patent foramen ovale. General approach and left circulation thromboembolism . Eur Heart J (2019) . DOI: 10.1093/eurheartj/ehy649 PubMed: 30358849