What is an open oval window, when and why is it dangerous?

What is this defect and what is its physiology?

An open foramen ovale in the heart of a newborn is a normal variant. What is it for? Blood circulation in the fetus starts at the beginning of the second trimester of pregnancy. Like an adult, a baby’s heart has four chambers:

1. In the third week of intrauterine development, there is already a wall separating the atria - the primary interatrial septum (PAS) with a wide opening.
2. In the fifth week of pregnancy, it overgrows, but a new one appears - a secondary one (opposite which an oval window is formed in the child’s heart), and another wall is formed to the right of the primordial septum.
3. By the end of the seventh week, the primary MPP turns into a valve covering the oval window.

The fetus does not breathe, and its “point of gas exchange” is the placenta, therefore, the body does not need a pulmonary circulation. Instead it has:

• ductus arteriosus - a vessel connecting the aorta to the pulmonary artery;
• Foramen ovale is the opening between the ventricles.

The unborn baby receives oxygenated blood from the mother's placenta, from where it flows through the two umbilical arteries into the inferior vena cava. Venous blood from the baby’s internal organs also enters there. This mixed blood (arterial for the mother and venous for the fetus) flows into the right half of the heart.

The window between the atria is necessary for maximum blood flow into the left chambers of the heart, and then into the aorta. The remaining blood in the right atrium is sufficient to oxygenate the lung tissue.

How the pulmonary circulation turns on

With the first cry, when the mother's oxygenated arterial blood stops flowing, the newborn's carbon dioxide concentration increases. Vascular receptors “signal” about hypoxemia to the respiratory center of the brain. From there, the impulse goes to the skeletal muscles of the ribs, under the influence of which it expands. The pressure inside the chest cavity decreases, and a stream of air rushes into the lungs, thereby straightening them.

At the moment of the first breath:

• The pressure inside the left atrium increases significantly.
• The valve is pressed against the oval window.
• The communication between the atria is blocked.
• The flows of arterial (from the lungs) and venous (from the internal organs) blood no longer intersect.

Two circles of blood circulation begin to function. Subsequently, the septum secundum is fused to the wall of the heart. In most people, a fossa ovale forms at the site of the oval window.

Two things at once

Similar operations are currently performed in many countries around the world. However, in Russia the technique has been improved. During an intervention to close the interatrial orifice in adults and especially elderly patients, specialists also evaluate the condition of the heart vessels. The development of atherosclerosis in them is the most important risk factor for myocardial infarction and heart failure. If the lumen of the coronary vessels is significantly narrowed, even a small thrombus can block it, depriving the heart of nutrition and provoking a catastrophe. If during the intervention the endovascular surgeon sees that the vessels are damaged, it is advisable to immediately place a stent - a special device that expands the “passage” for blood.

We are the first in the world to perform such combined operations – Russian know-how. This approach can significantly improve the patient’s prognosis and do it without unnecessary difficulties for him - in one go.

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Why doesn't the hole close?

If the closure of the interatrial communication is formed during the period of intrauterine development, such babies are born with serious dysfunctions of the cardiac and respiratory systems or die even before birth. In fact, an open foramen ovale in a child’s heart is an adaptive mechanism, and not a congenital anomaly.

In 50% of people, the valve fuses with the heart wall by the end of the twelfth month of life. If they do not heal before the age of two, cardiologists classify the condition as minor anomalies of the heart (MACD).

Distinctive features of MARS:

• there is no significant hemodynamic disturbance;
• symptoms are practically absent, and if present, they are not characterized by specificity.

25–30% of the adult population lives with an open foramen ovale. For some, the valve dimensions are insufficient to completely close the hole. The primary MPP may overlap the communication, but not fuse with the interatrial wall. If the pressure in the right side of the heart increases, the valve will open and some of the venous blood will flow through the ventricle into the aorta.

Experts believe that the main cause of MARS is genetic predisposition. The presence of connective tissue dysplasia in the mother significantly increases the likelihood of their occurrence. Risk factors for having a baby with a patent foramen ovale:

• smoking of the expectant mother;
• use of certain medications by a pregnant woman;
• adverse environmental influences.

Pediatricians note that in premature infants, an open foramen ovale is observed much more often than in babies born after the 36th week of gestation. In adults, the valve covering the opening between the atria may open:

• after excessive physical exertion, for example in athletes;
• if there is a history of decompression sickness;
• in people with thrombophlebitis after episodes of pulmonary embolism.

Sometimes the defect between the atria is combined with other, more serious heart anomalies.

Gentle Intervention

For a long time, this defect was eliminated only during open heart surgery. They were carried out only when a person had serious problems. Now operations to close the “extra” hole can be performed using X-ray endovascular technologies, which are much more gentle for the patient. This allows for early treatment that prevents many serious consequences.

The opening between the atria is closed using a high-tech device that is shaped a bit like a spool of thread - wide at the ends and narrow in the middle. When folded, it is brought through the vessels to the heart using a catheter, brought to the problem area, opened using a special balloon so that the wide parts are on different sides of the hole between the atria and close it, and then fixed. The intervention process is constantly monitored using X-ray technology.

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The entire procedure is performed under local anesthesia, without general anesthesia. The rehabilitation period after such treatment takes only a few days, after which the person can return to normal activities.

Child's symptoms and behavior

In most cases, an unclosed foramen ovale in a child’s heart is not characterized by clinical manifestations. Parents may not even be aware of the existing feature. Further, in adolescence, the following are noted:

• decreased tolerance to physical activity;
• tendency to faint;
• breathing disorders.

Your doctor may suspect a patent foramen ovale in your baby if:

• pale skin;
• murmur on auscultation of the heart;
• periodically occurring cyanosis (cyanosis) of the nasolabial triangle in a child during outdoor games, screaming, coughing;
• if respiratory diseases “pursue” you much more often than other children;
• when your son or daughter is behind in growth compared to their peers;
• if the child complains of fatigue, dizziness, headaches, shortness of breath during exercise.

The discovery of varicose veins and thrombophlebitis in people under 30 years of age may also lead the doctor to think about a possible unclosed foramen ovale. A young child is not always able to accurately describe his condition, and a teenager, trying to appear older and more independent, sometimes tends to hide painful symptoms. Try not to delay visiting your doctor if there are even minor changes in your health.

Prevention

There is no special prevention for an open oval window. To prevent pathology from occurring in newborns, during pregnancy a woman should lead a healthy lifestyle, give up alcohol and smoking. She also needs to avoid contact with:

• chemicals (paints, varnish vapors, some medications);
• ionizing radiation (thermonuclear reactions, X-ray machine);
• patients with infectious diseases (if infected with rubella in the first trimester, the risk of heart disease in a child increases significantly).

This article is posted for educational purposes only and does not constitute scientific material or professional medical advice.

Diagnosis criteria

The International Classification of Diseases, 10th revision, recommends that atrial septal defect and patent foramen ovale be coded in a card using one code - Q 21.1. But in practice, doctors separate these two conditions (table below).

Ultrasound data

Cardiologists call echocardiography the “gold standard” for determining congenital heart anomalies. An ultrasound doctor judges the presence of an open foramen ovale using the following criteria:

• two-dimensional echocardiography: interruption of the signal from the septum at the location of the fossa ovale, gradual wedge-shaped thinning towards the edges of the defect, absence of volume overload of the right half of the heart, paradoxical movements of the barrier between the atria;
• Doppler echocardiography: turbulent blood flows at the location of the oval window, blood flow indicators in the right ventricle and pulmonary artery are normal.

Transesophageal echocardiographic examination is considered the most informative. But this type of diagnosis is only possible for adults or adolescents.

Additional examination methods

To determine patient management tactics, it is important to know how a hole in the interatrial septum affects heart function. Doctors do electrocardiography at rest and after exercise. This will help eliminate arrhythmia and conduction disturbances.

For adults, x-rays of the chest cavity are recommended, which will make it possible to judge the degree of hypertrophy of the right atrium and reveal congestion in the lungs.

Children with minor anomalies of heart development need consultation with a pulmonologist and immunologist. The presence of chronic foci of infections can aggravate the child’s condition, so you need to go to the otolaryngologist’s office or visit a dentist.

False chords

In our heart there are so-called “true chords”, consisting of dense muscles. They are located in both ventricles of the heart and are attached by their endings to two valves - the triscupidal and mitral. Their function is to keep the valve leaflets in their natural position and prevent them from turning into the cavity of the heart when the ventricles contract.

The false chords of the left ventricle include anatomical formations that are not attached to the valve leaflets and are located in the cavity of the heart chamber. Pathological chords can be longitudinal and transverse, and when the heart contracts, they produce heart murmurs, sometimes reminiscent of the sound of a violin.

There are additional chords that do not cause serious pathological changes. False chords can be identified using echocardiography and ultrasound. Sometimes the child has no pronounced symptoms, except for the characteristic noise when listening to the heart, but if there are too many false chords and they are located transversely, this can lead to arrhythmias and serious circulatory disorders.

MARS are not classified as heart defects, but sometimes they can pose a real danger to the health and life of a child. That is why timely detection of such pathologies is very important for the work of a cardiologist, as well as any specialist involved in ultrasound and functional diagnostics.

Possible complications

Most parents and pediatricians rightly believe that the presence of an open oval window does not threaten the child’s health. This opinion is supported by the statement of a popular pediatrician, Evgeniy Olegovich Komarovsky: this condition is not a malformation of the heart. Indeed, with a small hole, a person can play sports, work and study, and young men are even subject to conscription for military service.

But under certain conditions, a patent foramen ovale can cause the following unfavorable conditions in adults:

1. Paradoxical venous embolism is the entry of a microthromb, a bubble of fat or air from the venous system into the left atrium, and then its penetration into the systemic circulation. This condition can provoke a transient ischemic attack or stroke.
2. Migraine with a patent foramen ovale often occurs with an aura. It usually occurs in older women when blood is shunted from right to left.
3. Platypnea-orthodeoxia is a syndrome characterized by shortness of breath that occurs when standing and subsides when lying down. It is usually observed when a patent foramen ovale is combined with deformation of the IV.
4. Obstructive sleep apnea syndrome.

Some people with a patent foramen ovale develop transient global amnesia after a migraine or ischemic attack - a syndrome of memory impairment and inability to perceive new information.

Complications and prognosis

The most serious and only complication is paradoxical embolism. In this case, a blood clot (usually with thrombosis of the deep, superficial veins of the lower extremities, pelvis) or air bubbles (during diving, less often during fractures) from the venous system enter the arteries of the systemic circulation through the open oval window. Thus, ischemic stroke, myocardial infarction, intestinal ischemia, infarction of the spleen and other organs develop.

There are no clear statistics in Russia. According to studies in France and the USA, ischemic strokes account for up to 30% of cryptogenic (unexplained) strokes. Of these, about a little less than half of the cases are associated with an open foramen ovale detected in patients.

Forecast

The prognosis depends on the size of the open oval window. It is favorable for sizes up to 4 mm, low blood discharge and no increase in it over time.

In the case of the development of large blood shunts, which increase the blood supply to the right chambers of the heart and increase the degree of pulmonary hypertension, the prognosis sharply worsens.

Usually, before the development of severe pulmonary hypertension, the patient has time to undergo surgery - to close the functioning oval window with an occluder. The operation dramatically improves the prognosis for the patient.

Treatment

Holes with a diameter of 4 - 5 mm have a high chance of closing on their own. Approaches to the treatment of an open foramen ovale are individual and depend not only on the size of the defect, but also on the presence of increased pressure in the pulmonary trunk, the degree of myocardial hyperplasia, and the risk of complications.

For children with no clinical manifestations and stable defect sizes, drug therapy is not indicated.

If your child is diagnosed with a patent foramen ovale, he or she needs periodic examinations by a cardiologist.

What can happen to the oval window during life:

• closure;
• maintaining constant dimensions;
• expansion of the defect as they grow older.

Some parents give their children vitamin complexes and dietary supplements and resort to herbal treatment, but the effectiveness of such therapy has not been proven.

Indications for surgical correction of communication between the atria:

• signs of overload of the right atrium and ventricle;
• the occurrence of heart failure;
• presence of complications.

Transcatheter closure of the hole in the interatrial septum is performed. An occluder is passed to the human heart through large vessels using a catheter (see photo below), which plays the role of a patch. The manipulation is performed under X-ray and ultrasound control.

For preventive purposes, the operation is not indicated even for people of certain professions, although the available data from the medical literature confirm that performing transcatheter occlusion can help prevent decompression sickness in divers.

It is worth mentioning the possible adverse consequences of the intervention:

• embolization with occluder;
• infectious complications;
• erosion of the aorta or pericardium;
• atrial fibrillation;
• occluder thrombosis;
• the emergence of a new MPP defect.

Late complications of the transcatheter procedure include the occurrence of a residual shunt (residual discharge of blood into the left atrium) and the formation of a blood clot on the occluder. You should carefully discuss with your doctor all the pros and cons of surgical correction of the defect. Closing the oval window significantly improved the condition of patients with migraine, platypnea-orthodeoxia syndrome, and helped prevent recurrent ischemic strokes in adults. At the same time, pediatric cardiologists do not recommend surgical elimination of the IV defect in infants, considering the optimal age for radical correction to be from 2 to 5 years.

Antenatal diagnosis of premature closure of the oval window

SonoAce Ultrasound Magazine

Contains current clinical information on ultrasonography and is aimed at ultrasound doctors, published since 1996.

Introduction

In the antenatal period, venous blood normally enters the heart through the oval window, passing from the right atrium to the left, providing blood circulation to the left parts of the heart together with the ductus arteriosus. With the onset of breathing and a decrease in pulmonary vascular pressure and resistance, the magnitude of left atrial pressure increases and the pressure gradient between the atria decreases. These changes lead to the fact that the valve flap of the foramen (crista dividens) approaches the edge of the interatrial septum and closes the oval window. Functional closure takes place within a few hours. At the slightest stress (crying, feeding), which increases pressure in the right side of the heart, the oval window begins to function. Clinically, according to A. Nadas and D. Fyler [1], in 50% of children under 1 year of age, the oval window continues to function. Anatomical closure occurs by 1-2 years of life. At older ages, under conditions that increase right atrial pressure, the opening of the oval window is possible, in particular during pregnancy, severe pulmonary insufficiency and pulmonary embolism.

Intrauterine premature closure of the oval window is a rare pathology. There are a few publications that describe isolated cases of this pathology. With antenatal closure of the foramen ovale, right ventricular heart failure develops, and the child is usually born dead or dies soon after birth [2]. Diagnosis is based on an intact interatrial septum and absence of communication between the atria. The pathology is very rare and, unfortunately, leads to 100% death of newborns.

results

The subject of this article is 4 observations of antenatal premature closure of the oval window, amounting to 0.04% of the total number of detected cardiac pathologies. The pathology was determined at 30-37 weeks of gestation. In 3 observations, the pregnancy ended with timely labor and the birth of children with normal weight and height indicators, on the Apgar scale - 4-5 points, in 1 - the pregnancy was terminated. Three newborns died in the first hours of life.

First observation.

In a 19-year-old patient, at the 22nd week of pregnancy, an ultrasound examination in the cavity of the left ventricle of the fetus revealed a dense echo-positive light formation against a background of dark blood, synchronously moving with the myocardium of the posterior wall of the left ventricle throughout the cardiac cycle. The use of color flow mapping showed the absence of color flow or a persistent filling defect (according to angiographic terminology) with smooth contours, surrounded by flow. A diagnosis was made: left ventricular rhabdomyoma. In Fig. 1, a dense echo-positive formation measuring 2.7 x 2 cm is visualized, localized and completely occupying the cavity of the left ventricle. The tumor is represented by a layered, mobile formation. The patient's refusal to terminate the pregnancy allowed observation of the natural growth of the tumor.

Rice. 1.

Four-chamber cross-section of the fetal heart at 30 weeks of gestation. A cardiac tumor invades the myocardium of the posterior wall of the left ventricle and the interventricular septum. The interatrial septum is compacted, the oval window does not function (arrow). LA - left atrium, RA - right atrium, VS - interventricular septum.

At 29 weeks of pregnancy, significant growth of the tumor was noted; the extent of the process affected the walls of the aorta, the cusps of the mitral valve and the interatrial septum. By the time of birth, the tumor had caused the formation of aortic and mitral stenoses and had grown into the interatrial septum, causing premature closure of the oval window (Fig. 2).

Rice. 2.

B and M scans at the level of the interatrial septum, demonstrating the absence of communication between the atria. LA - left atrium, RA - right atrium.

The severity of hemodynamic disturbances, due to the prevalence of the tumor process, led to death 8 hours after birth. Histological diagnosis of rhabdomyoma.

Second observation.

Pregnancy 37 weeks. The fetus has pronounced effusion in the pericardium and pleural cavity. A rhythm disturbance (paroxysmal tachycardia) was noted. Anatomically, the heart is formed correctly. Echocardiography reveals dilatation of the inferior and superior vena cava (Fig. 3) due to impaired venous return of blood.

Rice. 3.

Dilatation of the inferior (IVC) and superior (SVC) vena cava during antenatal closure of the oval window.

The interatrial septum is significantly thickened, most pronounced in the area of ​​the oval window (Fig. 4), the valve of which is closed (Fig. 5). There is no blood flow through the interatrial septum.

Rice. 4.

Four-chamber cross-section of the heart. Enlargement of the atria. The interatrial septum is compacted, the oval window is closed. The presence of effusion in the abdominal cavity was noted. LA - left atrium, RA - right atrium (the arrow indicates the area of ​​the oval window, which is dense in structure).

Rice. 5.

Cross-sectional scan of the aortic root. AO - aorta, LA - left atrium, RA - right atrium, AS - interatrial septum.

From the anamnesis it was possible to find out that the pregnant woman suffers from a herpetic infection, an aggravation of the process was observed during pregnancy. In all likelihood, the infectious process caused the premature closure of the oval window.

Third observation.

Pregnancy 31 weeks. Against the background of a normally formed heart, a significant enlargement of the right atrium and signs of tricuspid insufficiency associated with the expansion of the valve ring were noted. There are signs of heart failure: hepatomegaly, effusion in the pericardial and abdominal cavities, paroxysmal tachycardia is recorded. The oval window does not function. The pregnancy is terminated.

Fourth observation.

Pregnancy 34 weeks. An ultrasound examination diagnosed the fetus as a fibroelastic form of cardiomyopathy. The left ventricle is presented in a spherical configuration with a dense luminous endocardium (Fig. 6).

Rice. 6.

Four-chamber section of the fetal heart. Fibroelastic form of cardiomyopathy. The cavity of the left ventricle (LV) is enlarged and has a rounded shape, the walls are compacted. The oval window does not function (arrow), RV is the right ventricle.

There are signs of heart failure: hepatomegaly and pericardial effusion. The fibroelastic process spread to the interatrial septum, causing premature closure of the oval window.

Discussion

During intrauterine life, premature closure of the oval window occurs due to adherence of the valve to the interatrial septum [3]. The pathology is rare—4 cases have been diagnosed in the department over many years. Literary sources also provide descriptions of only isolated cases of pathology [4-7]. There is evidence of premature closure of the oval window due to impaired circulation through the mitral and/or aortic valves [4,5,8] in hypoplastic left heart syndrome. In such cases, blood from the left ventricle through an anomalous venous channel enters the systemic vein, such as through the left atriocardial vein, through the bronchial vein or through the myocardial sinusoids to the coronary arteries and then through the fistula into the coronary sinus and the right atrium. It can be assumed that the mechanism of premature antenatal closure of the oval window in this situation is similar to its functional closure after birth: an increase in pressure in the left atrium causes the valve of the oval window to adhere to the interatrial septum.

It is believed that the abnormal nature of the kinetics of the oval window valve on ultrasound, manifested by bending of the valve towards the left atrium, and the location of the oval window valve on M-scan across the atrium with a

and
b
peaks are harbingers of premature closure of the oval window [5]. The authors associated this pattern of oval valve movement in 16 fetuses with the presence of nonimmune effusion and paroxysmal tachycardia. In one of the observations, there was spontaneous closure of fetal communication at 23 weeks of gestation. The authors, analyzing the normal pattern of valve movement of the oval window in 81 cases, suggested the possibility of premature spontaneous closure of the oval window in the case of an altered pattern of valve movement in the presence of effusion and heart rhythm disturbances.

Not only the left sections can affect the function of the oval window. Increased contractility of the right ventricle, enlargement of the right atrium and the tricuspid valve ring can also be, according to some authors [4], the cause of premature closure of the oval window. The mechanism of premature closure of the foramen ovale in these cases is similar to the hemodynamic changes in left ventricular hypoplasia syndrome and is caused by venous stagnation and an increase in ejection resistance, which also leads to an increase in left atrial pressure.

Causes that have a pathological effect on the function of the oval window valve include heart tumors. The literature provides data on tumor growth into the interatrial septum with subsequent closure of the oval window [7,9,10].

Premature closure of the oval window can be caused by an intrauterine infection, which causes exudative pericarditis and heart rhythm disturbances, as was the case in the third and second observations. In most publications [4-6], the authors associate premature closure of the oval window with non-immune effusion and heart rhythm disturbances, and they consider these manifestations to be primary. It is difficult to determine what is primary in this situation: effusion and rhythm disturbance or spontaneous closure of the oval window, which leads to hemodynamic disturbances. The latter version is supported by numerous observations from the department of functional diagnostics of fetuses with the presence of effusion and paroxysmal tachycardia and a functioning foramen ovale (Fig. 7). The department also observed self-healing during pregnancy, when the heart rhythm was completely restored, and effusion in the cavities was not visualized at the time of birth.

Rice. 7.

Four-chamber cross-section of the heart. Enlargement of the right atrium. The presence of effusion in the pericardium (thick arrow) and in the abdominal cavity was noted. The oval window is functioning (thin arrow). LA - left atrium, RA - right atrium.

As follows from the fourth observation, the cause of premature closure of the oval window may be fibroelastosis. A critical situation can arise in the early neonatal period with cyanotic heart defects with spontaneous closure of the oval window [11]. In such situations, emergency surgery is performed.

Thus, summing up our own results and literature data, we can note the following pathological conditions in the fetus, which can cause premature closure of the oval window: hypoplastic left heart syndrome, dilatation of the right heart and dilation of the tricuspid valve ring, fibroelastosis, active phase of infectious process during pregnancy, heart tumors.

Literature

1. Nadas AS, Fyler DC Pediatric Cardioilogy. — Philadelphia, 1972
2. Naeye RL, Blanc WA Prenatal narrowing or closure of the foramen ovale // Ciculation, 1964. — V.30, p.736.
3. Buncle G. Congenital heart and vascular defects. - M.: Medicine, 1980
4. Zimmer LP, Dillenburg RF, Dornelles AP, Andrade A., Zielinsky P. Prenatal restriction of the foramen ovale.// Rev Esp Cardiol, 1997, Mar;50(3):18791
5. Jouk PS, Rossignol AM, Denis B., Bost M. Restrictive ostium secundum: a new fetal malformation syndrome // Arch. Mal. Coeur Vaiss, 1987. V.80. -N4. - P. 538542.
6. Chobot V., Hornberger LK, Hagen-Ansert S., Sahn DJPrenatal detection of restrictive foramen ovale // Echocardiography, 1998, Jul;15(5):459466.
7. Gutierrez-Larraya Aguado F., Galindo Izquierdo A., Olaizola Llodio JI, Sotelo, Rodriguez MT, Merino Batres G., Velasco Bayon JM, Perez Martinez A., de Castro, Fernandez J., Ordonez Perez D., de la Fuente Perez P. Fetal cardiac tumors // J Am Soc Echocardiogr, 1990, JanFeb;3(1):1519.
8. Fraser WD, Nimrod C., Nicholson S., Harder J. Antenatal diagnosis of restriction of the foramen ovale // J. Ultrasound Med., 1989. V.8, N5, p.281283.
9. Zatikyan E.P. Cardiology of the fetus and newborn. -M.: Info-Media, 1996. — 183 p.
10. Zatikyan E.P. Heart tumors in the fetus - the possibilities of dynamic ultrasound observation in predicting the viability of a newborn // Ultrasound diagnostics. -2 000. — N2. — Page 6268.
11. Seliem MA, Shahab RA, Palileo M. Spontaneous Obstruction of Interatrial Communication in Infants with Atrioventricular Valve Atresia or Stenosis in the Neonat Period: Serial Echocar diographicDoppler Study// J. Ultrasound Med., 1989, May;8(5):2813.

SonoAce Ultrasound Magazine

Contains current clinical information on ultrasonography and is aimed at ultrasound doctors, published since 1996.

Patent foramen ovale in an adult

There is a high likelihood of ischemic stroke in young women with a patent foramen ovale who suffer from migraines.

In adults, after examination and ultrasound, cardiologists note the following risk factors for complications:

• dimensions of the oval window – more than 4 mm;
• tension of the interatrial septum during the Valsava maneuver;
• shunting even a small amount of blood to the left;

Sometimes doctors prescribe anticoagulants and antiplatelet agents to prevent the development of stroke and other thromboembolic complications.

Degrees

Patent foramen ovale is classified in different ways. Some sources divide it by hole size:

• small - less than 2 mm;
• average - from 2 to 4 mm;
• large - more than 4 mm (up to 18 mm).

Other authors believe: everything that is in the middle part of the septum is less than 5 mm in size and has periodic discharge from the right atrium to the left or vice versa is recognized as a patent foramen ovale. Anything larger than 5 mm with constant bleeding is a heart defect, atrial septal defect. The latter option manifests itself with more severe symptoms and requires treatment.