What are the implications of a patent foramen ovale (PFO) identified on post-natal echocardiogram (echo)?

Patent Foramen Ovale in Postnatal Echocardiography

In the vast majority of neonates and children, a patent foramen ovale (PFO) detected on postnatal echocardiography is a benign finding that requires no intervention, as it represents a normal variant present in approximately 25% of the general population throughout life. 1, 2

Clinical Significance in Pediatric Populations

Normal Developmental Finding

• PFO is the most common congenital heart abnormality of fetal origin, representing a remnant of normal fetal circulation rather than a true pathological defect. 1, 3
• The foramen ovale exists normally in the fetus to direct blood flow from right to left atrium, bypassing pulmonary circulation; its persistence after birth occurs in 25-35% of healthy individuals. 2, 4
• PFO is specifically defined as a small interatrial communication confined to the fossa ovalis region without deficiency of septum primum or secundum, distinguishing it from true atrial septal defects. 1, 5

Pediatric Stroke Considerations

• The significance of PFO and optimal treatment for paradoxical embolism in children with ischemic stroke remains unknown. 6
• There is insufficient research evidence in children with ischemic stroke to support PFO closure. 6
• Unlike adults aged 18-60 years where PFO closure is recommended for carefully-selected stroke patients, no such evidence-based recommendations exist for pediatric populations. 6

When PFO Becomes Clinically Relevant

High-Risk Anatomical Features to Document

• Presence of an atrial septal aneurysm (defined as >10mm excursion of interatrial septum from centerline during cardiac cycle) significantly increases embolic risk. 3
• Atrial septal aneurysm occurs in approximately 2.5% of the general population, most often associated with PFO. 1
• Document the size of the PFO and degree of right-to-left shunting if contrast echocardiography is performed. 1

Potential Mechanisms of Future Complications

• PFO provides anatomic substrate for paradoxical embolization, where venous thrombi can bypass pulmonary circulation and reach systemic arterial circulation. 1, 3
• Thrombus formation can occur on the rim of the PFO defect or on an associated atrial septal aneurysm. 3
• Passage of vasoactive substances that escape pulmonary degradation represents another potential mechanism. 1

Management Approach for Postnatal Detection

Immediate Management

• No intervention is required for isolated PFO detected on routine postnatal echocardiography in asymptomatic children. 6, 2
• Document the finding clearly in medical records for future reference if neurological events occur. 6
• Ensure parents understand this is a common variant, not a disease requiring treatment. 2, 4

Long-Term Surveillance

• Routine follow-up echocardiography is not indicated for isolated PFO in asymptomatic children. 2
• If atrial septal aneurysm is present alongside PFO, consider cardiology follow-up to document stability. 1
• Educate families that PFO becomes clinically relevant primarily in context of cryptogenic stroke, which is exceedingly rare in children. 6

Critical Pitfalls to Avoid

Do Not Overtreat

• Avoid antiplatelet or anticoagulation therapy in asymptomatic children with incidentally detected PFO, as there is no evidence of benefit and potential for harm. 6, 2
• Do not refer for PFO closure in absence of documented paradoxical embolism or stroke. 6
• Recognize that even in adults with stroke, several studies have failed to show increased stroke risk in asymptomatic PFO patients. 2

Distinguish from True Atrial Septal Defects

• Ensure the echocardiographer clearly differentiates PFO (confined to fossa ovalis without septal deficiency) from ostium secundum atrial septal defect (true deficiency of septum primum or secundum). 5
• True atrial septal defects require different management with potential for hemodynamic consequences and closure consideration. 5

Future Stroke Evaluation Protocol

• If the child later presents with cryptogenic stroke or TIA, ensure evaluation by neurologist or stroke specialist to determine if PFO is the most likely cause after excluding alternate etiologies. 6
• Document that thorough etiological evaluation must exclude other causes before attributing stroke to PFO. 6
• Remember that the association between PFO and cryptogenic stroke is strongest in younger patients (<55 years), with odds ratio of 4.70 in young patients versus 2.92 in older patients. 3