Endocardial cushion defect

The defect of the endocardial cushion is a congenital heart defect in which the normal formation of structures separating the right and left parts of the heart by the interatrial and interventricular septa is disrupted. It is not just a "hole" in the heart, but a complex developmental anomaly affecting several key elements: the atrioventricular valves (mitral and tricuspid), the septa, and the walls of the ventricles. As a result, a mixed blood shunt occurs — part of the blood from the left atrium enters the right, and from the left ventricle — into the right, leading to overload of the pulmonary circulation, hypertension in the pulmonary artery, and ultimately heart failure. In newborns, this defect may manifest within the first days of life: shortness of breath, cyanosis, poor weight gain, rapid heartbeat. However, symptoms may also appear later — in early childhood or even in adulthood, especially if the defect is partial and functional disturbances are compensated by the body.

Classification of the disease according to ICD

(0–1 month):** A complete defect manifests acutely: shortness of breath, cyanosis, refusal to breastfeed, tachycardia >160 beats/min. Without surgery, survival up to 6 months is less than 30%. A partial defect at this age is often asymptomatic or masked as "weakness." Infants (1–12 months):** This is a "critical period" for the endocardial cushion defect. By 3–4 months, pulmonary hypertension develops, growth slows down, and hepatomegaly appears. In children with partial endocardial cushion defect — moderate shortness of breath during feeding, but weight is gained, albeit slower than normal.
Preschool age (1–5 years):** If surgery is not performed, the child develops a "cardiac hump," constant fatigue, and limited physical activity. Some experience recurrent bronchitis due to congestion in the lungs.

• defect of the interatrial septum in the area of the oval window;
• defect of the interventricular septum in the area of the membranous septum;
• common atrioventricular valve instead of separate mitral and tricuspid valves.

This combination makes AVSD one of the most severe congenital heart defects in newborns. Code Q21.2 is used for both diagnosis and health statistics, but when completing medical documentation, it is mandatory to specify the form of the defect — partial or complete — in the conclusion text.

History of the disease and interesting historical facts

The first description of the endocardial cushion defect belongs to the French anatomist Jean Senac back in 1749. He noted the anomaly of the valves and septa in a child with severe heart failure but did not give it a systematic name. Only in the 1930s did the German pathologist Hans Bergman first distinguish this anomaly as an independent group, calling it "endocardial cushion defect" — by analogy with the embryonic structure from which these parts of the heart are formed.
There is an interesting fact: until the 1950s, it was believed that such a defect was incompatible with life beyond the first months. However, with the advent of cardiac surgery and the introduction of correction methods in the 1960s, the situation changed dramatically. The first successful operation to correct a partial defect was performed in 1962 by American surgeon Alfred Bailey. And in 1968 — a complete correction of AVSD in a 2-year-old child. This became a turning point: today, survival after surgery reaches 95% with timely intervention.
It is particularly noteworthy that the endocardial cushion defect has long been associated with Down syndrome — this defect occurs in almost 40% of children with trisomy 21. This allowed doctors to use it as one of the markers in screening for chromosomal anomalies even before birth.

Epidemiology (statistics of disease occurrence)

The endocardial cushion defect occurs in approximately 2–3 cases per 10,000 live births.At the same time, the partial form predominates — about 60–65% of all cases, complete — 35–40%. Interestingly, in a population with a high proportion of people with Down syndrome, the frequency of AVSD rises to 15–20% among all congenital heart defects in such children.
According to the National Registry of Congenital Heart Defects (Russia, 2020–2024), the endocardial cushion defect accounts for about 4.71% of all congenital heart anomalies in newborns. In regions with developed prenatal diagnostics, the detection rate increases: up to 80% of cases are identified before birth via ultrasound at 18–22 weeks; statistics show that:

• boys and girls are affected approximately equally (ratio 1:1);
• in 10–15% of cases, the defect is associated with other anomalies — for example, coarctation of the aorta or Ebstein's anomaly;
• in 5% of cases, there is a family history — a repeated birth of a child with the same defect in parents without chromosomal anomalies.

Important: accurate statistics depend on the availability of prenatal ultrasound and the quality of neonatal screening. In countries with low levels of medical care, the defect often remains undetected until severe decompensation occurs.

Genetic predisposition to the disease (involved genes and mutations)

The genetic basis of the endocardial cushion defect is multifaceted. The most studied association is with trisomy 21 (Down syndrome). In such patients, the risk of congenital heart defects increases by 2000 times compared to the general population. This is related to the disruption of gene expression on chromosome 21, in particular COL6A1, DSCAM and ETS2, which are involved in the formation of the endocardial cushion during the embryogenesis stage (weeks 4–7 of pregnancy).
But there are also other genetic reasons:

• CRELD1 — mutations of this gene are associated with isolated endocardial cushion defect without chromosomal abnormalities. CRELD1 encodes a protein that regulates cell adhesion in the endocardial cushion;
• TFAP2B — mutations lead to impaired differentiation of valve structures and may be associated with defects of the interventricular septum;
• GATA4 and NKX2-5 — transcription factors that are critically important for the formation of the atrioventricular connection. Their mutations are rare but cause severe forms of endocardial cushion defect.

If a child is found to have an endocardial cushion defect without signs of Down syndrome, genetic testing is recommended: FISH or massive parallel sequencing (MPS) on a panel of genes associated with congenital heart defects. This is especially important in the presence of a family history — as in 2–3% cases the defect is inherited in an autosomal dominant manner.

Risk factors for the occurrence of this disease (physical and chemical risk factors, other possible associations with this disease)

Although most cases of endocardial cushion defect have a genetic nature, there are also external factors that increase the risk of its formation. They act during the organogenesis period — from the 3rd to the 8th week of pregnancy, when the structures of the heart are laid down.
Physical factors include:

• Ionizing radiation — X-ray examination of the mother in the first trimester (especially at a dose >100 mGy) increases the risk by 1.5–2 times
• High body temperature — fever above 38.5°C in the first 6 weeks of pregnancy is associated with an increased frequency of congenital heart defects, including CHD.

Chemical factors:

• Lithium — a drug used for bipolar disorder increases the risk of CHD by 5–7 times when taken in the first trimester;

Alcohol — regular consumption of more than 30 g of pure ethanol per day in early pregnancy increases the likelihood of CHD by 30%;

• Retinoids
  

It is also worth noting:

• maternal diabetes (especially uncontrolled) — the risk is 3–4 times higher;
• epilepsy in the mother + taking valproate — the risk of CHD increases 6 times;
• infections in the first trimester (rubella, cytomegalovirus) — an indirect link through inflammatory reactions in embryonic tissue.

If you are faced with the task of prevention — the main advice: start preparing for pregnancy at least 3 months in advance. Give up alcohol, check your blood glucose level, consult a geneticist if there is a family history.

Diagnosis of this disease (Main symptoms, Laboratory Radiological examinations, Other types of disease diagnosis, Differential diagnosis)

Diagnosis begins even before birth. During the ultrasound at 18–22 weeks, the doctor pays attention to:

• enlarged sizes of the right heart chambers;
• unusual shape of the atrioventricular connection — "cross-shaped" appearance on a four-chamber view;
• absence of a clear boundary between the mitral and tricuspid valves;
• wide defect of the interatrial septum in the area of the oval window.

After birth, the clinical picture depends on the form of the defect:

• Partial defect: moderate shortness of breath during feeding, growth retardation, heart murmur (systolic, localized in 3–4 MCB on the left), blood oxygen saturation (SpO₂ 92–95% at rest).
• Complete defect: severe heart failure in the first 2–3 weeks of life — tachypnea (>60 per minute), sweating during feeding, cyanosis, hepatomegaly, arterial hypotension.

Mandatory diagnostic methods:

Differential diagnosis includes:

• Acute interatrial septal defect (for example, in atrial septal defect type ostium secundum) — here the valves are normal
• Atrioventricular canal with additional anomalies (for example, with coarctation of the aorta) — requires extended examination;
• Transposition of the great arteries with ventricular septal defect — differs in vessel positioning on ultrasound.

If you see a heart murmur in a child + growth delay — do not postpone echocardiography. The earlier the diagnosis is made, the higher the chances for successful correction.

Treatment (general treatment, pharmacological treatment, surgical treatment, other types of treatment for this type of disease)

Treatment of endocardial cushion defect is a complex process, where the main goal is not to "cure," but to restore the anatomical integrity of the heart and ensure normal hemodynamics. Pharmacotherapy here is only auxiliary and aimed at stabilizing the condition before surgery.
General treatment:
— Feeding in small portions, but more frequently (up to 8–10 times a day) to avoid fatigue;
— Weight control — daily weighings at the same time;
— Limitation of physical activity in older children
— Infection prevention — vaccination according to schedule, avoiding contacts during ARVI.
Pharmacological treatment:
The goal is to reduce the load on the heart and prevent the progression of heart failure:

• Digoxin — improves myocardial contractility, prescribed for tachycardia and reduced ejection fraction (usually 0.01–0.02 mg/kg/day in 2 doses);
• Furosemide** — diuretic, reduces blood volume, dose 1–2 mg/kg/day;
• ACE inhibitors (e.g., captopril)** — reduce afterload, dose 0.3–0.5 mg/kg/day in 2–3 doses;
• Oxygen therapy — for SpO₂ <90% at rest, but only temporarily, to avoid provoking the development of pulmonary hypertension.

Surgical treatment — the only radical method.
The operation is performed depending on the form:

• Partial defect: correction at the age of 1–2 years. Technique — closure of the interatrial septal defect with a patch (made of pericardium or synthetic material) + plastic surgery on the mitral valve (strengthening of the leaflets, reduction of the sail leaflet).
• Complete defect: surgery at 3–6 months, in case of severe decompensation — at 1–2 months. Stages:
  1. Closure of the interventricular septum with a patch;
  2. Formation of two separate atrioventricular valves from a common one (separation of the anterior leaflet into mitral and tricuspid parts);
  3. Closure of the interatrial septal defect;
  4. Strengthening of the valve rings.

Today, the method of "bivalve reconstruction" is used — it preserves the valve's own tissue, which reduces the risk of thromboembolism and the need for anticoagulants later. In rare cases (in very severe valve dysfunction), prosthetics are used, but this is a last resort.

List of drugs used to treat this disease

Below is the current list of medications used in clinical practice for endocardial cushion defect. All prescriptions must be agreed upon with a cardiologist and cardiac surgeon.

–0.5 mg/kg/day in 2–3 doses

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Important: anticoagulants (arin, rivaroxaban) are used only for valve prosthetics. They are not needed for reconstructive valve surgery — this is a big plus for the patient's quality of life.

Monitoring of the disease (control stages, prognosis, complications)

After surgery, monitoring continues for life — but the intensity decreases over time. Here are the key stages:
The first month after surgery:
— Daily examination, ECG, echocardiography on days 3–5 and 10–14;
— BNP level control (biomarker of heart failure);
— Ultrasound of the kidneys and liver — to assess organ perfusion.
The first year:
— Echocardiography every 3 months;
— ECG once every 6 months;
— Oa — once every 2–3 months.
From 1 year and older:
— EchoCG once a year;
— ECG once a year;
— In the absence of complaints — examination once every 1–2 years.
The prognosis is favorable with timely surgery:

• Survival after PDE correction — 92–95% over 10 years;
• In 85% patients, heart function remains normal without medications;
• The risk of reoperation — 5–7% (more often due to insufficiency of the reconstructed mitral valve).

Complications that may arise:

• Pulmonary hypertension — if the surgery is performed too late (after 2 years), it may become irreversible;
• Mitral valve insufficiency — the most common complication after reconstruction (10–15% cases); Arrhythmias — nodal tachycardia, atrial fibrillation (especially in adults after CHD);
• Infective endocarditis — the risk is increased in the first 6 months after surgery and with valve anomalies.

If you are a parent of a child with this diagnosis: do not be afraid of the surgery. Modern methods allow for almost normal life. The main thing is not to delay the visit to a specialist.

Age-related features of the disease (how it progresses in different age groups)</h2фект эндокардиальной подушки проявляется по-разному в зависимости от возраста — это связано с физиологическими изменениями в сосудистом русле и адаптационными возможностями организма.
N (0–1 month):**
The complete defect manifests acutely: shortness of breath, cyanosis, refusal to breastfeed, tachycardia >160 beats/min. Without surgery, survival up to 6 months is less than 30%. A partial defect at this age is often asymptomatic or masked as "weakness."
Infants (1–12 months):**
This is a "critical period" for PDA. By 3–4 months, pulmonary hypertension develops, growth slows down, and hepatomegaly appears. In children with CHD, there is moderate shortness of breath during feeding, but weight is gained, albeit slower than normal.
Preschool age (1–5 years):**
If surgery is not performed, a "cardiac hump" forms, constant fatigue, and limited physical activity. Some experience recurrent bronchitis due to congestion in the lungs.
School and adolescent age (6–18 years):**
In untreated CHD, there is a gradual development of pulmonary hypertension, arrhythmias, and decreased exercise tolerance. In adults with untreated PDA, there is a high risk of heart failure and sudden death by the age of 20–30 years.
Adults (18+ years):**
There are rare cases where the defect remained unnoticed until adulthood. More often, it is a partial form with minimal symptoms. But even with good health, such patients are at increased risk:

• myocardial infarction (due to left ventricular hypertrophy);
• thromboembolism (especially in atrial fibrillation);
• pregnancy — high risk of decompensation, so a consultation with a cardiologist is needed before conception.

Important even after a successful childhood surgery, adult patients require lifelong monitoring. The heart is not "healed," but "restructured," and its reserves are limited.

Questions and Answers

Question 1: Can the endocardial cushion defect be treated without surgery?**
No. No medication, diet, or physiotherapy will eliminate the anatomical anomaly. Pharmacotherapy helps stabilize the condition but does not solve the problem. Only surgical correction can restore normal hemodynamics. There are experimental catheter occlusion methods for ECD, but they are not yet standardized and are only used in clinical trials.
Question 2: What is the likelihood of having a second child with the same defect?**
If the first child has an endocardial cushion defect without chromosomal anomalies and without a detected mutation in the CRELD1/GATA4 genes — the recurrence risk is 2–3%. If the child has Down syndrome — the risk for the next child with ECD is no higher than the population risk (2–3 in 10,000), but the overall risk of congenital heart defects increases to 10%. A consultation with a geneticist is mandatory before planning the next pregnancy.
Question 3: Can a child with a repaired defect participate in sports?**
Yes, but with reservations. After successful correction in childhood, most children lead an active lifestyle. Swimming, athletics, and cycling are allowed. Contact sports (football, hockey) and extreme loads (weightlifting, skydiving) are contraindicated. Before starting activities — a mandatory conclusion from a cardiologist with an EchoCG and a stress test.
Question 4: Why do children with Down syndrome more often have this defect?**
Because chromosome 21 contains genes that regulate the migration and differentiation of cells in the endocardial cushion during the 4th to 7th week of embryogenesis. An excess of copies of these genes disrupts the balance of signaling pathways (Wnt, Notch, BMP), leading to incomplete separation of the atrioventricular canal. This is not a "coincidence," but a consequence of the genetic program.
Question 5: What to do if the defect is discovered only at 15 years old?**
Do not panic. First, conduct a complete examination: EchoCG, CT/MRI of the heart, catheterization (if there are signs of pulmonary hypertension), genetic analysis. Then — a joint decision by the cardiologist, cardiac surgeon, and patient. Surgery in adolescence is technically more complex, but possible. In some cases, valve reconstruction without septal replacement is sufficient. The main thing is not to wait until irreversible pulmonary hypertension develops.

1. "Let's wait until the child grows up."
Mistake: delaying surgery for PDA leads to irreversible pulmonary hypertension. By the age of 2, the chances of successful correction decrease by 20–30%.
How to avoid: If the diagnosis is made before 3 months, surgery should be planned before 6 months.
2. To think that "a heart murmur is normal in children"**
Mistake: not all murmurs are harmless. The murmur in PDA is systolic, localized in the 3rd-4th left intercostal space, and increases with physical exertion.
How to avoid: In case of any murmur — echocardiography within 1 week.
3. Prescribing antibiotics "just in case" for ARVI**
Mistake: prophylaxis of endocarditis with antibiotics is not required for reconstructed valves without prostheses. The excessive use of antibiotics leads to dysbiosis and resistance.
How to avoid: Antibiotic prophylaxis only for invasive procedures (tooth extraction, cystoscopy) and only on the recommendation of a cardiologist.
4. Ignoring genetic counseling after the birth of a child with PDEP**
Mistake: you may miss the opportunity to identify a hereditary form, which affects planning the next pregnancy.
How to avoid: Genetic testing — within 1 month after diagnosis.

Conclusion

The defect of the endocardial cushion is not a sentence, but a task that modern cardiac surgery solves with high efficiency. The key to success is early diagnosis, a clear understanding of the form of the defect, and timely surgical intervention. The partial form can be corrected at 1–2 years, the complete form at 3–6 months. After surgery, most children lead a full life: they study, engage in sports, and give birth to healthy children.
The main thing to remember:

• Do not ignore heart murmurs in a child — this may be the first signal;
• Prenatal ultrasound at 18–22 weeks — your best ally;
• Genetic counseling is not a luxury, but a necessity;
• Surgery is not the end of the road, but the beginning of a new life.

If you are faced with this diagnosis — you are not alone. In Russia, there are more than 20 high-qualification centers that correct hundreds of such cases annually. Trust the specialists, ask questions, and remember: the heart can be complex, but it is capable of amazing things — especially when handled by professionals.