Patent foramen ovale: definition, symptoms, diagnosis and consequences

By Cristiano Antonino On May 5, 2023

Patent foramen ovale is a genetic malformation that affects the heart muscle. Commonly this condition is also known as “hole in the heart”, as patients suffering from this condition have an unusual opening at the level of the atria, which connects the right cavity with the left one

This anomaly is the result of incorrect fetal development.

In affected individuals, after birth, the septum primum and septum secundum, i.e. the two membranes located between the walls of the left and right atrium, do not close.

Although it is a potentially very dangerous disorder for the health of an individual, in most cases it occurs asymptomatically; the risks increase significantly when other cardiac anomalies or cardiovascular pathologies arise which can lead to the formation of thromboembolic phenomena, increasing the risk of developing strokes and ischemic attacks.

Precisely for this reason, it is often necessary to intervene surgically to resolve the problem.

Heart anatomy

Before describing the foramen ovale and the mutations associated with it, it may be useful to briefly review some of the main features of the anatomy of the heart.

It is possible to divide the heart muscle into two halves, a left part and a right part; each of the two parts is formed by two cavities within which the blood, the atria and the ventricles flow.

The atrium and ventricle of the same half are connected to each other by the atrioventricular valves: the tricuspid valve on the right side and the mitral valve on the left side.

The atria and ventricles on each side are instead separated by membranous laminae, called septa: the atrial chambers are separated by the interatrial septum, while the ventricular chambers are separated by the interventricular septum; they contribute to the unidirectionality of blood flow, preventing arterial blood and venous blood from mixing.

Deoxygenated blood reaches the right atrium of the heart through the hollow veins; it then passes into the right ventricle and is pumped to the lungs via the pulmonary artery.

The blood thus loaded with oxygen then reaches the left atrium through the pulmonary veins, and then passes into the left ventricle, which has the task of pumping the oxygenated blood to the entire body via the aorta.

The heart movements needed to pump blood are called systole (contracting phase) and diastole (relaxing phase).

What is the foramen ovale

The foramen ovale of the heart (FOP or PFO) is an atrial opening that connects the right cavity with the left one, present in all individuals during the fetal development phase: in this period, in fact, the lungs are not active, and the opening (called the ostium primum) is necessary to allow the passage of blood from the right to the left side of the heart.

The blood flows directly from one right to the left thanks to two openings, the duct of Botallo which is placed between the pulmonary artery and the thoracic aorta, and the foramen ovale which instead connects the two atria.

In most cases, after birth, the foramen ovale, defined up to that moment as patent (i.e. open), should close within the first year of life: when the respiratory activity of the lungs begins, in fact, a difference in pressure between the left atrium and right atrium, which induces the welding of a small membrane called septum primum between the walls of the foramen ovale.

Following the closure of the orifice, a second membrane is created, defined precisely as the septum secundum, which adheres to the first, creating a hermetic closure mechanism that prevents the passage of blood from one part of the heart to the other.

In some individuals, however, anomalies may occur that cause the orifice to fail or partially close; in this case, the separation between the two heart cavities is maintained only by the pressure difference between the right and left sides.

The causes responsible for this defect are not yet fully understood, however it is assumed that a spontaneous genetic mutation is at the origin of the problem.

Patent foramen ovale, symptoms and complications

Many individuals with patent foramen ovale live peacefully with the mutation and do not have significant symptoms.

This is because, as already highlighted, the pressure difference between the two cardiac cavities is sufficient to keep arterial blood and venous blood separate.

However, when the patent foramen ovale is associated with the presence of other heart diseases, valve defects and cardiac arrhythmias, or is combined with other disorders such as cardiovascular and pulmonary diseases, symptoms and even serious complications for the patient’s health can arise.

One of the main risk factors faced by patients with patent foramen ovale is the possibility of developing thromboembolic phenomena.

A deep vein thrombosis phenomenon can occur when a thrombus, formed in the lower limbs, is transported to the right atrium and, due to the presence of this foramen, passes through the interatrial septum reaching the left side of the heart; if the mass enters the circulation, serious arterial occlusions called paradoxical embolisms can occur in the body.

The most frequent consequence is stroke, which occurs when a blood clot reaches an artery that supplies part of the brain.

Furthermore, if a patent foramen ovale is present in patients with heart valve disease or pulmonary hypertension, there can be a considerable reduction in blood flow to the lungs, resulting in hypoxic conditions (i.e. poor blood oxygenation) which can weaken organs and tissues due to lack of oxygen and nutrients.

Diagnosis

As already mentioned, patent foramen ovale in adults is a condition that, in most cases, presents asymptomatically, therefore the diagnosis of this disorder may not be immediate.

To identify this malformation it is necessary to undergo specific tests, such as an echocardiogram: it is an ultrasound examination that allows you to obtain detailed images of the cardiac anatomy, allowing you to identify any anomalies in the cardiac structures, atrial or interventricular defects, valves, myocardial malformations and alterations in the contractile capacity of the heart.

Nevertheless, in some patients, the echocardiogram may not be sufficient to detect the presence of patent foramen ovale; in some cases, therefore, the cardiologist may prescribe further tests, such as:

Color-Doppler echocardiogram: this is a particular ultrasound technique that allows you to analyze in detail the dynamics of blood circulation within the heart cavities.

Echocardiogram with contrast echo: this is a variant of the traditional echocardiogram, which involves injecting a saline solution capable of forming small bubbles into a vein (for this reason it is also called bubble test). Following the blood flow, the bubbles are transported to the heart where, in the presence of an open foramen ovale, they pass directly through the atrial septum and reach the left side of the heart. This test allows you to obtain more precise data than the echocardiogram without contrast, providing more significant information about blood circulation in the heart muscle.

Transesophageal echocardiogram: this type of assessment consists in inserting an ultrasound probe which, passing along the esophagus, is pushed to the area adjacent to the heart. Although it is a more invasive test that can cause some discomfort for the patient, it allows you to obtain clearer images, which are able to highlight some details of the cardiac structures that cannot be identified by other tests.

Care and treatment

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In general, patients with patent foramen ovale are not subject to particular restrictions and can perform any type of activity.

As already underlined, in fact, unless it is associated with other disorders, this condition by itself does not involve any symptoms and, consequently, it is not strictly necessary to intervene to resolve the malformation.

When, on the other hand, the opening of the foramen ovale represents a risk for the patient, it is necessary to proceed with a surgical operation to close the orifice.

There are different approaches for the treatment of this condition: one of the available options is the percutaneous technique, which allows the orifice to be sealed by cardiac catheterization.

It is a micro-invasive approach that allows you to intervene by inserting a small catheter inside a vein, without the risks associated with surgery; the procedure involves closing the orifice by housing a special device, similar to a small umbrella, which closes the channel between the septum primum and the septum secundum.

Alternatively, if it is not possible to proceed with catheterization, it is possible to resort to open heart surgery: this is a decidedly more invasive and not risk-free approach which, however, appears to be the best option for treating patients suffering from additional heart defects.

In some cases, it may be useful to prescribe a drug therapy based on antiplatelet and anticoagulant drugs, to reduce the risk of thromboembolic episodes.

Prevention

Since this is a congenital malformation, it is not possible to prevent this condition, however there are some useful precautions to follow to avoid complications:

During long journeys and particularly sedentary activities, perform some physical exercises to prevent venous stasis;
Perform moderate physical activity regularly;
Drink an adequate amount of water to promote diuresis;
Avoid the intake of alcohol and other vasodilating substances;
Lead a healthy and balanced lifestyle.

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