Medically reviewed by Dr Nabila Laskar, Consultant Cardiologist (GMC 7040901). A patent foramen ovale is a small opening between the upper chambers of the heart that failed to close after birth. Present in approximately one in four adults, it is usually discovered incidentally and causes no symptoms in the majority of people. However, it has gained clinical attention as a potential pathway for stroke in younger adults.
Before birth, the foramen ovale is a necessary opening in the heart's atrial septum that allows blood to bypass the uninflated lungs. In most people, it closes within the first few years of life. In approximately 25 percent of adults, it remains patent (open). In most people this has no clinical consequence. However, when pressure in the right atrium transiently exceeds the left (during straining, coughing, or the Valsalva manoeuvre), blood can shunt momentarily from right to left across the PFO.
The clinical importance of a PFO is primarily in its potential role as a pathway for paradoxical embolism: a clot forming in the venous circulation that would normally travel to the lungs passes instead through the PFO into the arterial circulation and reaches the brain, causing a stroke. This mechanism is thought to be responsible for a proportion of cryptogenic strokes (strokes where no other cause is identified), particularly in younger adults under 60.
An association between PFO and migraine with aura has been documented in research, and some studies suggest PFO closure may reduce migraine frequency in selected patients. However, the evidence is not yet sufficiently strong for routine PFO closure to be recommended solely for migraine.
Echocardiography, particularly transoesophageal echo or contrast bubble echocardiography with a Valsalva manoeuvre, is the primary diagnostic tool. When a PFO is found in the context of a cryptogenic stroke in a young patient, a multidisciplinary discussion involving neurology and cardiology determines whether percutaneous PFO closure is appropriate. In the absence of a stroke or high-risk features, the vast majority of incidentally discovered PFOs require no intervention beyond explanation and reassurance.
Most PFOs found incidentally do not need closure. Closure is considered primarily in younger adults who have had a cryptogenic stroke and where a PFO is identified as the likely pathway.
Approximately one in four adults has a patent foramen ovale. The vast majority never know about it and experience no related symptoms or complications throughout their lives.
Contrast bubble echocardiography with a Valsalva manoeuvre is the most sensitive method. Bubbles injected into a vein are seen crossing from the right to the left atrium if a PFO is present.
A PFO itself does not directly cause palpitations. If palpitations are present alongside a PFO, an alternative explanation such as an arrhythmia should be sought.