What is an open oval window, when and how is it dangerous

What is this defect, and what is its physiology

An open oval window in the heart of a newborn is a variant of the norm. What is it for? The fetal circulation 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 dividing the atria - the primary interatrial septum (MPP) 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 primary septum.
3. By the end of the seventh week, the primary MPP develops into a valve covering the oval window.

The fetus does not breathe, and its "gas exchange point" is the placenta, therefore, the body does not need a small circle of blood circulation. Instead, it has:

• ductus arteriosus - a vessel connecting the aorta with the pulmonary artery;
• oval window - the opening between the ventricles.

The unborn child 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 goes there. This mixed blood (arterial - of the mother and venous - of the fetus) flows into the right half of the heart.

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

How the pulmonary circulation turns on

With the first cry, when the oxygenated arterial blood of the mother stops flowing, the concentration of carbon dioxide in the newborn increases. Vascular receptors "signal" 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 streams of arterial (from the lungs) and venous (from internal organs) blood no longer intersect.

Two circles of blood circulation begin to function. Subsequently, the secondary septum is soldered to the heart wall. In most people, an oval fossa forms in the place of the oval window.

Why does not the hole close

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

In 50% of people, the valve with the heart wall grows together by the end of the twelfth month of life. If they do not get drunk until the age of two, cardiologists attribute the condition to minor anomalies of heart development (MARS).

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 oval window. For some, the valve size is not large enough to completely close the hole. The primary MPP may overlap the message, but not fuse with the interatrial wall. If the pressure in the right side of the heart rises, the valve opens and some of the venous blood flows through the ventricle into the aorta.

Experts believe that the main reason for 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 an open oval window:

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

Pediatricians note that in premature infants, an open oval window 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;
• with a history of decompression sickness;
• in people with thrombophlebitis after suffering episodes of pulmonary embolism.

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

Symptoms and behavior of the child

An open oval window in the heart of a child in most cases is not characterized by clinical manifestations. Parents may not even be aware of the existing feature. Further, in adolescence, the following are noted:

• decreased exercise tolerance;
• tendency to faint;
• breathing disorders.

The doctor may suspect an open oval window in your baby when:

• pallor of the skin;
• murmur during auscultation of the heart;
• recurrent cyanosis (cyanosis) of the nasolabial triangle in a child during outdoor games, screaming, coughing;
• if respiratory diseases "haunt" you much more often than other children;
• when your son or daughter lags behind peers in height;
• if the child complains of fatigue, dizziness, headaches, shortness of breath during exercise.

The detection of varicose veins and thrombophlebitis in persons under 30 years of age can also give the doctor the idea of ​​a possible open 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 the painful symptoms. Try not to delay your doctor's appointment if there are even minor health changes.

Diagnosis criteria

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

Ultrasound data

Cardiologists call echocardiography the "gold standard" for determining congenital heart anomalies. The ultrasound diagnostics doctor judges the presence of an open foramen ovale according to the following criteria:

• two-dimensional echocardiography: a break in the signal from the septum at the site of the fossa oval, gradual wedge-shaped thinning to the edges of the defect, no overload of the right half of the heart, paradoxical movement of the obstruction 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.

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

Additional examination methods

To determine the tactics of patient management, it is important to know how the opening in the atrial septum affects the function of the heart. Doctors do electrocardiography at rest and after exercise. This will help rule out arrhythmias and conduction disturbances.

An X-ray of the chest cavity organs is recommended for adults, which will make it possible to judge the degree of hypertrophy of the right atrium, reveal congestion in the lungs.

Children with small developmental anomalies of the heart need the advice of a pulmonologist and immunologist. The presence of chronic foci of infections can aggravate the child's condition, so you need to look into the office of an otolaryngologist, visit a dentist.

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 facilitated by the statement of the popular pediatrician - Evgeny Olegovich Komarovsky: this condition is not a malformation of the heart. Indeed, with the small size of the hole, a person can play sports, work and study, and young men are even subject to conscription for military service.

But under certain conditions, an open oval window can cause the following adverse conditions in adults:

1. Paradoxical venous embolism - the entry of a microthrombus, a bubble of fat or air from the vein 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 an open oval window often proceeds with an aura. It usually occurs in older women with a right-to-left blood dump.
3. Platypnea-orthodeoxia is a syndrome characterized by shortness of breath that occurs when standing and subsides when lying down. Usually observed when an open oval hole is combined with deformation of the MPP.
4. Obstructive sleep apnea syndrome.

Some people with an open oval window after a migraine or an ischemic attack develop transient global amnesia - a syndrome of memory disorder and inability to perceive new information.

Treatment

Holes with a diameter of 4 - 5 mm have a high chance of closing on their own. Approaches to the therapy of an open oval window are individual, depending not only on the size of the defect, but also on the presence of an increase in 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 an open oval window, he needs periodic check-ups by a cardiologist.

What can happen to an oval window during life:

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

Some parents give their child vitamin complexes and dietary supplements, 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;
• the presence of complications.

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

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

Possible adverse effects of the intervention are worth mentioning:

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

Experts refer to the late complications of the transcatheter procedure as the occurrence of a residual shunt (residual discharge of blood into the left atrium) and the formation of a thrombus on the occluder. All the pros and cons of prompt elimination of the defect should be carefully discussed with the doctor. Closure of the oval window significantly improved the condition of patients with migraine, platypnea-orthodeoxia syndrome, and contributed to the prevention of recurrent ischemic strokes in adults. At the same time, pediatric cardiologists do not recommend surgical elimination of the MPP defect in infants, considering the age from 2 to 5 years to be optimal for radical correction.

An open oval window in an adult

There is a high likelihood of ischemic stroke in young women with an open oval window, suffering from migraine.

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

• the size of the oval window is more than 4 mm;
• the 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 stroke and other thromboembolic complications.