Atrioventricular septal defect is a congenital heart defect. It is a combination of atrial septal defect and ventricular septal defect.
What is an atrioventricular septal defect?
Atrioventricular septal defect is a congenital heart malformation and one of the most complex congenital heart defects. Because the combination of atrial septal defect and ventricular septal defect creates a connection (shunt), the heart defect is one of the so-called shunt vitias. Shuntvitias are congenital heart defects in which the arterial and venous legs of the circulation are connected. In atrioventricular septal defect, a double left-right shunt forms. The defect is divided into three categories according to severity:
- Complete atrioventricular septal defect.
- Partial atrioventricular septal defect
- Ostium-primum defect.
In 35 percent of cases, there are other concomitant heart defects or abnormalities of organs.
The exact cause of the malformation is unknown. Approximately 0.19 per 1000 newborns are affected annually. Girls and boys develop the disease at about the same rate. The defect occurs with striking frequency in association with Down syndrome. About 43 percent of all patients with an atrioventricular septal defect also have Down syndrome. The children are born with a large defect in the cardiac septum. There is a hole in both the atrial septum (artrial septal defect) and the ventricular septum (ventricular septal defect). The heart valve between the left atrium and left ventricle (tricuspid valve) and the valve between the left ventricle and left atrium (mitral valve) are malformed. In addition, the aortic valve is displaced forward and upward. The aortic valve is located between the left ventricle and the aorta.
Symptoms, complaints, and signs
Whether and what symptoms are seen in the newborn depends on the size and location of the defect. The amount of blood flow, the amount of pressure in the lungs, and the extent of the valve defects also affect the symptoms of the heart defect. The abnormalities do not play a role before birth because the child is supplied with oxygenated blood from the mother. After birth, oxygen is no longer absorbed by the mother, but by the child’s lungs. For this, the lungs must unfold and the pulmonary vessels dilate. In the case of a large atrioventricular defect, the high pressure that exists in the left heart forces blood through the wall defect into the right side of the heart. This medical phenomenon is called a left-to-right shunt. In the right heart, the additional blood increases the pressure. The blood flows through the pulmonary vessels at an increased pressure, putting strain on the lungs. Both chambers of the heart also have to do significantly more work. The right side of the heart suffers from the increased pressure, and the left side is affected by the increased blood flow from the lungs. The inability of the AV valve to close causes more blood to flow back into the left heart. This has to be ejected additionally with each heartbeat. Within the first few days of life, the child’s heart is put under so much strain that heart failure develops. The affected children suffer from shortness of breath and show water retention all over the body. The skin, eyelids and liver are swollen. The children become increasingly weak and refuse to drink. In some cases, a pressure reversal occurs due to a protective mechanism. In this case, oxygen-poor blood from the right heart passes through the septal defect into the left heart. Here, a blue discoloration of the lips and mouth region is seen. If the hypertension is fixed in the lungs, surgery can no longer be performed. Children with such fixed pulmonary hypertension have a maximum life expectancy of 10 to 20 years. However, artrioventricular septal defect is usually detected early.
Diagnosis and progression
As early as the first week, a heart murmur may be heard on auscultation with a stethoscope. This is caused by backflow of blood through the defective AV valve. If an atrioventricular septal defect is suspected, an electrocardiogram can be performed. This provides specific evidence of the heart defect. An x-ray will show a significantly enlarged heart. The gold standard for fully assessing the severity of the heart defect is echocardiography.If an atrioventricular septal defect is already suspected during pregnancy, a prenatal risk ultrasound can be performed. From as early as the 16th to 20th week of pregnancy, a heart defect can be diagnosed quite reliably with this procedure. However, the heart defect cannot be detected during normal routine ultrasound examinations. The examinations take place in specially trained perinatal centers.
In a fully formed atrioventricular septal defect (AVSD), all four chambers of the heart are connected from birth due to a heart malformation. This means that there is constant mixing between arterial and venous blood and the efficiency of the heart’s pumping action is greatly reduced. Complications that develop due to untreated AVSD are usually pulmonary hypertension (pulmonary hypertension), which leads to a thickening of the muscular medial wall (media) of the pulmonary arteries as a physiological counter-reaction. In a kind of vicious circle, the two effects reinforce each other (Eisenmenger reaction). The increasing insufficiency of the heart leads to a poor prognosis if left untreated. Open heart surgery can improve the long-term prognosis very well. The main steps during surgery consist of reconstruction of the two atrioventricular valves, the mitral valve in the left heart and the tricuspid valve in the right heart, and elimination of the septal defects by applying artificial patches. In addition to the classic surgical risks associated with open-heart surgery in a baby or young child, a specific risk is a disturbance of the electrical excitation system. The AV node, which collects the electrical impulses from the pacemaker (sinus node) and transmits them to the downstream systems with a slight delay, is usually particularly affected. If the problem cannot be solved with medication, an artificial pacemaker must be implanted.
When should you see a doctor?
A genetic atrioventricular septal defect (AVSD) becomes symptomatic in the newborn within the first few days. It is unnecessary to ask at what point medical attention should be sought. The severity of the cardiac malformation can be determined by echocardiography and confirmed and supplemented by ECG findings. In the case of a fully formed AVSD, all four chambers of the heart are connected and if left untreated, the prognosis for the newborn is extremely unfavorable. Surgical intervention in a specialized hospital closes the connections between the two chambers and usually also replaces the two non-functioning heart valves between the left atrium and left chamber (mitral valve) and between the right atrium and right chamber (tricuspid valve). The survival prognosis for the newborns is dramatically improved by such an operation. For those affected, a nearly normal life is usually possible after a successful operation, if the reconstructive surgery is performed early enough and no irreversible damage has yet formed in the lungs or heart muscle. After reaching adulthood, the intervals for medical check-ups may well be extended if the patient continues to be free of symptoms. However, individuals should be alert for specific symptoms that may indicate a recurrence of the problem and that should be promptly evaluated by a cardiologist or by an experienced primary care physician.
Treatment and therapy
If the heart defect is not treated, only 10 percent of affected children are alive after six months. Patients develop pulmonary hypertension and, as a result, what is known as an Eisenmenger reaction. However, most atrioventricular septal defects are detected early and are operable. Using the heart-lung machine, the arterial and venous circulation are separated again. During the first six months after surgery, endocarditis prophylaxis is given with medication in accordance with current medical guidelines. Following the operation, regular check-ups must also be performed. The long-term prognosis of the operated children is very good. Only rarely does a second operation have to be performed.
Outlook and prognosis
The prognosis of atrioventricular septal defect is not very favorable. If healing takes place, there is an increased risk of secondary disease.More than 35% of the patients develop further heart diseases, which are present for life and can no longer be cured. In the majority of patients, the underlying disease is diagnosed as Down syndrome. Approximately ¼ of atrioventricular septal defect sufferers belong to them. Essential for the prognosis are the diagnosis and the start of treatment. Children are already born with the defect and require treatment as soon as possible. Without medical care, there is a risk of premature death within the first weeks or months of life. According to statistics, untreated children die within the first 6 months of life with a probability of approximately 90%. The respiratory distress and non-functional cardiac activity puts so much stress on the organism that there is little chance of survival without intensive medical therapy. Multiple organ failure or death by suffocation would be the devastating consequences. With professional medical care, cardiac activity is stabilized with a heart-lung machine. This greatly improves the chance of survival. Once the child is in a stable state of health, a surgical procedure is performed. This significantly increases the likelihood of survival and allows the patient to have sufficient independent cardiac activity.
Because the exact causes of atrioventricular septal defect are unknown, the disease cannot be prevented. If a child in a family has already been born with the heart defect, there is a 2.5 percent risk of recurrence when another child is born. Especially in families with such an increased risk of the disease, prenatal diagnostics can help detect the heart defect early. The earlier the diagnosis is made, the better the prognosis.
In this disease, in most cases, the affected person has no or very few options and measures of aftercare. In this case, the affected person is first dependent on a comprehensive and, above all, early diagnosis in order to permanently alleviate the symptoms and to detect the heart defect at an early stage. Since this is also a congenital disease, it cannot be treated causally, but only symptomatically. A complete cure cannot occur in this case, nor can self-healing occur. In most cases, this defect is alleviated by surgical intervention. However, the further course depends very much on the time of diagnosis, so that no general prediction can be made. After such an operation, the affected person should in any case rest and take care of his body. Strenuous activities or stressful activities should be avoided in order not to put unnecessary strain on the heart. Regular checks and examinations are also necessary after the operation. If the operation is successful, there is no reduction in life expectancy for those affected. However, most of those affected also suffer from other heart complaints that also still need to be treated.
Here’s what you can do yourself
Atrioventricular septal defect, as a congenital heart disease, poses a challenge to affected families on a day-to-day basis. Especially with increased risk of disease, prenatal diagnosis is essential to detect the heart defect early. However, it is often possible for those affected to lead an almost normal life. However, it is advisable to have regular intervals for medical progress checks and to strictly adhere to medication schedules. Other important aspects are abstaining from nicotine and a healthy lifestyle. In order to avoid psychogenic stress, in case of emotional strain as well as in case of socio-legal questions, it is recommended to visit self-help groups and suitable therapists. Here, problems such as: special educational needs, sporting restrictions, school disadvantage compensation or relaxation procedures can be clarified. Mental and physical mobility promote self-confidence and have stabilizing properties. Affected persons are therefore encouraged to take an active part in public life, also on their own initiative. Practicing hobbies serves as a reasonable start and motivational aid. Well-organized trips and excursions contribute significantly to a healthy quality of life; doing without has a negative effect on the mental state.The support of family and friends as a strong social network can also increase one’s own sense of well-being and reduce tension. Further information on the subject of heart disease is also available from the Deutsche Herzstiftung e.V. and the Bundesverband Herzkranke Kinder.