Patent Foramen Ovale (PFO): when, how and why to diagnose it

By Cristiano Antonino On Dec 31, 2022

Finding a patent foramen ovale (PFO) in certain clinical scenarios and correcting the defect can prevent strokes

The patent foramen ovale, more commonly known by the acronym FOP or PFO, is the most frequent congenital heart anomaly in adults, being present in 20-34% of the population.

In the vast majority of people, this defect is an entirely benign finding, with no specific symptoms or complaints.

Nevertheless, in some patients it can lead to cerebral ischaemia and systemic embolisation, allowing emboli to transit from the venous to the arterial circulation.

Many clinical studies have been conducted to try to understand how and when to investigate the presence of this anomaly and which patients would benefit most from its treatment.

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What is the patent foramen ovale?

The foramen ovale pervio is nothing more than the persistence of a communication between the right and left atrium that allows, during foetal life, the direct passage of oxygenated blood into the left heart chambers.

In the early post-partum stages, the foramen ovale functionally closes and then completely seals itself in the following months.

In the FOP population, this phenomenon does not fully mature and this communication remains.

Although at rest the passage of blood through the PFO does not occur, under special conditions such as coughing, sneezing or strong physical exertion, the increase in intrathoracic pressure favours the reopening of the foramen ovale, allowing the passage of deoxygenated blood from the right to the left heart chambers.

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When to diagnose PFO (Patent Foramen Ovale)?

Over the years, PFO has been associated with numerous clinical conditions.

However, its very high incidence in the general population may be a confounding factor and its presence, associated with certain diseases, which are also widespread in the general population, may be purely coincidental.

The main pathological conditions in which PFO involvement has been ascertained are cryptogenic cerebral stroke (so defined when the ‘primum movens’ of the ischaemic event cannot be identified), systemic embolism, migraine with aura and decompression sickness in divers.

However, according to the most recent European guidelines, the only true indication for diagnosing and treating FOP is cryptogenic stroke.

How to diagnose PFO?

In the diagnostic procedure for patent foramen ovale, it is essential to proceed with a cardiac ultrasound.

However, an integrated and multidisciplinary approach is often required in order to make a definite diagnosis of a patent foramen ovale and, above all, to identify the main features of the anomaly, allowing appropriate information to be provided for possible correction of the defect.

In particular, the combined use of echocardiogram and trans-cranial Doppler by administering ‘microbubbles’ (mixed saline solution injected through a peripheral venous access) is strongly recommended for the diagnosis of FOP.

Lastly, it is necessary to complete the study of the FOP with a trans-oesophageal echocardiogram to highlight its anatomical features, assess the likelihood that it may favour cerebral ischaemic events and provide useful information for intervention to close the defect.

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Treatment opportunities: percutaneous closure

The patent foramen ovale can be corrected by placing specific prosthetic devices.

By puncturing a peripheral vein, probes are inserted to release the closure device close to the inter-atrial septum, closing the gap between the right and left atrium.

The procedure is performed under local anaesthesia and the device is released under intracardiac or trans-oesophageal ultrasound guidance.

The procedure is characterised by a high probability of success and low incidence of complications.

The hospital stay usually lasts about 24-36 hours.

However, it should be pointed out that the procedure does not aim to improve the patient’s symptoms, but rather to act preventively, reducing the risk of stroke recurrence.

The patent foramen ovale still represents a challenge in terms of clinical relevance, the need to diagnose and treat it

Only recently has scientific evidence confirmed that correction of this defect prevents the recurrence of cerebral ischaemic events in patients with a positive medical history of cryptogenic stroke.

Still, future studies will certainly clarify the pathogenetic role of FOP in pathologies such as headache with aura and decompression syndrome, opening possible diagnostic-therapeutic scenarios.