Cardiology

Understanding Your Heart's Connection: ASD and PFO

At a Glance

An interatrial communication is an opening between the heart's upper chambers. An ASD is a permanent hole, while a PFO is a flap that didn't seal after birth. Most cases require only monitoring, but problematic openings can be safely fixed with minimally invasive, non-surgical procedures.

Learning that you or your child has a heart “defect” can feel overwhelming, but it may help to know that interatrial communications—connections between the two upper chambers of the heart—are incredibly common ^[1]^[2]. In fact, one type is present in about a quarter of all people, and most lead full, healthy lives without even knowing it ^[2]^[3].

An interatrial communication simply means there is a way for blood to pass between the left atrium (the chamber that receives oxygen-rich blood from the lungs) and the right atrium (the chamber that receives oxygen-poor blood from the body) ^[4].

Two Types of Connections

While they are often mentioned together, an Atrial Septal Defect (ASD) and a Patent Foramen Ovale (PFO) are physically different.

ASD: The “True Hole”

An ASD is a literal hole in the wall (the septum) that separates the upper chambers ^[4]. It occurs when that wall doesn’t form completely during development ^[4].

How common is it? About 2 out of every 1,000 babies are born with an ASD ^[2]. It is one of the most frequent heart conditions diagnosed at birth ^[1].
What happens? Because pressure is higher on the left side of the heart, blood tends to flow through the hole from left to right ^[1]. This is called a shunt ^[5]. Over many years, this extra blood can cause the right side of the heart to work harder and become enlarged ^[5]^[6].

PFO: The “Flap”

A PFO is not a missing piece of the heart wall, but rather a flap-like door that didn’t seal shut after birth ^[4]. Every baby is born with this opening because it is necessary for blood circulation in the womb ^[7]. In most people, it zips shut shortly after birth, but in some, it remains “patent” (open) ^[4].

How common is it? Roughly 25% of the general adult population has a PFO ^[2].
What happens? Most of the time, a PFO stays closed because the pressure on the left side of the heart keeps the flap pressed shut ^[8]. However, certain actions (like a heavy cough or straining) can momentarily raise pressure on the right side, pushing the flap open ^[8]^[9].

Understanding the Risks

Doctors look at these connections differently because they affect the body in different ways.

Feature	Atrial Septal Defect (ASD)	Patent Foramen Ovale (PFO)
Physical Form	A permanent hole ^[4]	A flap-like tunnel ^[4]
Primary Concern	Hemodynamic shunting: Too much blood flowing to the right side of the heart ^[5].	Paradoxical embolism: A tiny blood clot crossing the flap and traveling to the brain or body ^[10].
Long-term Effect	Can lead to heart enlargement or lung pressure issues if large ^[5]^[11].	Usually causes no symptoms; rarely associated with stroke risk in specific adults ^[12]^[13].

The Road Ahead

The “good news” regarding these diagnoses is that the medical community has a very clear understanding of how to manage them.

Monitoring: Many small ASDs and almost all PFOs require nothing more than occasional check-ups ^[3]^[14]. In infants, some ASDs may even close on their own over time ^[15].
Simple Repairs: If a hole is large enough to cause concern, it can often be fixed without major surgery ^[16]. Doctors can use a percutaneous closure, where a small, umbrella-like device is guided through a vein to plug the opening ^[16]^[17]. This procedure is considered very safe and effective ^[16].
Normal Life: For the vast majority of children, an isolated ASD or PFO does not limit their ability to play, grow, or lead a completely normal life ^[3].

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Common questions in this guide

What is the difference between an ASD and a PFO?

An Atrial Septal Defect (ASD) is a permanent hole in the wall separating the heart's upper chambers. A Patent Foramen Ovale (PFO) is a natural flap-like opening that fails to seal shut completely after birth.

Is a hole in the heart dangerous?

Many small ASDs and almost all PFOs cause no symptoms and simply require regular monitoring. However, larger ASDs can lead to heart enlargement, and PFOs are rarely associated with stroke risk in specific adults.

Will my child need open-heart surgery to fix an ASD?

Not necessarily. If a hole is large enough to require treatment, doctors can often use a minimally invasive percutaneous closure. This involves guiding a small device through a vein to plug the opening without major surgery.

What symptoms should I watch for if I have an ASD or PFO?

While many people experience no symptoms, you should monitor for unusual fatigue, shortness of breath, or frequent respiratory infections. If you notice any of these changes, it is important to discuss them with your cardiologist.

Can a PFO or ASD close on its own?

Some smaller Atrial Septal Defects diagnosed in infants may close on their own over time as the child grows. Patent Foramen Ovales typically do not close on their own in adulthood, but most never require treatment.

Get notified when new evidence is published on Interatrial communication.

We monitor PubMed for new peer-reviewed studies on this topic and email a short summary when something meaningful changes.

References (17)

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This page provides educational information about interatrial communications (ASD and PFO). It is not a substitute for professional medical advice, and you should always consult your cardiologist regarding your specific diagnosis and treatment options.