Patent Foramen Ovale – Symptoms and Causes

Overview

A patent foramen ovale is a small opening between the upper chambers of the heart that didn’t close after birth as it should have.

This opening exists naturally in babies before birth, but typically closes during infancy. When it remains open, doctors call it a patent foramen ovale.

Most people with this condition don’t need any treatment. The condition often causes no symptoms or problems. However, for those who do require medical attention, several options exist.

Symptoms

A patent foramen ovale exists in approximately 25% of the population. Most individuals with this condition remain unaware of its presence throughout their lives. The condition is typically discovered accidentally during medical tests performed for other health concerns.

While most cases are asymptomatic, certain situations or complications may raise clinical suspicion for a PFO. You may suspect a PFO if an individual presents with:

Cryptogenic Stroke – a stroke without an identifiable cause, especially in adults under 60.
Transient Ischemic Attacks (TIAs) – stroke-like symptoms that resolve within 24 hours.
Migraine with Aura – recurring migraines that include visual or sensory disturbances, particularly in younger patients.
Unexplained Hypoxemia – low blood oxygen levels that do not improve with oxygen therapy and may worsen when upright (platypnea-orthodeoxia syndrome).
Decompression Illness in Divers – neurological symptoms after diving, due to gas bubbles bypassing the lungs and entering the arterial circulation.
Paradoxical Embolism – evidence of a venous clot or embolus that causes arterial blockages, implying a possible intracardiac shunt like a PFO.

Causes

The heart has four areas: two upper rooms (atria) and two lower rooms (ventricles). The upper chambers collect blood flowing in, while the lower chambers push blood out. Heart valves work like gates, keeping blood moving in one direction only.

Opening Between Heart Chambers

A small flap-like opening can exist between the heart’s upper chambers. This opening usually doesn’t cause problems and rarely needs treatment. Why this happens remains unclear, though genetic factors might play a role.

Normal Heart Function

The heart works in a specific pattern:

Right Upper Chamber (Right Atrium): Collects oxygen-poor blood from the body and sends it through the tricuspid valve to the right ventricle.
Right Lower Chamber (Right Ventricle): Pumps blood to the lungs through the pulmonary artery. Blood picks up oxygen in the lungs before passing through the pulmonary valve.
Left Upper Chamber (Left Atrium): Receives oxygen-rich blood from the lungs through the pulmonary veins and passes it through the mitral valve to the left ventricle.
Left Lower Chamber (Left Ventricle): The heart’s main pumping chamber, sending oxygen-rich blood through the aortic valve and into the aorta, which distributes it throughout the body.

Heart Development Before Birth

Babies in the womb don’t breathe because their lungs aren’t working yet. Instead:

Blood bypasses the lungs
Oxygen comes from the mother through the placenta and umbilical cord
Oxygen-rich blood enters the baby’s heart through the inferior vena cava
Blood flows through the foramen ovale (opening) from the right upper chamber to the left upper chamber
The left ventricle pumps this oxygen-rich blood throughout the baby’s body

Changes After Birth

When a baby takes their first breath, the heart’s blood flow pattern changes:

The lungs begin providing oxygen-rich blood to the heart
This blood enters the left upper chamber
Blood pressure in the heart usually forces the foramen ovale to close
In most people, this opening closes completely during infancy

When this opening fails to close, it’s called a patent foramen ovale. The condition often causes no symptoms and may remain undetected throughout life.

Complications

A patent foramen ovale (PFO) typically causes no health problems for most people. However, some individuals may experience certain complications related to this heart condition.

Potential complications include:

Reduced Oxygen Levels: In rare cases, a PFO can allow blood to bypass the lungs, resulting in lower blood oxygen levels (hypoxemia).
Stroke Risk: Blood clots that form in the veins may sometimes pass through a PFO into the left side of the heart. These clots can then travel to the brain, blocking blood flow and causing an ischemic stroke.

Research has shown some connection between PFOs and unexplained strokes or migraines with aura. However, scientists haven’t fully established a definitive relationship between these conditions.

In many cases, the presence of a PFO alongside these health issues may be coincidental rather than causal.

Most people with a PFO never experience any related health problems. For those who do develop complications, proper medical assessment and treatment can help manage symptoms and reduce risks.