Pervio Oval Foram

Generality

The patent foramen ovale ( FOP ) is an anatomical defect of the heart, characterized by an unusual opening in the septum that separates the two atria (right and left).

Figure: PFO is the English acronym of Patent Foramen Ovale, which means patent foramen oval. From the site: health.sjm.com

Although FOP is a potentially serious abnormality, most of those affected do not complain of any associated disorder and lead a completely normal life. The drawbacks arise only when other anatomical alterations of the heart or particular cardiovascular diseases accompany the interatrial defect.

At present, the precise causes of FOP are unclear. According to some scholars, the origin could be a genetic mutation.

For a correct diagnosis, an echocardiogram must be performed.

In the absence of other heart defects, the patent foramen ovale does not require any special treatment.

A brief reference to the anatomy of the heart

Before describing the patent oval foramen, it is useful to retrace some fundamental characteristics of the heart.

With the help of the image, readers are reminded that:

The heart is divided into two halves, right and left. The right heart is composed of the right atrium and the right ventricle below. The left heart is composed of the left atrium and the left ventricle below. Each atrium is connected to the underlying ventricle by means of a valve .
Each half of the heart is separated from the other half by laminae, called septa: the two atrial chambers are separated by means of the interatrial septum (thinner and completely membranous), while the two ventricular chambers are separated by means of the interventricular septum (much more often it is made up of a membranous mars and a muscular one). The presence of the interatrial and interventricular septa prevents the mixing between arterial blood and venous blood.
The right atrium receives non-oxygenated blood through the cavities .
The right ventricle pumps blood into the pulmonary artery, which leads to the lungs. In the lungs, the blood is charged with oxygen.
The left atrium receives oxygenated blood, returning from the lungs, through the pulmonary veins .
The left ventricle pumps oxygenated blood to the organs and tissues of the human body, through the aorta .
Each ventricle communicates with its efferent vessel by means of a valve. Therefore, there are four heart valves in all.

What is the patent oval foramen?

The patent foramen ovale (or FOP or PFO ) is an interatrial defect of the heart, characterized by the presence of an abnormal orifice which puts the right atrium in communication with the left atrium.

According to another definition, the patent foramen ovale is the result of the failed closure of the septum primum and of the septum secundum of the heart, after birth.

INTERACT SECTOR FORMATION

During fetal development, the heart is extremely different from how it appears at birth and later in life.

The two cardiac atriums, in fact, communicate with each other by means of an opening delimited by two sketches of the wall, the so-called septum primum (from the left atrium) and septum secundum (from the right atrium).

In reality, initially there is only one septum (the primum ) and the opening that communicates the two atria is called simply ostium primum . The septum secundum is generated shortly after and, on the occasion of its formation, the opening changes, giving rise to the oval foramen of Botallo (on the side of the right atrium) and to the ostium secundum (on the side of the left atrium).

At birth, the child still has the Botallo oval foramen and the ostium secundum, but as soon as it begins to breathe, the opening closes. The closure takes place thanks to the blood that returns from the lungs, as the latter favors the adhesion of the septum primum to the septum secundum .

When we talk about patent oval foramen, we refer to the patency formed by the oval foramen of Botallo and the ostium secundum .

Formation of the Botallo oval foramen and of the ostium secundum in the fetus. From the site: revespcardiol.org

HEART OF THE FETUS AND FETAL CIRCULATION

As long as the baby is in the mother's womb, it receives oxygenated blood from the mother, as it cannot breathe.

Maternal oxygen-rich blood flows into the inferior vena cava, through the so-called umbilical vein . From the inferior vena cava, it reaches the right atrium, where in large quantities it takes the oval foramen of Botallo and goes, first, in the left atrium and, then, in the left ventricle. When found in the left ventricle, it is pumped into the ascending aorta and led mainly to the upper parts of the body (brain and upper limbs).

Figure: blood circulation in the fetus. From the site: lyceum.algonquincollege.com

The small amount of maternal blood that passes to the right ventricle is mixed with the one that comes from the superior vena cava and takes the pulmonary artery. However, the pulmonary artery of the fetus has a duct (the so-called arterial duct ), which puts it in communication with the descending aorta . Through the descending aorta, blood irrigates the lower parts of the body (abdominal organs and lower limbs).

When a child is born, in addition to closing the interatrial opening, the ductus arteriosus also closes. This causes the blood to travel the normal pathway that leads to the lungs and can oxygenate itself regularly.

Epidemiology

The patent oval foramen is part of a group of heart disorders called interatrial heart defects . According to some statistical surveys, the patent oval foramen affects 20-25% of adults (about one in four).

However, it must be remembered that this last datum is not very reliable, since FOP is often asymptomatic and, for this reason, not diagnosed. In other words, the actual number of individuals with FOP is likely to be much higher.

Causes

The causes of patent foramen ovale are, at the moment, unclear.

According to some researchers, there may be a genetic mutation at the origin of the anomaly.

However, this hypothesis still has some question marks to elucidate.

Symptoms and Complications

Many individuals with patent oval foramen are fine and do not present any disturbance. Therefore, this cardiac anomaly is almost always asymptomatic .

The possible appearance of symptoms and pathological signs usually depends on the concomitant presence of other heart diseases (defects of the heart valves, arrhythmias, etc.) or non cardiac (pulmonary disorders, etc.).

COMPLICATIONS

According to some scientific research (however, still in the process of being defined), the FOP would seem to be linked to the appearance of migraine with aura .

Furthermore, according to other studies, the simultaneous presence of a neoplasm and FOP would predispose the patient to the formation of blood clots capable of causing stroke episodes.

Another problem could be in case of deep vein thrombosis ; in this case, a thrombus formed in a vein of the lower limbs could be transported to the right atrium and from here - due to an abnormal pressure (eg pulmonary embolism) - to cross the atrial septum migrating to the left side of the heart and entering so in the systemic circulation. In such situations a severe arterial occlusion called paradoxical embolism could be generated.

Finally, if the patent oval foramen is accompanied by diseases of the heart valves ( valvulopathies ) or pulmonary hypertension, the proportion of blood directed to the lungs could be significantly reduced. This results in less blood oxygenation ( hypoxia ).

Diagnosis

The diagnostic examination of choice to highlight a patent foramen ovale is the echocardiogram .

The echocardiogram is an ultrasound examination that shows, in detail, the anatomy of the heart and any anomalies of the latter. It allows, in fact, to identify interatrial and interventricular defects, valvular defects, myocardial malformations (ie the heart muscle) and heart pumping difficulties.

The echocardiogram is a simple and non-invasive examination, which involves the use of a sound wave probe ( transducer ) and a non-toxic gel. The latter is applied to the patient's chest to obtain better echographic images.

ECOCARDIOGRAM: THE VARIANTS

Sometimes, a simple echocardiogram can be of little significance and not clearly show the FOP.

To avoid this inconvenience, doctors can use one or more of the following variants:

Color- Doppler echocardiogram . It is a traditional echocardiogram that allows to study also the exact dynamics of blood flow through the heart valves and inside atria and ventricles.
It is called " color " because, based on different colors, it distinguishes the direction and speed of circulating blood currents in the heart.
Echocardiogram with eco-contrast or " bubble test " . Before carrying out the traditional echocardiogram, the doctor injects into a peripheral vein of the patient (usually in the arm) a saline solution capable of forming small bubbles. Getting carried away by the venous blood circulation, the bubbles reach the heart and, if the interatrial septum presents the FOP, they pass directly from the right atrium to the left atrium. If the septum is intact, they are directed towards the lungs.
The echocardiogram is able to clearly show the movements of the bubbles, providing more significant results than those emerging from an examination without echo-contrast.
Since an injection is planned, the " bubble test " is considered a minimally invasive procedure.
Transesophageal echocardiogram . During this type of echocardiogram, the ultrasound probe is inserted into the esophagus, through the mouth. From here, the images provided by the transducer are very clear and allow to highlight different details, which with the previous procedures may not be noticed.
However, the greater precision has its price: the exam, in fact, is annoying and somewhat invasive.

Treatment

The patent oval foramen can be solved by closing the interatrial opening, by means of an appropriate intervention. However, most people with POF lead a normal life and need no treatment.

When is it then necessary to intervene?

REASONS FOR THE INTERVENTION

The reasons that push a surgeon to operate a subject with patent foramen ovale are:

In a child, the simultaneous presence of other more serious and congenital heart defects (ie present from birth).
In an adult, the onset of a serious heart problem, which requires surgery.
The need to alleviate the state of hypoxia, which is created due to the lack of blood supply to the lungs.
In case of recurrent stroke and not explainable by other causes.

Since the association between FOP and migraine with aura is still unclear, doctors advise against an opening closure operation for these reasons.

PROCEDURES FOR CLOSING

The possible therapeutic procedures for closing the patent foramen ovale are:

Figure: closing of the oval shape with a catheter and umbrella. From the site: trihealth.com Closing by cardiac catheterization (or percutaneous closure) . During this procedure, the doctor closes the patent oval foramen thanks to a small parasol, which, once opened, covers the patency present between the septum primum and the septum secundum .
The umbrella is placed at the desired point by means of a catheter, that is a small flexible tube capable of crossing the larger veins of the body and entering the heart. Catheter insertion usually occurs in a groin vein and its entry into the heart is monitored by transesophageal echocardiography.
Once the umbrella is housed and made sure that the FOP is closed, the operating doctor extracts the catheter and the ultrasound probe. The entire procedure lasts 1-2 hours and is less invasive than surgery.
Surgical repair . The closing of the patent oval foramen occurs after the surgical incision of the chest; in other words, through an " open heart " intervention.
Surgical repair is certainly an invasive and risk-free practice; however it is very useful in all those cases in which the patient suffers from further heart defects. In fact, all abnormalities of the heart are often repaired with a single operation.

PHARMACOLOGICAL THERAPY

Individuals with patent foramen ovale and predisposed to the formation of blood clots are subjected to anticoagulant therapy (warfarin, rivaroxaban, dabigatran etexilate etc.) and antiplatelet agent (clopidogrel and aspirin).

The purpose of these assumptions is to prevent episodes of stroke or, at least, to reduce their probability.

SOME ADVICES

Those who know they suffer from patent foramen ovaries are advised, when they make long air or car journeys, to take all necessary precautions to prevent venous stasis (which can facilitate the formation of blood clots in the veins). Therefore, it is good practice: take short walks, drink water regularly and perform simple mobility exercises for the legs and hips.